Aminopeptidase

Aminopeptidases, which are widely distributed in nature, are one of the two major subclasses of the exopeptidases, proteolytic enzymes that remove amino acids from the termini of peptides and proteins (the other being the carboxypeptidases). As the name indicates, the aminopeptidases attack their substrates exclusively from the amino terminal end. Most remove one amino acid at a time, but a small group cleaves two or three residues at a time; these are known as dipeptidyl and tripeptidyl aminopeptidases, respectively. A few enzymes such as acylaminoacyl-peptidase and pyroglutamyl-peptidase remove derivatized amino acids, but generally aminopeptidases require an unmodified or free amino group.