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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The amino acid arginine ionizes according to the following scheme: (a) Calculate the isoelectric point of arginine. You can neglect contributionsfrom form I. Why?(b) Calculate the average charge on arginine when pH = 9.20.(c) Is the value of average charge you calculated in part b reasonable, giventhe pI you calculated in part a? Explain your answer.
Protein A is made up of a single polypeptide chain; The molecular mass of A is 20,000 Da; the A molecule has 2 tryptophan residues, 5 tyrosine residues, and no disulfide bonds. Calculate what absorbance (at 280 nm) a solution of protein A will have at a concentration of 1.0 mg / mL, in a 1 cm cell. Write the calculations you have done.
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?
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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- The 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_forwardDraw the structural form of valine that predominates in solution at each of the following ph values: a. ph<pi ; b. pl ; c. ph>pi pk values: pk 1=2.2 ; pk2 = 9.7 Do also for asp (1.88, 9.60, 3.65) and lys (2.88, 8.95, 10.53)arrow_forward*H3N -Č-H CH2 он Tyrosine a. Draw the structures of tyrosine as different pH values. Please refer to the lecture notes for the pKa values b. Identify the structures that exist at pH 2 c. Solve for the plarrow_forward
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- Which intermolecular forces are important in acetic acid, CH3 –(C=0)-oh? A particular amino acid contains a- CHNH3+ group. Is this amino acid more likely to be found on the inside or the outside of the folded protein? Briefly explain. The addition of ethanol, CH3CHOH, t an aqueous solution lowers the surface tension of the solution. Predict whether adding ethanol to an aqueous protein solution will tend to stabilize or unfold the protein. Briefly explain.arrow_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_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 calculations b. Draw the structure of the amino acid at the pH determined in question 1arrow_forward
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