A novel lipolytic enzyme-encoding gene, lipO745, from Aspergillus oryzae RIB40 was cloned and expressed in Pichia pastoris. Purified recombinant LipO745 (rLipO745) had a molecular mass of approximately 60 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. rLipO745 exhibited maximum activity at 40 °C and pH 7.0 and was stable at temperatures ≤ 40 °C. The substrate specificity of purified rLipO745 was analyzed using α-naphthyl esters as artificial substrates and various triacylglycerol and sterol esters as natural substrates. From among a panel of α-naphthyl esters (C2–C16), α-naphthyl butyrate (C4), with an activity of 269 ± 3.3 units/mg protein, was the optimal substrate for hydrolysis by the purified recombinant protein. The K_m and k_cat values of rLiO745 for the C4 substrate were 0.073 ± 0.0012 mM and 608 ± 108 s⁻¹, respectively. The purified recombinant enzyme had considerable hydrolytic activity toward tributyrin, tripalmitin, and triolein, indicating lipase activity, and toward cholesteryl acetate, butyrate, palmitate, and oleate, indicating sterol esterase activity. Transesterification activities between tributyrin and cholesterol or between tributyrin and campesterol were also determined.

从米曲霉RIB40克隆了一个新的脂解酶编码基因lipO745，并在巴斯德毕赤酵母中表达。在十二烷基硫酸钠-聚丙烯酰胺凝胶电泳上，纯化的重组LipO745（rLipO745）的分子量约为60 kDa。rLipO745在40°C和pH 7.0下表现出最大活性，并且在≤40°C的温度下稳定。以α-萘基酯为人工底物，各种三酰基甘油和固醇酯为天然底物，分析了纯化的rLipO745的底物特异性。在一组α-萘基酯（C2-C16）中，α-萘基丁酸酯（C4）的活性为269±3.3单位/ mg蛋白，是纯化的重组蛋白水解的最佳底物。该ķC4基板的rLiO745的_m和k _cat值分别为0.073±0.0012 mM和608±108 s ^-1。纯化的重组酶对三丁酸甘油三酯，三棕榈精和三油精具有相当大的水解活性，表明具有脂肪酶活性，对乙酸胆固醇，丁酸酯，棕榈酸酯和油酸酯具有水解活性，表明甾醇酯酶活性。还确定了三丁酸甘油酯和胆固醇之间或三丁酸甘油酯和菜油甾醇之间的酯交换活性。