(a) Interpretation: The peptide Gly − Leu − Val , is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH = 6 is to be stated. Concept introduction: Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Question

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Answer 1

Question

Chapter 27, Problem 27.10P

Interpretation Introduction

(a)

Interpretation:

The peptide Gly−Leu−Val, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide Gly−Leu−Val is neutral as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 1

There will be no charge on the peptide, Gly−Leu−Val at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide Gly−Leu−Val is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 2

Figure 1

This tripeptide contains one amino group and one carboxylic group. So, this amino acid is neutral in nature. The amine group of glycine having pKa equals to 9.60 remains in the protonated form at pH=6. On the other hand, carboxylic group of valine having pKa equals to 2.32 remains in the carboxylate form at pH=6 as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 3

Figure 2

Therefore, the net charge on the peptide, Gly−Leu−Val remains zero at pH=6.

Conclusion

The peptide Gly−Leu−Val is neutral and no net charge is present on this peptide.

Interpretation Introduction

(b)

Interpretation:

The peptide, Leu−Trp−Lys−Gly−Lys, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide, Leu−Trp−Lys−Gly−Lys is basic as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 4

The net charge on the peptide, Leu−Trp−Lys−Gly−Lys is +3 at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide, Leu−Trp−Lys−Gly−Lys is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 5

Figure 3

This given peptide contains three amino group in its chain and one carboxylic group. So, this amino acid is basic in nature. All the amine group of the given peptide having value of pKa greater than pH=6, so, the amine group remains in the protonated form. On the other hand, carboxylic group of lysine having pKa equals to 2.18 remains in the carboxylate form at pH=6 as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 6

Figure 4

Therefore, the net charge of +3 is present on the peptide, Leu−Trp−Lys−Gly−Lys at pH=6.

Conclusion

The peptide, Leu−Trp−Lys−Gly−Lys is basic in nature and +3 charge is present on this peptide.

Interpretation Introduction

(c)

Interpretation:

The peptide, N−acetyl−Asp−Val−Ser−Arg−Arg, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide N−acetyl−Asp−Val−Ser−Arg−Arg is neutral as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 7

There will be no charge on the peptide, N−acetyl−Asp−Val−Ser−Arg−Arg at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide N−acetyl−Asp−Val−Ser−Arg−Arg is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 8

Figure 5

This given peptide contains two amino groups in the side chain and two carboxylic groups. So, this amino acid is neutral in nature. All the amine groups of this peptide having pKa greater than pH=6, so, amine groups remain protonated. On the other hand, carboxylic group of arginine and aspartic acids having pKa smaller than pH=6 and remains in the carboxylate form as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 9

Figure 6

Therefore, the net charge on the peptide, N−acetyl−Asp−Val−Ser−Arg−Arg remains zero at pH=6.

Conclusion

The peptide N−acetyl−Asp−Val−Ser−Arg−Arg is neutral and no net charge is present on this peptide.

Interpretation Introduction

(d)

Interpretation:

The peptide Glu−Lys−Asp−Ala−Phe−Ile, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide Glu−Lys−Asp−Ala−Phe−Ile is acidic in nature as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 10

The charge present on the peptide, Glu−Lys−Asp−Ala−Phe−Ile is −2 at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide Glu−Lys−Asp−Ala−Phe−Ile is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 11

Figure 7

This given peptide contains two amino groups in the side chain and four carboxylic groups. So, this amino acid is acidic in nature. All the amine groups of this peptide having pKa greater than pH=6, so, amine groups remain protonated. On the other hand, carboxylic group of the peptide is having pKa value smaller than pH=6 and remains in the carboxylate form as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 12

Figure 8

Therefore, the net charge on the peptide, Glu−Lys−Asp−Ala−Phe−Ile is −2 at pH=6.

Conclusion

The peptide Glu−Lys−Asp−Ala−Phe−Ile is acidic and −2 net charge is present on this peptide.

