Biochemistry: Concepts and Connections (2nd Edition)
2nd Edition
ISBN: 9780134641621
Author: Dean R. Appling, Spencer J. Anthony-Cahill, Christopher K. Mathews
Publisher: PEARSON
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Textbook Question
Chapter 2, Problem 15P
The anno acid arginine ionizes according to the following scheme:
a. Calculate the isoelectric point of arginine. You can neglect contributions from form l. Why?
b. Calculate the average charge on arginine when pH = 9.20. (Hint: Find the average charge for each ionizable group and sum these together)
c. Is the value of average charge you calculated in part b reasonable, given the pl you calculated part a? Explain your answer.
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For the following pentapeptides: Ser-Glu-Gly-His-Ala and Gly-His-Ala-Glu-Ser
A. Compute their isoelectric pH (pI). Show full solution. Use standard pKa values.
B. Do these peptides with the same amino acid composition have different net charges at pH 7.0? Explain briefly.
C. Would you expect the titration curves of the two peptides to differ? Why or Why not?
A peptide with an amino acid sequence and molecular mass (1028.5193 Da) is given below
HVMTLNLGEΚ
Determine the maximum number of positive charges of this peptide.
а.
b.
Determine the possible m/z ratio of this peptide at different charge states.
The amino acid arginine ionizes according to the following scheme:
NH₂
I
C=N
I
ΝΗ
Part A
pl =
Submit
H (CH₂)3
H-N-C-COOH
II
HH
1
[ΠΙ ΑΣΦ
H
H
Calculate the isoelectric point of arginine.
Express your answer using three significant figures.
Request Answer
pk-2.17
-H*
+H*
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NH₂
C=N
ΝΗ
H (CH₂)3
1
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H
H-N-C-COO-
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H H
11
H
pk-8.99
-H*
+H*
NH₂
I
C=N
I
ΝΗ
T
(CH₂)3
H
H
H₂N-C-COO-
I
H
pk - 12.5
-H*
+H*
NH₂
C=N=H
NH
I
(CH₂)3
H₂N-C-COO-
I
H
IV
Chapter 2 Solutions
Biochemistry: Concepts and Connections (2nd Edition)
Ch. 2 - Suppose a chloride ion and a sodium ion are...Ch. 2 - Draw two different possible hydrogen-bonding...Ch. 2 - Prob. 3PCh. 2 - 4. What is the pH of each of the following...Ch. 2 - Prob. 5PCh. 2 - The weak acid HA is 2% ionized (dissociated) in a...Ch. 2 - 7. Calculate the pH values and draw the titration...Ch. 2 - What is the pH of the following buffer mixtures?...Ch. 2 - a. Suppose you wanted to make a buffer of exactly...Ch. 2 - Prob. 10P
Ch. 2 - You need to make a buffer whose pH is 7.0, and you...Ch. 2 - Describe the preparation of 2.00 L of 100 glycine...Ch. 2 - Carbon dioxide is dissolved in blood (pH 7.4) to...Ch. 2 - What is the molecular basis for the observation...Ch. 2 - The anno acid arginine ionizes according to the...Ch. 2 - It is possible to make a buffer that functions...Ch. 2 - A student is carrying out a biological preparation...Ch. 2 - Histidine is an amino acid with three titratable...Ch. 2 - Prob. 19PCh. 2 - A biochemical reaction takes place in a 1.00 ml...Ch. 2 - Is RNA-binding enzyme RNase A more likely to have...Ch. 2 - Consider a protein in which a negatively charged...Ch. 2 - Prob. 23PCh. 2 - Prob. 24P
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- You are given 0.5 M solution of the amino acid Arginine. pK1 (α-carboxyl group) = 2.17 pK2 (α- amino group) = 9.03 and pK3 (guanidine group) = 12.48 Determine the pH of the solution if you add 15 mL 0.25 M HCl to 10 mL of the 0.5 M Arginine. Assume that Arginine is in isotonic state. Show all calculations b. Draw the structure of the amino acid at the pH determined in question 1arrow_forwardYou are given 0.5 M solution of the amino acid Arginine. pK1 (α-carboxyl group) = 2.17 pK2 (α- amino group) = 9.03 and pK3 (guanidine group) = 12.48 Determine the pH of the solution if you add 15 mL 0.25 M HCl to 10 mL of the 0.5 M Arginine. Assume that Arginine is in isotonic state. Show all calculationsarrow_forwardConsider a peptide with the sequence Ala-Glu-Arg-Leu. Assume the ionizable groups have the pKa values listed in Table 2.1 of your text. (a) Draw the predominant ionic form of the peptide at pH 7.4. (b) Determine the net charge of the predominant form of the peptide at pH 7.4. (c) Calculate the pI of the peptide.arrow_forward
- A peptide has the sequence: Glu–His–Trp–Ser–Gly–Leu–Arg–Pro–Gly1. What would be the net charge of the molecule at pH a) 3, b) 8, and c) 11? (Use pKa values. Do not calculate the value per se, but instead estimate considering only fully protonated, or deprotonated states. Then estimate the pI for this peptide. Show full, clear and complete procedurearrow_forwardK₁ = α [H+][A-] [HA] [A-] pH = pK+log [HA] 1-1 The Amino acid Arginine ionizes according to the scheme below. Calculate the isoelectric point of Arginine and the average charge on arginine when pH = 9.2. NH2 H C=N NH pka-2.17 -H' NH2 H C=N H NH PK-8.99 -H +H* H (CH2)3 H-N-C-COOH | H H +H* H (CH2)3 H-N-C-coo- H H Ans: 10.75; +0.38 NH2 NH2 H C=N C=N-H H NH PK-12.5 -H NH | +H* (CH2)3 H₂N-C-COO- | H III (CH2)3 H₂N-C COO- H IVarrow_forwardThe β chains of HbA and HbS were treated with trypsin, and the sequence of the N-terminal tryptic peptides are as given below. Do these peptides separate from each other in an electric field if the pH is 7.0? Explain in detail the reasoning behind your answer and include your calculations for the charge of each peptide in your answer.arrow_forward
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