Lysine aminopeptidase of Aspergillus niger

D.E.J.W. Basten, J. Visser, P.J. Schaap

Research output: Contribution to journalArticleAcademicpeer-review

26 Citations (Scopus)

Abstract

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␘verall 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 Km and Kcat 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.
Original languageEnglish
Pages (from-to)2045-2050
JournalMicrobiology
Volume147
Publication statusPublished - 2001

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