What would the net charge be of a polypeptide with the sequence M-D-R-N-Q-K-R-W at pH 8? hint ionizable groups include N-terminus (pKa = 9.0), D (pKa = 3.9), R (pKa = 12.5), K %3D (pКa%3D 10.5) O +2 O -1 O +1

What would the net charge be of a polypeptide with the sequence M-D-R-N-Q-K-R-W at pH 8? hint ionizable groups include N-terminus (pKa = 9.0), D (pKa = 3.9), R (pKa = 12.5), K %3D (pКa%3D 10.5) O +2 O -1 O +1

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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Within a naturally-occurring polypeptide, under neutral pH conditions (pH = 7.0), which of the following amino acids always has a negatively charged carboxyl group? the first amino acid in the primary structure histidine lysine arginine the last amino acid in the primary structure
The bottom peptide segment is found in the secondary structure composed of anti-parallel - sheets. From the C-terminus of the peptide below, the sequence immediately after alternation contains the following amino acid residues (from N → C) A-F-R-M-Y-A. a) which side do you expect to face the solvent? Briefly explain your reasons NH, но Nterminus
What is the charge on the following peptide at standard biochemical pH? S-Y-D-F-K-I-V-F-L-L +2 -1 0 0 0-2 O +1
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…
a) The pl of a protein is 9.0. What will be the net charge (positive, negative or neutral) on the protein under the following conditions: A buffer with pH 9.0: A buffer with pH 7.0: A buffer with pH 10.0: b) Your protein is present in a sample buffer which has a pH 7.0. The sample is applied to an ANION EXCHANGE column. Will protein 1 bind to the beads on the column? Yes/No
Consider the positively charged amino acid lysine Lys2+ 21 COOH I H&N-C-H I pH 14 12 10 8 6 4 2 0 CH₂ I CH₂ I CH₂ I CH₂ T NH₂+ 0 Nelson p85 2.18 = 2.18 PK₁ Lys+ COO™ I H₂N-C-H H₂N-C-H ī I -----) 8.95 Lysº 8.95 pK₂ pka carboxyl = 2.19 pkaamino = 9.67 pka sidechain = 4.25 COO™ I CH₂ I CH₂ I CH₂ I CH₂ I NH₂¹ 1.0 2.0 Equivalents of OH added- COO™ I H₂N-C-H I 10.79 1 10.79 pk Isoelectric point Lys CH₂2 I CH₂ I CH₂ I CH₂ T NH₂ 3.0 +H3N NH3+ T CH₂ T CH₂ CH₂ CH₂ -COO™ H Lysine (Lys, K) Physiological pH = 7.4 < pl → Amino acid is positively charged at physiological pH 1. Consider glutamate in its fully protonated form (e.g. in a pH = 1 solution) 1) Draw all the forms of glutamate at various pH 2) Calculate the pl of this amino acid 3) Sketch a titration curve showing pH as a function of added [OH-] and locate the predominant forms of histidine in the curve STEPS: 1. Find the H atoms that can be removed on the molecule 2. Associated a pka value to each removable H. 3. Draw the Aa structure at:…
A researcher isolates a new protein and finds that it contains 0.755% serine by weight upon amino acid analysis. The molecular mass of serine is 105 g.mol-¹. What is the minimum molecular mass for the protein assuming only one Ser residue per protein molecule? mmin = The researcher estimates the molecular mass of the protein using gel electrophoresis. From this estimated molecular mass, the researcher concludes the protein contains 3 Ser residues. What is the estimated molecular mass of the protein as shown by gel electrophoresis? g.mol-¹ mest = g.mol-1
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…
Which of the following best describes how the secondary structure of a protein is formed? A B с D O=U a-helix H O=C N-H R-C-H C=0 H-N H-C-R O=C N-H R-C-H C=O H-N O-C N-H R-C-H C=O H-N N-H 0= H-C-R H-N C=O R-C-4 N-H O=C H-C-R 4-1 Ç=O R-C-H N-H 0=C H-C-R (=O R-C-H B-pleated sheet ionic bonds between the R groups of the polypeptide amino acids -Uh hydrogen bonds between the carboxyl and amino groups of non-adjacent amino acids covalent bonds between the carboxyl and amino groups of adjacent amino acids hydrogen bonds between the R groups of the polypeptide amino acids
blank 1 hydorgen or disulfide or covalent or ionic blank 2 heme nitrogen or O2 or distal histidine or promixmla histidine or heme iron blank 3 hydorgen or disulfide or covalent or ionic blank 4 heme nitrogen or O2 or distal histidine or promixmla histidine or heme iron