RT Journal Article SR Electronic(1) A1 Basten, Daniëlle E. J. W A1 Visser, Jaap A1 Schaap, Peter JYR 2001 T1 Lysine aminopeptidase of Aspergillus nigerThe EMBL accession number for the sequence reported in this paper is AJ292570. JF Microbiology, VO 147 IS 8 SP 2045 OP 2050 DO https://doi.org/10.1099/00221287-147-8-2045 PB Microbiology Society, SN 1465-2080, AB Conserved regions within the M1 family of metallo-aminopeptidases have been used to clone a zinc aminopeptidase from the industrially used fungus Aspergillus niger. The derived amino acid sequence of ApsA is highly similar to two yeast zinc aminopeptidases, LAPI and AAPI (53·3 and 50·9% overall similarity, respectively), two members of the M1 family of metallo-aminopeptidases. The encoding gene was successfully overexpressed in A. niger and the overexpressed product was purified and characterized. Aminopeptidase A was found to be active towards a number of amino acid p-nitroanilide (pNA) substrates, viz. K-pNA, R-pNA, L-pNA, M-pNA, A-pNA and F-pNA. The most preferred N-terminal amino acid is lysine and not leucine, arginine or alanine, the N-terminal amino acids preferred by the yeast homologues. The K m and K cat for K-pNA and L-pNA were 0·17 mM and 0·49 μkat mg−1, and 0·16 mM and 0·31 μkat mg−1, respectively. The pH optimum of the enzyme is between 7·5 and 8, whereas the enzyme is stable between pH 5 and 8. The enzyme is inhibited by the metal chelators EGTA, EDTA and 1,10-phenanthrolin. Bestatin was also able to inhibit the activity., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-147-8-2045