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Answer 2

Question

Chapter 27, Problem 27.10P

Interpretation Introduction

(a)

Interpretation:

The peptide Gly−Leu−Val, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide Gly−Leu−Val is neutral as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 1

There will be no charge on the peptide, Gly−Leu−Val at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide Gly−Leu−Val is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 2

Figure 1

This tripeptide contains one amino group and one carboxylic group. So, this amino acid is neutral in nature. The amine group of glycine having pKa equals to 9.60 remains in the protonated form at pH=6. On the other hand, carboxylic group of valine having pKa equals to 2.32 remains in the carboxylate form at pH=6 as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 3

Figure 2

Therefore, the net charge on the peptide, Gly−Leu−Val remains zero at pH=6.

Conclusion

The peptide Gly−Leu−Val is neutral and no net charge is present on this peptide.

Interpretation Introduction

(b)

Interpretation:

The peptide, Leu−Trp−Lys−Gly−Lys, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide, Leu−Trp−Lys−Gly−Lys is basic as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 4

The net charge on the peptide, Leu−Trp−Lys−Gly−Lys is +3 at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide, Leu−Trp−Lys−Gly−Lys is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 5

Figure 3

This given peptide contains three amino group in its chain and one carboxylic group. So, this amino acid is basic in nature. All the amine group of the given peptide having value of pKa greater than pH=6, so, the amine group remains in the protonated form. On the other hand, carboxylic group of lysine having pKa equals to 2.18 remains in the carboxylate form at pH=6 as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 6

Figure 4

Therefore, the net charge of +3 is present on the peptide, Leu−Trp−Lys−Gly−Lys at pH=6.

Conclusion

The peptide, Leu−Trp−Lys−Gly−Lys is basic in nature and +3 charge is present on this peptide.

Interpretation Introduction

(c)

Interpretation:

The peptide, N−acetyl−Asp−Val−Ser−Arg−Arg, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide N−acetyl−Asp−Val−Ser−Arg−Arg is neutral as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 7

There will be no charge on the peptide, N−acetyl−Asp−Val−Ser−Arg−Arg at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide N−acetyl−Asp−Val−Ser−Arg−Arg is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 8

Figure 5

This given peptide contains two amino groups in the side chain and two carboxylic groups. So, this amino acid is neutral in nature. All the amine groups of this peptide having pKa greater than pH=6, so, amine groups remain protonated. On the other hand, carboxylic group of arginine and aspartic acids having pKa smaller than pH=6 and remains in the carboxylate form as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 9

Figure 6

Therefore, the net charge on the peptide, N−acetyl−Asp−Val−Ser−Arg−Arg remains zero at pH=6.

Conclusion

The peptide N−acetyl−Asp−Val−Ser−Arg−Arg is neutral and no net charge is present on this peptide.

Interpretation Introduction

(d)

Interpretation:

The peptide Glu−Lys−Asp−Ala−Phe−Ile, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide Glu−Lys−Asp−Ala−Phe−Ile is acidic in nature as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 10

The charge present on the peptide, Glu−Lys−Asp−Ala−Phe−Ile is −2 at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide Glu−Lys−Asp−Ala−Phe−Ile is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 11

Figure 7

This given peptide contains two amino groups in the side chain and four carboxylic groups. So, this amino acid is acidic in nature. All the amine groups of this peptide having pKa greater than pH=6, so, amine groups remain protonated. On the other hand, carboxylic group of the peptide is having pKa value smaller than pH=6 and remains in the carboxylate form as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 12

Figure 8

Therefore, the net charge on the peptide, Glu−Lys−Asp−Ala−Phe−Ile is −2 at pH=6.

Conclusion

The peptide Glu−Lys−Asp−Ala−Phe−Ile is acidic and −2 net charge is present on this peptide.

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Answer 3

Question

Chapter 27, Problem 27.10P

Interpretation Introduction

(a)

Interpretation:

The peptide Gly−Leu−Val, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide Gly−Leu−Val is neutral as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 1

There will be no charge on the peptide, Gly−Leu−Val at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide Gly−Leu−Val is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 2

Figure 1

This tripeptide contains one amino group and one carboxylic group. So, this amino acid is neutral in nature. The amine group of glycine having pKa equals to 9.60 remains in the protonated form at pH=6. On the other hand, carboxylic group of valine having pKa equals to 2.32 remains in the carboxylate form at pH=6 as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 3

Figure 2

Therefore, the net charge on the peptide, Gly−Leu−Val remains zero at pH=6.

