Abstract: An aminopeptidase was purified and characterized from crude extracellular protease extract from wheat bran koji of Mucor through ammonium sulfate precipitation, ion exchange chromatography, hydrophobic chromatography, gel filtration chromatography and ultra-filtration. The purified aminopeptidase was identified as leucine aminopeptidase, which was very active in hydrolyzing N-terminal leucine of peptides. Its maximum activity was observed at pH 6.5 and 40 ℃. In addition, the leucine aminopeptidase was stable in the pH range of 5.0－8.0 and at temperatures below 40 ℃. However, it could be completely inhibited by the metal protease inhibitor EDTA, indicating that it belongs to the metal protease family. Ca2+ had an activating effect on it, while Zn2+, Cu2+ and Mn2+ were very active in inhibiting it. The enzyme was effective in removing bitter taste from soybean ploypeptides and basic elimination of bitter taste was achieved after 4 h of treatment with it.

Key words: Mucor, leucine aminopeptidase, purification, properties, debittering