Predict how the following environmental changes will affect the pKa of a H residue in a protein:
a) a D residue in the same protein is brought into close proximity
b) the H side chain shifts from the outside of the protein to a nonpolar site inside
c) an R residue in the same protein, that was close, moves away.
In each case, will the pKa go up, down, or remain the same? Explain