Conclusion

The peptide Gly−Leu−Val is neutral and no net charge is present on this peptide.

Interpretation Introduction

(b)

Interpretation:

The peptide, Leu−Trp−Lys−Gly−Lys, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide, Leu−Trp−Lys−Gly−Lys is basic as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 4

The net charge on the peptide, Leu−Trp−Lys−Gly−Lys is +3 at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide, Leu−Trp−Lys−Gly−Lys is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 5

Figure 3

This given peptide contains three amino group in its chain and one carboxylic group. So, this amino acid is basic in nature. All the amine group of the given peptide having value of pKa greater than pH=6, so, the amine group remains in the protonated form. On the other hand, carboxylic group of lysine having pKa equals to 2.18 remains in the carboxylate form at pH=6 as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 6

Figure 4

Therefore, the net charge of +3 is present on the peptide, Leu−Trp−Lys−Gly−Lys at pH=6.

Conclusion

The peptide, Leu−Trp−Lys−Gly−Lys is basic in nature and +3 charge is present on this peptide.

Interpretation Introduction

(c)

Interpretation:

The peptide, N−acetyl−Asp−Val−Ser−Arg−Arg, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide N−acetyl−Asp−Val−Ser−Arg−Arg is neutral as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 7

There will be no charge on the peptide, N−acetyl−Asp−Val−Ser−Arg−Arg at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide N−acetyl−Asp−Val−Ser−Arg−Arg is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 8

Figure 5

This given peptide contains two amino groups in the side chain and two carboxylic groups. So, this amino acid is neutral in nature. All the amine groups of this peptide having pKa greater than pH=6, so, amine groups remain protonated. On the other hand, carboxylic group of arginine and aspartic acids having pKa smaller than pH=6 and remains in the carboxylate form as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 9

Figure 6

Therefore, the net charge on the peptide, N−acetyl−Asp−Val−Ser−Arg−Arg remains zero at pH=6.

Conclusion

The peptide N−acetyl−Asp−Val−Ser−Arg−Arg is neutral and no net charge is present on this peptide.

Interpretation Introduction

(d)

Interpretation:

The peptide Glu−Lys−Asp−Ala−Phe−Ile, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide Glu−Lys−Asp−Ala−Phe−Ile is acidic in nature as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 10

The charge present on the peptide, Glu−Lys−Asp−Ala−Phe−Ile is −2 at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide Glu−Lys−Asp−Ala−Phe−Ile is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 11

Figure 7

This given peptide contains two amino groups in the side chain and four carboxylic groups. So, this amino acid is acidic in nature. All the amine groups of this peptide having pKa greater than pH=6, so, amine groups remain protonated. On the other hand, carboxylic group of the peptide is having pKa value smaller than pH=6 and remains in the carboxylate form as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 12

Figure 8

Therefore, the net charge on the peptide, Glu−Lys−Asp−Ala−Phe−Ile is −2 at pH=6.

Conclusion

The peptide Glu−Lys−Asp−Ala−Phe−Ile is acidic and −2 net charge is present on this peptide.

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Answer 4

Question

Chapter 27, Problem 27.10P

Interpretation Introduction

(a)

Interpretation:

The peptide Gly−Leu−Val, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide Gly−Leu−Val is neutral as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 1

There will be no charge on the peptide, Gly−Leu−Val at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide Gly−Leu−Val is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 2

Figure 1

This tripeptide contains one amino group and one carboxylic group. So, this amino acid is neutral in nature. The amine group of glycine having pKa equals to 9.60 remains in the protonated form at pH=6. On the other hand, carboxylic group of valine having pKa equals to 2.32 remains in the carboxylate form at pH=6 as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 3

Figure 2

Therefore, the net charge on the peptide, Gly−Leu−Val remains zero at pH=6.

