2.| Calculate the overall charge (pH 7) on the following three polypeptides and answer thequestions below. Assume the following pKa values: N-terminal –NH3®, 7.0; all -COOH groups, 4.0;Arg, 12.5; Cys, 8.4; His, 6.0; Lys, 10.0; Tyr, 10.0.(A)Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys–Pro–Val–Gly–Lys–Lys–Arg-Arg-Pro-Val-Lys–Val-Tyr-Pro-Asp-Ala-Gly- Glu-Asp-GIn– Ser-Ala-Glu-Ala-Phe-Pro-Leu-Arg-Glu-Phe(B)Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Ala-Pro-Val-Gly-Glu-Glu–Cys-Asp-Pro-Val-Glu–Val–Tyr-Pro-Asp-Ala-Gly-Glu-Asp-Gln-Ser-Ala-Glu-Ala-Phe-Pro-Leu-Glu-Phe-Cys-Ser-Tyr-Ser-Met-Glu–His-Phe-Asp-Trp-Gly-Asp-Pro-Val-Gly-Pro-Asp-Ala-Gly-Asp-Gln-Pro-Val–Gly–Glu-Glu-Cys-Asp-Pro–Val-Glu–Val–Tyr-Pro-Asp-Ala(C)Gly-Ser-Val-Arg-Asp-Pro-Val-Lys-Glu-Val-Tyr-Pro-Asp- Lys–Ala-Gly-Arg-Glu-Ser-Arg-Ala(d) Which of the three peptides would migrate the closest to the anode in isoelectric focusing?(e) Which of the above peptides would elute last from a gel filtration column?(f) Which of the three peptides would migrate the slowest on SDS-PAGE(g) Which of the three peptides would migrate the furthest away from the anode in isoelectric fo-cusing

Peptides are composed of amino acids and amino acids have ionizable groups. The alpha-amino (NH3+)…

Answered: 2. Calculate the overall charge (pH 7)…

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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3.) A mixture of amino acids was subjected to paper chromatography with six amino acid standards in order to determine its composition. After visualization using ninhydrin, the measured distances were as follows: A B с D E F G a.) What is the Rf value of each amino acid observed? X Distances: Solvent 10.3cm A 4.50cm B - 1.32cm C - 6.60cm D - 5.20cm E - 3.52cm F 8.70cm G - 10.26cm X1 - 9.72cm X2 - 4.3cm X3 7.1cm - b.) What are the possible components of the amino acid mixture? Answer can be up to two amino acids per component.
4. What is the net charge (approximately) on the polypeptide shown below at pH 12.5? Lys - Arg - Val-Cys - Glu
6. Using the charges you calculated above, plot the characteristics of alanine over a range of pH values. Connect the points by estimating what the charge should be at pH values where you lack data. It is possible to calculate the charge at any pH, but if you understand the relationships presented here you will be able to make estimates quickly and easily. +2 +1.5 +1 - +0.5- -0.5 - -1- -1.5 - 7. 6. 11 13 14 pH of solution 7. Aspartic acid has a side chain bearing a carboxylic acid group; its pK, is 4. The a-amino and a-carboxylic groups have pKa values similar to those of alanine. Determine the net charge on aspartic acid at the following pH values: pH 1 pH 2 pH 4 pH 9 pH 13 Net charge of molecules 2.
13.2
Given this: Protein Isoelectric pH Molecular weight (kDa) Ovalbumin 4.6 45 Insulin 5.4 5.7 Fibrinogen 5.8 340 Y-globulin 6.6 160 Collagen 6.6 115 Hemoglobin (monomer) 7.1 16 Myoglobin 7.0 16.7 What is the appearance after visualization of a protein mixture containing the seven proteins above if 2D gel electrophoresis is done?
1. Hypoxanthine is an unusual nitrogenous base that can be formed from adenosine; it is not normally found in nucleic acids. Hypoxanthine has a single ionizable group with a pKa of 8.7. If you dissolved hypoxanthine in an aqueous solution at pH 7.0, would this ionizable group be protonated or deprotonated?
1. What is the isoelectric point (pI) of lysine which has pKa values of 2.1 for the α carboxyl group, 9.7 for the α amino group and 10.5 for the side chain amino group? 2. Which of the following is most likely to be found on the exterior of a protein? A) Pro B) Trp C) Ser D) Glu 3. The type of reaction that forms a peptide bond is A) Elimination B) Hydrolysis C) Nucleophilic substitution D) Condensation
A sample mixture consists of three proteins with the following properties: Protein A MW (kDa) 200 Amino acid composition 40% nonpolar, 60% polar B 45 20% nonpolar, 80% polar C 98 85% nonpolar, 15% polar IpH 9 3 5 1. If the mixture is subjected to ammonium sulfate precipitation, which protein will precipitate out first? [Select] 2. If the mixture is subjected to isoelectric focusing, which protein will stop moving nearest to the positive electrode? [Select] 3. If the mixture is subjected to cation-exchange chromatography using a buffer at pH 7, which protein will bind to the resin? [Select] 4. If the mixture is subjected to SDS-PAGE, which protein will be at the bottommost portion of the gel? [Select] * Previous Nex
1.0 0.9 Z 0.8 15. A pharmaceutical company studied the binding of three different compounds, X, Y, and Z, to a particular protein of interest. For each compound, the fractional saturation (v) was determined as a function of concentration. The results are shown in the figure. Which of the three compounds has the strongest affinity for the protein? Explain. 0.7 X 0.6 > 0.5 0.4 0.3 0.2 0.1 0.0 Y 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 L(μM)
1) Find the pH of 0.1 M of the differnet forms histidine species. (See image for equation and pKa values) 2) What is the principal specis at pH 1, pH 5, pH 8, and pH 11?
3. In a solution of alanine molecules, approximately what fraction of the alanine will exist as the zwitterion at pH of 2.34? What would be the average net charge of a solution of alanine molecules at pH 2.34? 50% will exist as the zwitterion and 50% will exist as the fully protonated (COOH/ NH3+) form. The average net charge of this solution would be +0.5.

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2. Calculate the overall charge (pH 7) on the following three polypeptides and answer the questions below. Assume the following pKa values: N-terminal –NH3®, 7.0; all -COOH groups, 4.0; Arg, 12.5; Cys, 8.4; His, 6.0; Lys, 10.0; Tyr, 10.0.