5For the peptide structure in #3, (ASP-ALA-THR-LYS-GLY), use the chart at the end of this HW set to:A. Determine the net charge of the pentapeptide at pH 3, 4, 7, 10 and 11.B. Estimate the isoelectric point, pl, for this 5-amino acid peptide Amino AcidAlanineAmine+ Arginine2.352.01Asparagine 2.02COO Aspartic Acid 2.10SHS Cysteine 2.05COO-Glutamic Acid 2.10Glutamine 2.17Glycine2.35Amine Histidine1.77Isoleucine2.322.332.18Methionine 2.28Phenylalanine 2.582.002.21Threonine 2.09Tryptophan 2.382.202.29LeucineAmine LysineProlineSerinepk Values for amino acidspk, (a-COOH)a-carboxylic acidOH → 0 TyrosineValinepk. (a-NH₂)a-amine9.879.048.809.8210.259.479.139.789.189.769.748.959.219.2410.609.159.109.399.119.72pka (side)Side chain12.483.868.004.076.1010.5310.07Amino acids with ionizable R groups (pK's)carboxylic acid COOH PK 'sother weak acids with pk'sprimary amine NH₂ pk'sweak tertiary amine N pK,

The proteins are composed of twenty naturally occurring amino acids. The amino acids can be…

Answered: 5 For the peptide structure in #3,…

Biochemistry

9th Edition

ISBN:9781319114671

Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Publisher:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.

Chapter1: Biochemistry: An Evolving Science

Section: Chapter Questions

Problem 1P

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5. Refer to Model 2 for information relevant to this question. A sample of the peptide Lys-Glu-Ser has a net charge of zero between what two pH values? What is the pl of Lys-Glu-Ser? Model 2: The pl of a peptide is determined by examining the ionizable groups. The protonated and unprotonated forms of each ionizable group are in equilibrium. Consider the peptide Lys-Glu-Ser shown below at pH 7.2. The complete structure is on on the left and a stylized structure with just the ionizable groups is on the right. While the N-terminal is depicted as protonated, a sample of Lys-Glu-Ser is composed of a population of molecules and within that population some molecules contain a non-protonated N-terminal group at pH 7.2. may H3N* COO- H3N-CH-CIN-CH C N-CH C- H. pK 3.5 OH H. pK= 8.5 COO- CH2 CH2 CH2 NH, pK 10.0 pK 4.2 CH2 CH2 OH CH2 c=0
a. Suppose that you have the peptide Ala-Gly-Tyr-His-Leu and you treat it with FDNB and then 6M HCl. Draw the structures of all the products that you will have in solution (assume all reactions to go to completion).
1 Draw the following polypeptide: Met- Tyr-Val-Ser-Asn 2A Draw the hydrolysis of a dipeptide consisting of phenylaline and glutamic acid. 2B What are the fuctional group present in the side chains of the amino acids.( phenylalanine and glutamic acid) 2C are the sidechains in part 2B hydrophobic or polar 2D where would you expect to find them ( surface or interior of a protein) ? why ?
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4 This is a three-part question about a tripeptide. Answer all three sub-questions. The pKR of side chains of Tyr, and Lys is 10.46 and 10.54 respectively. The molecular weight of amino acids Ala, Lys, and Tyr in neutral form is 89.1, 146.2, and 181.2 Da, respectively. 1) Draw the chemical structure of the dominant form of tripeptide AKY at pH = 11.5, ensure you have the correct stereochemistry and ionization state of each functional group (Hint, lysine has a C-epsilon as the furthest carbon from C-alpha). 2) Calculate the pI of tripeptide AKY, assuming the terminal amino group has a pKa of 8.0, and the terminal carboxyl group has a pKa of 3.5 3) Calculate the molecular weight of AKY at pI
3-2.10
Shown is the electrophoretic profile of a pure protein ran at different pH values HH (+) (-) pH 5 pH 6.5 pH 7.4 pH 9.2 What is most likely the reason for the change in the position of the protein band at pH 9.2? A. deprotonation of internally located basic amino acid residues B. deprotonation of N-terminal amino acid C. deprotonation of an internally located basic amino acid, his D. deprotonation of acidic amino acids, glu and asp E. deprotonation of cys
13. Amino acid analysis of a seven residue long peptide gave Asp Leu Arg Met | Phe Met | Phe | Tyr (i) The PTH amino acid derivative released by Edman degradation was Tyr-PTH (ii) Trypsin treatment had no effect (iii) Cyanogen bromide treatment yielded a dipeptide, a tetrapeptide, and free Arg (iv) Brief chymotrypsin treatment yielded several products, including a dipeptide and a tetrapeptide. The amino acid composition of the tetrapeptide was Leu, Arg, and Met What is the amino acid sequence of this seven residue long peptide, and explain how you reached that conclusion?
6 (a) A decapeptide has the following amino acid composition: Ala2 , Arg, Cys, Glu, Gly, Leu, Lys, Phe, Val Partial hydrolysis yields the following tripeptides: Cys-Glu-Leu + Gly-Arg-Cys + Leu-Ala-Ala+ Lys-Val-Phe + Val-Phe-Gly. Reaction of the decapeptide with 2,4-dinitrofluorobenzene yields 2,4-dinitrophenylysine. From the experimental data, deduce the primary structure of the decapeptide. (b) Suggest a scheme you will follow to synthesize the dipeptide Ala-Gly
Determine the pI of the peptide H2N-Ala-Lys-Ser-Arg-COOH at pH 11, please explain why some pKas are used in the solution of the problem while others are not.
3
7. Identify the primary structure of a hexapeptide containing five different amino acids if the following smaller peptides are among the partial hydrolysis products: Gly-Cys, Ala-Ser, Ala-Gly, and Cys-Val-Ala

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5 For the peptide structure in #3, (ASP-ALA-THR-LYS-GLY), use the chart at the end of this HW set to: A. Determine the net charge of the pentapeptide at pH 3, 4, 7, 10 and 11. B. Estimate the isoelectric point, pl, for this 5-amino acid peptide