Conclusion

The peptide Gly−Leu−Val is neutral and no net charge is present on this peptide.

Interpretation Introduction

(b)

Interpretation:

The peptide, Leu−Trp−Lys−Gly−Lys, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide, Leu−Trp−Lys−Gly−Lys is basic as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 4

The net charge on the peptide, Leu−Trp−Lys−Gly−Lys is +3 at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide, Leu−Trp−Lys−Gly−Lys is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 5

Figure 3

This given peptide contains three amino group in its chain and one carboxylic group. So, this amino acid is basic in nature. All the amine group of the given peptide having value of pKa greater than pH=6, so, the amine group remains in the protonated form. On the other hand, carboxylic group of lysine having pKa equals to 2.18 remains in the carboxylate form at pH=6 as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 6

Figure 4

Therefore, the net charge of +3 is present on the peptide, Leu−Trp−Lys−Gly−Lys at pH=6.

Conclusion

The peptide, Leu−Trp−Lys−Gly−Lys is basic in nature and +3 charge is present on this peptide.

Interpretation Introduction

(c)

Interpretation:

The peptide, N−acetyl−Asp−Val−Ser−Arg−Arg, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide N−acetyl−Asp−Val−Ser−Arg−Arg is neutral as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 7

There will be no charge on the peptide, N−acetyl−Asp−Val−Ser−Arg−Arg at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide N−acetyl−Asp−Val−Ser−Arg−Arg is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 8

Figure 5

This given peptide contains two amino groups in the side chain and two carboxylic groups. So, this amino acid is neutral in nature. All the amine groups of this peptide having pKa greater than pH=6, so, amine groups remain protonated. On the other hand, carboxylic group of arginine and aspartic acids having pKa smaller than pH=6 and remains in the carboxylate form as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 9

Figure 6

Therefore, the net charge on the peptide, N−acetyl−Asp−Val−Ser−Arg−Arg remains zero at pH=6.

Conclusion

The peptide N−acetyl−Asp−Val−Ser−Arg−Arg is neutral and no net charge is present on this peptide.

Interpretation Introduction

(d)

Interpretation:

The peptide Glu−Lys−Asp−Ala−Phe−Ile, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide Glu−Lys−Asp−Ala−Phe−Ile is acidic in nature as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 10

The charge present on the peptide, Glu−Lys−Asp−Ala−Phe−Ile is −2 at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide Glu−Lys−Asp−Ala−Phe−Ile is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 11

Figure 7

This given peptide contains two amino groups in the side chain and four carboxylic groups. So, this amino acid is acidic in nature. All the amine groups of this peptide having pKa greater than pH=6, so, amine groups remain protonated. On the other hand, carboxylic group of the peptide is having pKa value smaller than pH=6 and remains in the carboxylate form as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 12

Figure 8

Therefore, the net charge on the peptide, Glu−Lys−Asp−Ala−Phe−Ile is −2 at pH=6.

Conclusion

The peptide Glu−Lys−Asp−Ala−Phe−Ile is acidic and −2 net charge is present on this peptide.

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Answer 5

Chapter 27, Problem 27.10P

Interpretation Introduction

(a)

Interpretation:

The peptide Gly−Leu−Val, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide Gly−Leu−Val is neutral as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 1

There will be no charge on the peptide, Gly−Leu−Val at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide Gly−Leu−Val is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 2

Figure 1

This tripeptide contains one amino group and one carboxylic group. So, this amino acid is neutral in nature. The amine group of glycine having pKa equals to 9.60 remains in the protonated form at pH=6. On the other hand, carboxylic group of valine having pKa equals to 2.32 remains in the carboxylate form at pH=6 as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 3

Figure 2

Therefore, the net charge on the peptide, Gly−Leu−Val remains zero at pH=6.

Conclusion

The peptide Gly−Leu−Val is neutral and no net charge is present on this peptide.

