Do you expect a Pro → Gly mutation in a surface-loop region of a globularprotein 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 ΔG for protein foldingcompared to ΔG of folding for the wild-type protein.

A family of proteins known as cupredoxins contain a single redoxactive Cu ion coordinated by a Cys, a Met, and two His residues. The reduction potentials of cupredoxins range from about 0.15 V to 0.68 V. What does this information reveal about the role of the protein component of the cupredoxins?

The folding and unfolding rate constants for a myoglobin mutant have been determined. The unfolding rate constant ke-u = 3.62 x 10-55 and the folding rate constant ku-p = 255 s1, where Fis the folded protein and U is the unfolded (denatured) protein. For wild-type myoglobin, AG;u = +37.4 kJ/mol. Which myoglobin is more thermodynamically stable, the mutant or the wild-type?

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?