Zinc, an essential trace element for most organisms, is present ...

[Hawke]

Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as a(n)
A) competitive inhibitor of the enzyme.
B) noncompetitive inhibitor of the enzyme.
C) allosteric activator of the enzyme.
D) cofactor necessary for enzyme activity.
E) coenzyme derived from a vitamin.

[coco]

The answer is D. I remember this question on my exam.

[Hawke]

Thanks It was right.