Interpretation Introduction

(b)

Interpretation:

The peptide, Leu−Trp−Lys−Gly−Lys, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide, Leu−Trp−Lys−Gly−Lys is basic as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 4

The net charge on the peptide, Leu−Trp−Lys−Gly−Lys is +3 at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide, Leu−Trp−Lys−Gly−Lys is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 5

Figure 3

This given peptide contains three amino group in its chain and one carboxylic group. So, this amino acid is basic in nature. All the amine group of the given peptide having value of pKa greater than pH=6, so, the amine group remains in the protonated form. On the other hand, carboxylic group of lysine having pKa equals to 2.18 remains in the carboxylate form at pH=6 as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 6

Figure 4

Therefore, the net charge of +3 is present on the peptide, Leu−Trp−Lys−Gly−Lys at pH=6.

Conclusion

The peptide, Leu−Trp−Lys−Gly−Lys is basic in nature and +3 charge is present on this peptide.

Interpretation Introduction

(c)

Interpretation:

The peptide, N−acetyl−Asp−Val−Ser−Arg−Arg, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide N−acetyl−Asp−Val−Ser−Arg−Arg is neutral as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 7

There will be no charge on the peptide, N−acetyl−Asp−Val−Ser−Arg−Arg at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide N−acetyl−Asp−Val−Ser−Arg−Arg is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 8

Figure 5

This given peptide contains two amino groups in the side chain and two carboxylic groups. So, this amino acid is neutral in nature. All the amine groups of this peptide having pKa greater than pH=6, so, amine groups remain protonated. On the other hand, carboxylic group of arginine and aspartic acids having pKa smaller than pH=6 and remains in the carboxylate form as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 9

Figure 6

Therefore, the net charge on the peptide, N−acetyl−Asp−Val−Ser−Arg−Arg remains zero at pH=6.

Conclusion

The peptide N−acetyl−Asp−Val−Ser−Arg−Arg is neutral and no net charge is present on this peptide.

Interpretation Introduction

(d)

Interpretation:

The peptide Glu−Lys−Asp−Ala−Phe−Ile, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide Glu−Lys−Asp−Ala−Phe−Ile is acidic in nature as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 10

The charge present on the peptide, Glu−Lys−Asp−Ala−Phe−Ile is −2 at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide Glu−Lys−Asp−Ala−Phe−Ile is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 11

Figure 7

This given peptide contains two amino groups in the side chain and four carboxylic groups. So, this amino acid is acidic in nature. All the amine groups of this peptide having pKa greater than pH=6, so, amine groups remain protonated. On the other hand, carboxylic group of the peptide is having pKa value smaller than pH=6 and remains in the carboxylate form as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 12

Figure 8

Therefore, the net charge on the peptide, Glu−Lys−Asp−Ala−Phe−Ile is −2 at pH=6.

Conclusion

The peptide Glu−Lys−Asp−Ala−Phe−Ile is acidic and −2 net charge is present on this peptide.

Answer 6

Chapter 27, Problem 27.10P

Interpretation Introduction

(a)

Interpretation:

The peptide Gly−Leu−Val, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide Gly−Leu−Val is neutral as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 1

There will be no charge on the peptide, Gly−Leu−Val at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide Gly−Leu−Val is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 2

Figure 1

This tripeptide contains one amino group and one carboxylic group. So, this amino acid is neutral in nature. The amine group of glycine having pKa equals to 9.60 remains in the protonated form at pH=6. On the other hand, carboxylic group of valine having pKa equals to 2.32 remains in the carboxylate form at pH=6 as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 3

Figure 2

Therefore, the net charge on the peptide, Gly−Leu−Val remains zero at pH=6.

Conclusion

The peptide Gly−Leu−Val is neutral and no net charge is present on this peptide.

Answer 7

Chapter 27, Problem 27.10P

Interpretation Introduction

(a)

Interpretation:

The peptide Gly−Leu−Val, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Answer 8

Expert Solution

Answer to Problem 27.10P

The peptide Gly−Leu−Val is neutral as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 1

There will be no charge on the peptide, Gly−Leu−Val at pH=6.

