exopeptidase

{{Short description|Class of enzymes}}

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An exopeptidase is any peptidase that catalyzes the cleavage of the terminal (or the penultimate) peptide bond; the process releases a single amino acid, dipeptide or a tripeptide from the peptide chain.{{Cite book |last=Škárka |first=Bohumil |title=Biochémia |publisher=Alfa |year=1992 |isbn=80-05-01076-1 |location=Bratislava |pages=360, 688 |language=SK}} Depending on whether the amino acid is released from the amino or the carboxy terminal (N-terminus or C-terminus), an exopeptidase is further classified as an aminopeptidase or a carboxypeptidase, respectively. Thus, an aminopeptidase, an enzyme in the brush border of the small intestine, will cleave a single amino acid from the amino terminal, whereas carboxypeptidase, which is a digestive enzyme present in pancreatic juice, will cleave a single amino acid from the carboxylic end of the peptide.

Some examples of exopeptidases include:

• Carboxypeptidase A - cleaves C-terminal Phe, Tyr, Trp, or Leu
• Carboxypeptidase B - cleaves C-terminal Lys or Arg
• Aminopeptidase - cleaves any N-terminal amino acid
• Prolinase - cleaves N-terminal Pro from dipeptides{{Cite web |title=Definition of prolinase {{!}} Dictionary.com |url=https://www.dictionary.com/browse/prolinase |access-date=2022-04-09 |website=www.dictionary.com |language=en |archive-date=2022-04-09 |archive-url=https://web.archive.org/web/20220409153212/https://www.dictionary.com/browse/prolinase |url-status=dead }}
• Prolidase - cleaves C-terminal Pro from dipeptides{{Cite journal |last=Namiduru |first=E. S. |date=2016 |title=Prolidase |url=https://pubmed.ncbi.nlm.nih.gov/27546702/ |journal=Bratislavske Lekarske Listy |volume=117 |issue=8 |pages=480–485 |doi=10.4149/bll_2016_093 |issn=0006-9248 |pmid=27546702|doi-access=free }}