dipeptidase

Dipeptidase is a class of proteolytic enzymes that catalyze the hydrolysis of dipeptides into two free amino acids. In biochemical terms, the reaction is dipeptide plus water yielding two amino acids. Dipeptidases are exopeptidases that act on dipeptides rather than longer polypeptides, although dipeptides can be generated during digestion or peptide turnover and then further broken down by these enzymes.

Dipeptidases show diverse catalytic strategies; some are metallopeptidases requiring a metal such as zinc, others belong to serine or cysteine protease families. Substrate specificity can vary, with some dipeptidases displaying broad activity toward many dipeptides and others preferring dipeptides with particular terminal residues.

Distribution and roles vary across organisms. In animals, dipeptidases are found in digestive tissues such as the intestinal brush border and in cellular compartments where peptide turnover occurs. In plants and microorganisms, they participate in nitrogen metabolism and peptide catabolism. Their activity complements other peptidases by completing the breakdown of small peptide fragments into absorbable amino acids, contributing to amino acid supply for protein synthesis and energy.

Dipeptidases should not be confused with dipeptidyl peptidases, such as DPP-4, which are a different group of enzymes that remove dipeptides from the N-terminus of longer polypeptides. Both kinds of enzymes interact with dipeptides, but they act on different substrates and play distinct physiological roles.