Answer 9

Expert Solution

Answer 10

Expert Solution

Answer 11

Expert Solution

Answer 12

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide Gly−Leu−Val is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 2

Figure 1

This tripeptide contains one amino group and one carboxylic group. So, this amino acid is neutral in nature. The amine group of glycine having pKa equals to 9.60 remains in the protonated form at pH=6. On the other hand, carboxylic group of valine having pKa equals to 2.32 remains in the carboxylate form at pH=6 as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 3

Figure 2

Therefore, the net charge on the peptide, Gly−Leu−Val remains zero at pH=6.

Answer 13

Conclusion

The peptide Gly−Leu−Val is neutral and no net charge is present on this peptide.

Answer 14

Interpretation Introduction

(b)

Interpretation:

The peptide, Leu−Trp−Lys−Gly−Lys, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide, Leu−Trp−Lys−Gly−Lys is basic as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 4

The net charge on the peptide, Leu−Trp−Lys−Gly−Lys is +3 at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide, Leu−Trp−Lys−Gly−Lys is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 5

Figure 3

This given peptide contains three amino group in its chain and one carboxylic group. So, this amino acid is basic in nature. All the amine group of the given peptide having value of pKa greater than pH=6, so, the amine group remains in the protonated form. On the other hand, carboxylic group of lysine having pKa equals to 2.18 remains in the carboxylate form at pH=6 as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 6

Figure 4

Therefore, the net charge of +3 is present on the peptide, Leu−Trp−Lys−Gly−Lys at pH=6.

Conclusion

The peptide, Leu−Trp−Lys−Gly−Lys is basic in nature and +3 charge is present on this peptide.

Answer 15

Interpretation Introduction

(b)

Interpretation:

The peptide, Leu−Trp−Lys−Gly−Lys, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Answer 16

Expert Solution

Answer to Problem 27.10P

The peptide, Leu−Trp−Lys−Gly−Lys is basic as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 4

The net charge on the peptide, Leu−Trp−Lys−Gly−Lys is +3 at pH=6.

Answer 17

Expert Solution

Answer 18

Expert Solution

Answer 19

Expert Solution

Answer 20

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide, Leu−Trp−Lys−Gly−Lys is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 5

Figure 3

This given peptide contains three amino group in its chain and one carboxylic group. So, this amino acid is basic in nature. All the amine group of the given peptide having value of pKa greater than pH=6, so, the amine group remains in the protonated form. On the other hand, carboxylic group of lysine having pKa equals to 2.18 remains in the carboxylate form at pH=6 as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 6

Figure 4

Therefore, the net charge of +3 is present on the peptide, Leu−Trp−Lys−Gly−Lys at pH=6.

Answer 21

Conclusion

The peptide, Leu−Trp−Lys−Gly−Lys is basic in nature and +3 charge is present on this peptide.

Answer 22

Interpretation Introduction

(c)

Interpretation:

The peptide, N−acetyl−Asp−Val−Ser−Arg−Arg, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide N−acetyl−Asp−Val−Ser−Arg−Arg is neutral as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 7

There will be no charge on the peptide, N−acetyl−Asp−Val−Ser−Arg−Arg at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide N−acetyl−Asp−Val−Ser−Arg−Arg is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 8

Figure 5

This given peptide contains two amino groups in the side chain and two carboxylic groups. So, this amino acid is neutral in nature. All the amine groups of this peptide having pKa greater than pH=6, so, amine groups remain protonated. On the other hand, carboxylic group of arginine and aspartic acids having pKa smaller than pH=6 and remains in the carboxylate form as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 9

Figure 6

Therefore, the net charge on the peptide, N−acetyl−Asp−Val−Ser−Arg−Arg remains zero at pH=6.

Conclusion

The peptide N−acetyl−Asp−Val−Ser−Arg−Arg is neutral and no net charge is present on this peptide.

