The figure shows an example of a thermal denaturation plot.The melting temperature (Tm) is the midpoint of thetemperature range over which denaturation occurs.Percent unfolded10080604020020Tm4060Temperature (°C)80100 Suppose that the thermal denaturation experiment on the protein with the Met to Lys mutation took place at pH 10.0.Would the mutation have a greater or lesser impact on stability at pH 10.0 compared to pH 3.0?no change, because the Lys side chain pK, is above 10.0 so the side chain remains chargedlesser, because a less acidic environment contributes to general protein stabilitylesser, because a greater fraction of Lys can remain buried in the core at pH 10.0greater, because high pH values destabilize proteins

pKa is the pH at which a weak acid is 50% dissociated. Changes in pH affect the ionisation of…

Answered: Suppose that the thermal denaturation…

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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Do you expect a Pro → Gly mutation in a surface-loop region of a globular protein to be stabilizing or destabilizing? Assume the mutant folds toa native-like conformation. Explain your answer in terms of the predictedenthalpic and entropic effects of the mutation on the ∆G for protein foldingcompared to ∆G of folding for the wild-type protein
(c) The tube and cylinder diagram to the right illus- trates schematically the potassium channel protein from a bacterium. This channel protein consists of four identical polypeptide chains each comprised of 119 residues. The cyan ribbon illustrates only two of the polypeptide chains. The relative positions of 4 α-helices, one from each poly- peptide chain, are shown as cylinders. The red sphere in the central part of the diagram shows the position of a potas- sium ion identified by X-ray structure analysis. A cesium ion (green sphere) was also found to be stabilized in the same position when cesium chloride was introduced into the crys- tals. The cylinders each represent an α-helix running from Tyr62 to Thr74. Considering the position of the potassium ion, in- dicate on one of the cylinders at which end of the cylinder residue Tyr62 is found and at which end residue Thr74 is found. Explain the basis of your answer? Ala23 Thr119 (d) The N- and C-terminal residues of one of the…
The amide hydrogen atoms of peptide bonds within proteins can exchange with protons in the solvent. In general, amide hydrogen atoms in buried regions of proteins and protein complexes exchange more slowly than those on the solvent-accessible surface do. Determination of these rates can be used to explore the proteinfolding reaction, probe the tertiary structure of proteins, and identify the regions of protein–protein interfaces. These exchange reactions can be followed by studying the behavior of the protein in solvent that has been labeled with deuterium ( ²H), a stable isotope of hydrogen. What two methods described in this chapter could be readily applied to the study of hydrogen– deuterium exchange rates in proteins?
Consider the phenolic hydroxyl group of a particular Tyr residue in a protein. Suppose the hydroxyl group in the unfolded protein in aqueous solution, where the group is exposed to H2O, has a pKa of 10.0. If that group is found in a hydrophobic environment in the interior of the protein when the protein is folded into its native tertiary structure, would you expect the pKa of the phenolic hydroxyl to be higher or lower in the folded protein interior than in H2O? Explain your reasoning.
Suppose you have a solution of a protein, which contains a specific Tyr residue that has an actual (measured) pKa of 8.8. The protein binds a ligand by several noncovalent interactions, one of which is a hydrogen bond in which the Tyr phenolic hydroxyl group must serve as a hydrogen bond donor. Calculate the percentage of the protein molecules in which that tyrosyl residue's phenolic hydroxyl group could serve as a hydrogen bond donor at pH 8.5
Given the following diagram of how protein AWESOME1 binds to it's target DNA, describe the potential effects of each of the 5 mutations shown below. The wild-type sequence of a helix #1 is also shown in the blue box, and all the mutations are in helix #1 (see numbers for identifying particular residues). a helix #1 R(1)-V-I-L-Y-F-W-I-M-Y-F-S-H-Y-W-R(16) #1 Predict the consequence of the following mutations: 1) Arg(1) to Glu 2) Arg(1) to Ala 3) Phe(6) to lle 4) Trp(7) to Phe 5) Met(9) to Pro in
A researcher has synthesized two peptides and needs to confirm whether the peptides were synthesized with the correct sequence using mass spectrometry. What is the sequence of the b4 and y7 ions for peptide GAMECHANGER? The peptide SLISRAEFLAGVRVGV is digested with trypsin. Then the products of the digestion are subjected to ESI TOF-MS in positive ion mode with the peptides in a pH 2 solution. What peptide fragments will result and what are their m/z?

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