dipeptidases

Dipeptidases are enzymes that catalyze the hydrolysis of dipeptides into their constituent amino acids. A dipeptide is a molecule formed by two amino acids linked by a single peptide bond, and dipeptidases complete the breakdown of such small peptides to allow absorption and reuse of amino acids by cells.

In humans and many other organisms, dipeptidases are found in digestive and cellular contexts. They occur in the small intestine, particularly at the brush border, where they participate in the final steps of dietary protein digestion. They are also present in other tissues such as the kidney and liver, and can be either membrane-bound or cytosolic. Their substrate range includes a variety of dipeptides produced by prior proteolysis, including those generated by endopeptidases and aminopeptidases.

Enzymatic characteristics often include metal dependence; many dipeptidases are metallohydrolases that require divalent metal ions, such as zinc, for catalysis. They belong to different enzyme families and exhibit a degree of substrate specificity, with some showing preference for dipeptides containing particular terminal residues. This specificity influences which dietary dipeptides and endogenous peptides are efficiently metabolized.

Clinically and physiologically, dipeptidase activity contributes to amino acid availability for absorption and to intracellular peptide turnover. Variations in activity can affect peptide-mediated processes and drug metabolism, particularly for peptide-like medications. Dipeptidases are distinct from dipeptidyl peptidases, which remove dipeptides from the N-terminus of longer peptides rather than hydrolyzing just a dipeptide bond.