Answer 23

Interpretation Introduction

(c)

Interpretation:

The peptide, N−acetyl−Asp−Val−Ser−Arg−Arg, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Answer 24

Expert Solution

Answer to Problem 27.10P

The peptide N−acetyl−Asp−Val−Ser−Arg−Arg is neutral as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 7

There will be no charge on the peptide, N−acetyl−Asp−Val−Ser−Arg−Arg at pH=6.

Answer 25

Expert Solution

Answer 26

Expert Solution

Answer 27

Expert Solution

Answer 28

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide N−acetyl−Asp−Val−Ser−Arg−Arg is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 8

Figure 5

This given peptide contains two amino groups in the side chain and two carboxylic groups. So, this amino acid is neutral in nature. All the amine groups of this peptide having pKa greater than pH=6, so, amine groups remain protonated. On the other hand, carboxylic group of arginine and aspartic acids having pKa smaller than pH=6 and remains in the carboxylate form as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 9

Figure 6

Therefore, the net charge on the peptide, N−acetyl−Asp−Val−Ser−Arg−Arg remains zero at pH=6.

Answer 29

Conclusion

The peptide N−acetyl−Asp−Val−Ser−Arg−Arg is neutral and no net charge is present on this peptide.

Answer 30

Interpretation Introduction

(d)

Interpretation:

The peptide Glu−Lys−Asp−Ala−Phe−Ile, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Expert Solution

Answer to Problem 27.10P

The peptide Glu−Lys−Asp−Ala−Phe−Ile is acidic in nature as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 10

The charge present on the peptide, Glu−Lys−Asp−Ala−Phe−Ile is −2 at pH=6.

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide Glu−Lys−Asp−Ala−Phe−Ile is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 11

Figure 7

This given peptide contains two amino groups in the side chain and four carboxylic groups. So, this amino acid is acidic in nature. All the amine groups of this peptide having pKa greater than pH=6, so, amine groups remain protonated. On the other hand, carboxylic group of the peptide is having pKa value smaller than pH=6 and remains in the carboxylate form as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 12

Figure 8

Therefore, the net charge on the peptide, Glu−Lys−Asp−Ala−Phe−Ile is −2 at pH=6.

Conclusion

The peptide Glu−Lys−Asp−Ala−Phe−Ile is acidic and −2 net charge is present on this peptide.

Answer 31

Interpretation Introduction

(d)

Interpretation:

The peptide Glu−Lys−Asp−Ala−Phe−Ile, is to be classified as the acidic, basic, or neutral. The net charge on the peptide at pH=6 is to be stated.

Concept introduction:

Amino acids are classified as acidic, basic and neutral according to the functional group they possesses. Acidic amino acids are those which have one more than one carboxylic acid group in its side chain and basic amino acids are those which have one or more amino group present in their side chain. Isoelectric point of the amino acids is the pH of the dilute aqueous solution of the amino acid at which the total charge on all molecules of amino acid is zero.

Answer 32

Expert Solution

Answer to Problem 27.10P

The peptide Glu−Lys−Asp−Ala−Phe−Ile is acidic in nature as shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 10

The charge present on the peptide, Glu−Lys−Asp−Ala−Phe−Ile is −2 at pH=6.

Answer 33

Expert Solution

Answer 34

Expert Solution

Answer 35

Expert Solution

Answer 36

Explanation of Solution

Peptides are classified as acidic, basic, or neutral according to the amino acids they contain. If they contain unbalanced basic amino acid then they are considered as basic peptide and if they contain unbalanced acidic amino acid then they are considered as basic peptides. If the basic and acidic amino acids are balanced or not at all present in the peptide then it is considered as neutral peptide.

The given peptide Glu−Lys−Asp−Ala−Phe−Ile is shown below.

ORGANIC CHEMISTRY SAPLING ACCESS + ETEX, Chapter 27, Problem 27.10P , additional homework tip 11

Figure 7

This given peptide contains two amino groups in the side chain and four carboxylic groups. So, this amino acid is acidic in nature. All the amine groups of this peptide having pKa greater than pH=6, so, amine groups remain protonated. On the other hand, carboxylic group of the peptide is having pKa value smaller than pH=6 and remains in the carboxylate form as shown below.