Karboxypeptidases

Karboxypeptidases are a class of enzymes that catalyze the hydrolysis of the peptide bond at the carboxyl terminal end of a peptide or protein. This means they cleave amino acids one by one from the C-terminus. They are a type of protease, specifically exopeptidases, as they act from the end of a polypeptide chain. Karboxypeptidases are crucial in various biological processes, including protein digestion and turnover, as well as in the processing of hormones and neuropeptides.

There are different types of karboxypeptidases, broadly classified based on their catalytic mechanism. These include serine karboxypeptidases, zinc-dependent karboxypeptidases, and cysteine karboxypeptidases. Zinc-dependent karboxypeptidases, such as karboxypeptidase A and karboxypeptidase B, are particularly well-studied and play significant roles in the digestive system. Karboxypeptidase A typically cleaves aromatic and aliphatic amino acids, while karboxypeptidase B specifically removes basic amino acids like arginine and lysine.

In the digestive tract, karboxypeptidases contribute to the complete breakdown of dietary proteins into absorbable amino acids and small peptides. Beyond digestion, these enzymes are involved in the maturation of various biologically active peptides and proteins by removing signal sequences or processing precursors. Their activity is tightly regulated to ensure proper protein metabolism and function. Deficiencies or dysregulation of karboxypeptidase activity can lead to various health issues, highlighting their importance in maintaining physiological balance.