2. A mutation that changes an alanine residue in the interior of a protein to valine (A157 → V157) is found to lead to aloss of proper folding and activity. However, proper folding and activity are regained when a second mutation at adifferent position changes a leucine residue to glycine (L185 G185). Based on these observations, you→hypothesize that amino acid residues 157 and 185 are spatially close to each other in the folded and activeprotein. How does your hypothesis explain the data, that the double mutant (A¹57 → V157; L185 → G185) has activitythat the single mutant (A¹57 → V157) lacks?

Different protein gain its three dimensional structure after folding, which occurs according to the…

Answered: 2. A mutation that changes an alanine…

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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Similar questions

To better understand the effects of palmitoylation on protein X, researchers want to chemically attach a palmitic acid at a specific position in this protein. The researchers first try to feed cells with palmitic acid or an amino acid with a C16 side chain. Neither of the initial experiments is successful in helping the researchers learn more about the biological role of palmitoylated protein X. Why? Suggest a strategy to specifically incorporate a palmitoylation site into protein X.
Remembering that the amino acid side chains projecting from each polypeptide backbone in a β sheet point alternately above and below the plane of the sheet, consider the following protein sequence: Leu-Lys-Val-Asp-Ile-Ser-Leu-Arg- Leu-Lys-Ile-Arg-Phe-Glu. Do you find anything remarkable about the arrangement of the amino acids in this sequence when incorporated into a β sheet? Can you make any predictions as to how the β sheet might be arranged in a protein?
On average, how many phosphoanhydride bonds (P;-P; bonds) are directly hydrolyzed in thecourse of synthesizing a 200 amino acid protein? Assume that you begin with the mature mRNA,ribosomal subunits, tRNAs, free amino acids, and all necessary factors.
Consider the hypothetical serine protease in the image, which shows the specificity pockets. The S1 pocket is small and hydrophobic, the S2 pocket is deep and hydrophobic, and the S1' pocket has an aspartate residue in the bottom. If the amino acids involved are K, W, and G, which pair is joined by the peptide bond that will be cleaved by the protease? MAKE SURE YOUR CHOICE REFLECTS THE S1-S ORDER DESCRIBED. S1 Rs R1 Ri H. S2 S OGK OKAN OwG IZ IZ
Consider the peptide Asp-Lys-Phe-Glu-Asn-Tyr-Gln-Val-Cys. In a single beaker, you treat this peptide with 2 proteases. One protease cleaves at the N-terminus of aromatic R groups and the other cleaves at the C-terminus of polar, non-ionizable R groups. Following the enzymatic digestion, you want to separate your peptide fragments so that you can identify them. You choose to separate the fragments using an anion exchange column. Beginning at pH=6 you apply your peptide fragments to the column and you gradually decrease the pH of the column stopping the separation when the pH of the column equals 4. Omitting chemical structures, write the amino acid sequence of the peptide fragments that are produced from this digest. Write the order that these fragments will elute from the column (if at all). (Relevant pKa values are: 2.1, 3.8, 4.3, 8.3, 9.6, 10.1, and 10.5)
Consider the hypothetical serine protease in the image, which shows the specificity pockets. The S1 pocket has a glutamic acid in the bottom, the S2 pocket is small and hydrophobic, and the S1' pocket is deep and hydrophobic. Suggest a 3-amino acid sequence that this protease would cleave and indicate between which sites the peptide bond would be broken. S2 Which sequence would this protease cleave? O Leu-Val-Arg Arg-Val-Leu Val-Leu-Arg Val-Arg-Leu O Leu-Arg-Val O Arg-Leu-Val W Ma étv N 894
