Binding of a water molecule to the zinc ion induces:
A) a hydronium ion to form.
B) a large conformation change in the binding site.
C) ionization of a his residue, which functions as a strong nucleophile.
D) a lowered pKa for water, which leads to the formation of a zinc-bound hydroxide ion.
E) an altered KM value.

Question

Quizplus · Accepted Answer

Binding of a water molecule to the zinc ion lowers the pKa of water, which leads to the formation of a zinc-bound hydroxide ion. This is due to the fact that the positively charged zinc ion polarizes the water molecule, making it more acidic and promoting the release of a proton to form a hydroxide ion.

Binding of a Water Molecule to the Zinc Ion Induces