Question

6) Choose one. How does Diethyl pyrocarbonate (DEPC) affect chymotrypsin?

a) It stimulates chymotrypsin catalytic activity

b) It inhibits chymotrypsin catalytic activity

c) Chymotrypsin catalytic activity is unaffected

7) Select all that apply. Mercury (II) binds to both of chymotrypsin’s histidines, causing inhibition followed by irreversible denaturation/ aggregation. Adding Hg2+ to the enzyme has what effect?

a) The Hg2+ can change the chemical environment enough to disrupt protein folding.

b) The tight binding of Hg2+ to the seleno-cysteine and cysteine-thiol results in greater substrate affinity thus lowering the Km for its substrate.

c) The Hg2+ acted as a catalytic acid in chymotrypsin, thus increasing the reaction rate.

d) In the presence of Imidazole, the Chymotrypsin was not as effected by the Hg2+ because imidazole had a higher binding affinity.

e) In Chymotrypsin, Hg2+ most likely interacts with the cysteine-thiol residues removes the amino acid residue’s ability to act as a catalytic acid.

8) Choose one. Mercury (II) binds to both of chymotrypsin’s histidines, causing inhibition followed by irreversible denaturation/ aggregation. Which of these does Hg²⁺ NOT bind to:

a) DEPC

b) Selenocysteine

c) Histidine

d)Cysteine