Dipeptidyl peptidase

Dipeptidyl peptidase (DPP) is a type of enzyme that plays a crucial role in the breakdown of proteins. It is involved in the cleavage of dipeptides, which are molecules consisting of two amino acids linked together. DPPs are found in various organisms, including bacteria, plants, and animals, and they are classified into different families based on their structure and function.

Structure and Function

DPPs are typically membrane-bound proteins that are anchored to the cell surface or located within intracellular compartments. They contain a catalytic domain responsible for the enzymatic activity and may also have additional domains that contribute to their specific functions. The catalytic domain of DPPs is characterized by a conserved amino acid sequence motif known as the DPP domain.

The primary function of DPPs is to hydrolyze the peptide bond between two amino acids in a dipeptide molecule. This process involves the addition of a water molecule, resulting in the formation of two separate amino acids. DPPs exhibit substrate specificity, meaning they can only cleave certain dipeptides based on the amino acid sequence and the presence of specific amino acid residues at the cleavage site.

Role in Physiology

DPPs have been implicated in various physiological processes in different organisms. In humans, one of the most well-known DPPs is dipeptidyl peptidase-4 (DPP-4), also known as CD26. DPP-4 is widely expressed in tissues and is involved in the regulation of glucose metabolism. It plays a crucial role in the degradation of incretin hormones, such as glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), which are important regulators of insulin secretion.

The inhibition of DPP-4 activity has been targeted as a therapeutic approach for the treatment of type 2 diabetes. By inhibiting DPP-4, the degradation of incretin hormones is reduced, leading to increased insulin secretion and improved glycemic control. Several DPP-4 inhibitors, such as sitagliptin and saxagliptin, have been developed and are currently used as antidiabetic drugs.

Clinical Significance

Apart from their role in glucose metabolism, DPPs have also been implicated in other physiological and pathological processes. For example, DPP-4 has been shown to play a role in immune regulation, inflammation, and cancer progression. Inhibition of DPP-4 activity has been investigated as a potential therapeutic strategy for autoimmune diseases, such as rheumatoid arthritis, and certain types of cancer.

See Also

• Protease
• Enzyme
• Glucagon-like peptide-1
• Insulin secretion
• Type 2 diabetes