cl00603

DmpA/OAT superfamily; composed of L-aminopeptidase D-amidase/D-esterase (DmpA), ornithine acetyltransferase (OAT) and similar proteins. DmpA is an aminopeptidase that releases N-terminal D and L amino acids from peptide substrates. This group represents one of the rare aminopeptidases that are not metalloenzymes. DmpA shows similarity in catalytic mechanism to N-terminal nucleophile (Ntn) hydrolases, which are enzymes that catalyze the cleavage of amide bonds through the nucleophilic attack of the side chain of an N-terminal serine, threonine, or cysteine. OAT catalyzes the first and fifth steps in arginine biosynthesis, coupling acetylation of glutamate with deacetylation of N-acetylornithine, which allows recycling of the acetyl group in the arginine biosynthetic pathway. The superfamily also contains an enzyme, endo-type 6-aminohexanoate-oligomer hydrolase, that have been shown to be involved in nylon degradation. Proteins in this superfamily undergo autocatalytic cleavage of an inactive precursor at the site immediately upstream to the catalytic nucleophile.