You have discovered a novel protein that has a pl = 5.5. To study the functional properties of this new protein your research group has made a mutant that contains two amino acid changes-namely, a surface Phe residue in the normal protein has been replace by His (side chain pk = 6.1), and a surface Gln has been replace by Glu (side chain pk. = 6.0). The pl of the mutant protein is predicted to be: A. Greater than the pl of the normal protein. B. Less than the pl of the normal protein. C. The same as the pl of the normal protein.
1. Consider the following α helix from myoglobin at pH 7. Gln-Gly-Ala-Met-Asn-Lys-Ala-Leu-Glu-His-Phe-Arg-Lys-Asp-Ile-Ala-Ala-Lys-Tyr(a) Label amino acids in the polypeptide above as follows: p for polar and uncharged, np for non polar, – for negatively charged, and + for positively charged.(b) How many complete turns are there in this helix?(b) Which side chains are likely to be on the side of the helix that faces the aqueous solvent? Why?(c) Which side chains are likely to face the interior of the protein? Why?
9. Shown below is a binding pocket for a protein with a ligand bound. The ligand interacts with a serine and a valine side chain. ligand a. Briefly explain, in terms of Ka, the effect of a mutation that replaces the serine residue with a valine residue. b. Briefly explain, in terms of Kd, the effect of a mutation that alters the ligand (as seen below) binding to the original, unmutated, binding site. :0: ligand 2
1. A pentapeptide has the sequence of H2N-Glu-His-Leu-Arg-Gly-COOH. a) What is the net charge of the peptide at pH 3, 8, and 11? (Use pka values for side chains and terminal amino and carboxyl groups in the table provided.) peptide. b) Estimate the pl for this pK, values Abbreviation/ symbol pk, M, (-COOH) (-NH5) (R group) pK; pKR Hydropathy Occurrence in index* proteins (%)* Amino acid pl Nonpolar, aliphatic R groups Glycine Alanine Proline Valine 2.34 -0.4 Gly G Ala A Pro P 75 9.60 5.97 7.2 89 115 2.34 9.69 10.96 6.01 6.48 5.97 1.8 1.6 4.2 3.8 4.5 7.8 5.2 1.99 117 131 Val V 2.32 2.36 9.62 9.60 6.6 9.1 Leucine Leu L 5.98 Isoleucine lle I 131 2.36 2.28 9.68 6.02 5.3 Methionine Met M 149 9.21 5.74 1.9 2.3 Aromatic R groups Phenylalanine Tyrosine Tryptophan 2.8 -1.3 3.9 3.2 Phe F 165 1.83 9.13 9.11 9.39 5.48 2.20 Tyr Y Trp W 181 10.07 5.66 204 2.38 5.89 -0.9 1.4 Polar, uncharged R groups Serine Ser S 105 2.21 6.8 9.15 9.62 5.68 5.87 5.07 5.41 5.65 -0.8 Threonine Thr T 119 2.11 -0.7 5.9…
The following amino acids that are often found inside globulin molecules are () A, Tyr B, Phe C, Asn D, Glu True of false 1. In the de novo synthesis of purine nucleotides and pyrimidine nucleotides, base rings are first synthesized and then corresponding nucleotides are formed with phosphoribose. () 2. Transcription is the process of transferring genetic information from DNA to RNA. DNA is synthesized under the catalysis of RNA polymerase, and the direction of synthesis is from the 5 'end to the 3' end. () 3. The change of protein conformation is caused by the breaking of covalent bonds within the molecule. () 4. In very high and very low pH solutions, amino acids exist mainly in non-ionic form. () 5. The active center of an enzyme usually consists of several amino acid residues adjacent to each other in the primary structure. ()
2. The mature form of TEM-1 ß-lactamase, an enzyme of 290 amino acid residues that hydrolyzes penicillin antibiotics. The protein has the following polar amino acid side chains: 18 Arg; 11 Lys; 6 His; 4 Tyr; 16 Asp; 20 Glu; 8 Asn; 5 Gln. Approximate pKa values 1.5 Arginine 12.5 Lysine 10.0 Histidine 6.5 OD 280nm Tyrosine 10.0 Aspartate or Glutamate 4.0 Terminal NH3+ 8.0 Terminal COOH 4.0 0.0 A 0.01 0.10 KCI B Volume (mL) The chromatogram above shows a typical result in the purification of TEM-1 ß-lactamase overex- pressed in E. coli cells. The protein is eluted from an anion exchange column at pH 6.25 with an increasing gradient of KCI. Fraction A is shown to correspond to native enzyme. Since Fraction B has the same amino acid sequence for the first 10 residues, the conclusion is that this fraction represents enzyme in which side chains of glutamine or asparagine residues have been hydrolyzed (deamidated). (a) ( ) What is the isoelectric point of the native enzyme? (b) ( ) Compared to…

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