Problem 22
For a protein with a surface-exposed aspartic acid, at what \(\mathrm{pH}\) will this residue be neutral in \(75 \%\) of the protein molecules? (Assume that the \(\mathrm{p} K_{\mathrm{a}}\) is \(4.0\).)
Problem 23
A histidine is involved in an interaction with a glutamic acid that stabilizes the charged form of the histidine, such that the value of \(A G^{\circ}\) for deprotonation is 15 \(\mathrm{kJ} \cdot \mathrm{mol}^{-1}\) at \(\mathrm{pH} 7.0\) and \(293 \mathrm{~K}\) (calculated using the biochemical standard state). What is the \(\mathrm{p} K_{a}\) of this histidine?
Problem 27
In the hydrophobic core of a folded protein, there are three alanine and five pherrylalanine residues that are buried, and do not interact with water. Assume: \- In solution, waters can take on seven energetically equal states. \- Two waters are ordered around each alanine in the unfolded state. \- Six waters are ordered around each phernylalanine in the unfolded state. \- In the unfolded state, waters are ordered around alanine or pherylalanine residues and can take on only two energetically equal states. What is the difference in the entropy of the water due to the burying of these residues as this protein folds?
Problem 29
How do hydrophobic interactions provide favorable entropy for protein folding?
