Carboxypeptidase

Humans, animals, bacteria and plants contain several types of carboxypeptidases that have diverse functions ranging from catabolism to protein maturation.

They also regulate biological processes, such as the biosynthesis of neuroendocrine peptides such as insulin requires a carboxypeptidase.

Carboxypeptidases also function in blood clotting, growth factor production, wound healing, reproduction, and many other processes.

Glu 270 has a dual role in this mechanism as it acts as a base to allow for the attack at the amide carbonyl group during nucleophilic addition.

The interaction between the carbonyl group and the neighbouring arginine, Arg 217, also stabilizes the negatively charged intermediates.

The zinc-bound hydroxide interacts with the amide with the electrostatic stabilization of the transition state provided by the Zn2+ ion and the neighbouring arginine.