M20 cytosolic nonspecific dipeptidases including anserinase and serum carnosinase
Peptidase M20 family, CNDP (cytosolic nonspecific dipeptidase) subfamily including anserinase (Xaa-methyl-His dipeptidase, EC 3.4.13.5), 'serum' carnosinase (beta-alanyl-L-histidine dipeptidase; EC 3.4.13.20), and some uncharacterized proteins. Two genes, CN1 and CN2, coding for proteins that degrade carnosine (beta-alanyl-L-histidine) and homocarnosine (gamma-aminobutyric acid-L-histidine), two naturally occurring dipeptides with potential neuroprotective and neurotransmitter functions, have been identified. CN1 encodes for serum carnosinase and has narrow substrate specificity for Xaa-His dipeptides, where Xaa can be beta-alanine (carnosine), N-methyl beta-alanine, alanine, glycine and gamma-aminobutyric acid (homocarnosine). CN2 corresponds to the cytosolic nonspecific dipeptidase (CNDP; EC 3.4.13.18) and is not limited to Xaa-His dipeptides. CNDP requires Mn(2+) for full activity and does not hydrolyze homocarnosine. Anserinase is a dipeptidase that mainly catalyzes the hydrolysis of N-alpha-acetylhistidine.
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