The active site of a certain enzyme contains a serine residue.When the enzyme is incubated for a short time with its substrate,a form of the enzyme in which the active site serine is acetylated can be isolated and purified.In the native protein the serine is never found to be acetylated.This information supports ________.
A)a covalent catalysis mode
B)intermediate state stabilization effects
C)the acid-base catalysis mode
D)a polar group catalytic mechanism

Question

Quizplus · Accepted Answer

The fact that the active site serine residue is acetylated in a short time suggests that it played a role in the catalytic mechanism of the enzyme. This supports covalent catalysis mode, where a nucleophilic group such as serine forms a covalent bond with the substrate during the catalytic reaction.

The Active Site of a Certain Enzyme Contains a Serine