Q5. Each ionizable group of an amino acid can exist in one of two states, charged or neutral. Theelectric charge on the functional group is determined by the relationship between its pka andthe pH of the solution. This relationship is described by the Henderson-Hasselbalch equation.(a) Histidine has three ionizable functional groups. Write the equilibrium equations for its threeionizations and assign the proper pKa for each ionization. Draw the structure of histidinein each ionization state. What is the net charge on the histidine molecule in each ionizationstate?(b) Draw the structures of the predominant ionization state of histidine at pH 1, 4, 8, and 12.Note that the ionization state can be approximated by treating each ionizable groupindependently.(c) What is the net charge of histidine at pH 1, 4, 8, and 12? For each pH, will histidine migratetoward the anode (+) or cathode (-) when placed in an electric field?

Amino acids are simply an alpha-carbon bonded to 4 groups. The 4 groups are;an alpha-carboxyl group…

Answered: Q5. Each ionizable group of an amino…

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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What is the molecular basis for the observation that the overall charge on a protein becomes increasingly positive as pH drops and more negative as pH increases?
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
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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. (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-Gln- 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 (a) Which of the three peptides would elute first from a gel filtration column? (b) Which of the three peptides would migrate the fastest on SDS-PAGE (c) Which of the three peptides could be…
Can you please explain how to solve this problem?
Please draw titration curves for peptide HFDTYA and HEKDGQ, and calculate the pl for each. Usethis information to explain why the peptide HFDTYA has low solubility and HEKDGQ has a highersolubility in bulk water at pH = 7.
A protein has a dissociation equilibrium constant equal to 4.0um. What is the concentration of free ligand when the fraction of bound sites is 0.7
1. Make a series (at least 3) of drawings to show the three dehydration synthesis reactions that take place between the two Fatty Acids, the Phosphate Head and the Glycerol. Show the water molecules made. a) Label the following on the completed phospholipid: hydrophilic and hydrophobic parts of the molecule, fatty acids, phosphate group, and glycerol. b) Compare the structure of the phospholipid to that of a triglyceride. How are the two molecules Similar? How are they different? 2. Use the following vocabulary to label and draw a cell membrane: cytoplasm (cell lumen) extra-cellular fluid hydrophobic hydrophilic polar head non-polar tails a) How many O-H groups are there? And are the O-H areas of sucrose polar or non-polar? b) What is the term that is used to discuss how tightly or loosely an atom's nucleus has a hold of its valence electrons?
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. (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…
20. The dissociation constant of protein Z for ligand Y is: 10 micromolar. What fraction of the ligand is bound at ligand concentration = 5 micromolar?
3
Explain what the meaning of these distances is (e.g., from where to where?)Crystal structure of human monocyte chemotactic protein-2

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