The active site of lysozyme contains two amino acid residues essential for catalysis: Glu35 and Asp52. The pKa values of the carboxyl side chains of these residues are 6.3 and 4.5, respectively. What is the pH optimum of lysozyme based on the plot of pH versus rate, below? What is the ionization state (protonated or deprotonated) of each residue at this pH optimum? Which of these residues, either Glu-35 or Asp-52 act as a base in the catalytic mechanism, consistent with these data.