The reaction mechanism for glyceraldehyde-3-phosphate dehydrogenase involves ____ attack by a cysteine -SH group on the ____ carbon of the substrate to form a hemithioacetal.

Question

Quizplus · Accepted Answer

Glyceraldehyde-3-phosphate dehydrogenase is a member of a group of enzymes that catalyze the conversion of aldehydes to carboxylic acids. The reaction mechanism of this enzyme involves the nucleophilic attack of a cysteine-SH group on the carbonyl carbon of the substrate to form a hemithioacetal intermediate. This is followed by the transfer of a hydride ion from the substrate to the enzyme-bound NAD+ to form NADH and a thioester intermediate. The thioester intermediate then undergoes hydrolysis to release the carboxylic acid product and regenerate the enzyme-SH group. Thus, the correct answer is D.

The Reaction Mechanism for Glyceraldehyde-3-Phosphate Dehydrogenase Involves ____ Attack by a Cysteine