海枣曲霉β-葡萄糖苷酶的催化性质

CATALYTIC PROPERTIES OF β-GLUCOSIDASE FROM ASPERGILLUS PHOENICIS

本文研究了海枣曲霉(Aspergillus phoenicis)β-葡萄糖苷酶的底物特异性以及不同化学试剂对酶活力的影响。该酶水解对-硝基酚基-β-葡萄糖苷、纤维二糖和水杨素的相对活力分别为100、180和67.3。水解对-硝基酚基β-葡萄糖苷和纤维二糖的 K_m 值分别为0.97mmol/L和1.8mmol/L,V_(max)分别为576μmol·min^(-1)·mg^(-1)和595μmol·min^(-1)·mg^(-1)。Ag^+、D^-葡萄糖和纤维二糖对酶活力有强烈的抑制作用。Lineweaver-Burk 作图法及 Dixon 作图法表明D-葡萄糖对该酶显示竞争性抑制作用,其 K_i 值分别为3.0mmol/L 和3.4mmol/L。

Substrate specificities and inhibitors of the purified β-glucosidase from Aspergillusphoenicis were investigated.The relative activity of β-glucosidase toward p-nitrophenylβ-glucoside,cellubiose and sahcin were 100,180 and 67.3.The K_m values for p-nitrophenylβ-glucoside and ceUubiose were 0.97mmol/L and 1.8mmol/L,respectively.The V_(max)values were 576μmol·min^(-1)·mg^(-1) and 595μmol·min^(-1)·mg_(-1),respectively.The enzymeactivity was inhibited by Ag^+,D-glucose,cellubiose.The K_i for D-glucose was 3.0mmol/L(3.4 mmol/L)as determined by Leneweaver-Burk plot(Dixon plot).The enzymewas strongly inhibited by D-glucono-δ-lactone.