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 pK_a for water, which leads to formation of a zinc bound hydroxide ion. E) an altered K_M value.

Question

Quizplus · Accepted Answer

The binding of a water molecule to the zinc ion in the active site of an enzyme typically results in a decrease in the pKa of the water molecule. This makes the water more acidic, facilitating its ionization to form a hydroxide ion that is bound to the zinc. This hydroxide ion can then act as a potent nucleophile in catalytic processes.

Binding of a Water Molecule to the Zinc Ion Induces