5.1.4 Aminopeptidases and Arylamidases
These enzyme assays have been linked here as they have some common applications in
diagnostic enzymology.
Alanine aminopeptidase (AAP) and leucine arylamidase (LAAP) hydrolyse peptides at the N-terminal amino acid and some amino acid amides; the enzymes respectively hydrolyse leucyl- and alanyl-4-nitroanilide substrates. They occur in microsomes and are also membrane bound, and they have been used in studies of both hepatotoxicity and nephrotoxicity. These two enzymes should not be confused with cytosolic leucine aminopeptidase (LAP): this enzyme is an aminopeptidase which hydrolyses N-amino acid residues of proteins, in particular those with an N-terminal 1-leucine where 1-leucyl-β-napthylamide is commonly used as substrate.