Dipeptidyl carboxypeptidase

Structure of Dipeptidyl Carboxypeptidase

Dipeptidyl carboxypeptidase is an enzyme that plays a crucial role in the metabolism of peptides. It is also known as dipeptidyl peptidase IV (DPP-IV) or CD26. This enzyme is found in various tissues and is involved in the breakdown of peptides by cleaving dipeptides from the N-terminus of proteins or peptides.

Structure and Function

Dipeptidyl carboxypeptidase is a type II transmembrane glycoprotein that belongs to the prolyl oligopeptidase family. It consists of a large extracellular domain, a single transmembrane helix, and a short cytoplasmic tail. The extracellular domain contains the active site responsible for the enzymatic activity.

The main function of dipeptidyl carboxypeptidase is to cleave dipeptides from the N-terminus of peptides or proteins. This cleavage occurs specifically after a proline or alanine residue. By removing dipeptides, this enzyme regulates the levels of various bioactive peptides, including incretins, neuropeptides, and chemokines.

Role in Physiology

Dipeptidyl carboxypeptidase is widely expressed in various tissues, including the liver, kidney, intestine, and immune cells. It is involved in numerous physiological processes, including glucose homeostasis, immune regulation, and inflammation.

In glucose homeostasis, dipeptidyl carboxypeptidase plays a crucial role in the regulation of blood sugar levels. It inactivates incretin hormones, such as glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), by cleaving off their N-terminal dipeptides. This inactivation prevents excessive insulin secretion and helps maintain glucose balance.

Dipeptidyl carboxypeptidase also plays a role in immune regulation. It is involved in the activation and migration of T cells, as well as the modulation of cytokine production. Additionally, it has been implicated in the pathogenesis of autoimmune diseases, such as rheumatoid arthritis and systemic lupus erythematosus.

Clinical Significance

Due to its involvement in glucose homeostasis, dipeptidyl carboxypeptidase has become an important target for the treatment of type 2 diabetes mellitus. Inhibitors of this enzyme, known as DPP-IV inhibitors, have been developed as a new class of antidiabetic drugs. These inhibitors prolong the action of incretin hormones, leading to increased insulin secretion and improved glycemic control.

Furthermore, dipeptidyl carboxypeptidase has been studied as a potential therapeutic target for various other conditions, including cancer, inflammatory diseases, and viral infections. Its role in immune regulation and inflammation makes it an attractive target for the development of novel therapies.