Leucine aminopeptidase (LAP) is an exopeptidase hydrolyzing the peptide bond adjacent to a free amino group. LAP is extensively used in the sequence analysis of proteins and peptides. .The enzyme liberates amino acids from the N-terminal end of a number of proteins and polypeptides. It is called leucine aminopeptidase because it reacts most rapidly with leucine compounds. Many aliphatic amides are also hydrolyzed as well as thiolesters.LAP consists of four subunits each having one atom of zinc.

PEPS levels did not differ from controls in any. This experience permitted exclusion mapping of PEPS to 4p11-4q13; combined with previously reported data, the assignment becomes 4p11-4q12.