Carboxypeptidase U

Carboxypeptidase U

Carboxypeptidase U structure

Carboxypeptidase U is an enzyme that belongs to the carboxypeptidase family. It plays a crucial role in the breakdown of proteins by cleaving off the terminal amino acid residues from the carboxyl end of peptides. Carboxypeptidase U is primarily found in the pancreas and is involved in the digestion of dietary proteins.

Structure

Carboxypeptidase U is a zinc-dependent metalloenzyme, meaning it requires zinc ions for its catalytic activity. It is composed of a single polypeptide chain that folds into a compact globular structure. The enzyme consists of two distinct domains: the catalytic domain and the regulatory domain. The catalytic domain contains the active site where the peptide cleavage occurs, while the regulatory domain helps in the proper folding and stability of the enzyme.

Function

The main function of carboxypeptidase U is to remove the C-terminal amino acid residues from peptides. It specifically cleaves off basic amino acids, such as lysine and arginine, from the carboxyl end of peptides. This process is essential for the regulation of protein function and metabolism.

Role in Digestion

Carboxypeptidase U is secreted by the pancreas into the small intestine, where it aids in the digestion of dietary proteins. It acts in conjunction with other pancreatic enzymes, such as trypsin and chymotrypsin, to break down proteins into smaller peptides and amino acids. These smaller molecules can then be absorbed by the intestinal lining and utilized by the body for various physiological processes.

Clinical Significance

Mutations or deficiencies in carboxypeptidase U can lead to various disorders. For example, a deficiency in this enzyme has been associated with exocrine pancreatic insufficiency, a condition characterized by the inability to properly digest and absorb nutrients from food. Additionally, carboxypeptidase U has been implicated in certain types of cancer, where its dysregulation can contribute to tumor growth and metastasis.

See Also

• Carboxypeptidase
• Proteolysis
• Pancreatic enzymes