9. Studies at different pH values show that an enzyme has two catalytically important
residues whose pK values are ~4 and ~10. Other experiments indicate that a Glu
and a Lys are essential for activity. Match the amino acids to their pK values and
explain whether they are likely to as acid or base catalysis.
A. pK ~4 is Glu and pK ~10 is Lys. Glu acts as a base and Lys acts as an acid.
B. pK ~4 is Glu and pK ~10 is Lys. Glu acts as an acid and Lys acts as a base.
C. pK ~4 is Lys and pK ~10 is Glu. Glu acts as an acid and Lys acts as a base.
D. pK ~4 is Lys and pK ~10 is Glu. Glu acts as a base and Lys acts as an acid.
E. pK ~4 is Glu and pK ~10 is Lys. Glu acts as an acid and Lys acts as an acid.