Burkholderia cepacia中具有解脂作用的胆固醇酯酶的酶学特性

Characterization of cholesterol esterase with lipolytic activity from Burkholderia cepacia

为了更好地应用于工业领域,系统研究Burkholderia cepacia ZWS15胆固醇酯酶(EC 3.1.1.13 cholesterol esterase,CHE)的酶学特性。通过DEAE离子交换从该菌发酵液中获得一种CHE,并探讨其有机溶剂与表面活性剂耐受性,以及底物水解特性。CHE在pH 5.5~9.0保持稳定,最适反应温度为40℃,在70℃温育2 h仍能保留70%以上的酶活,具有显著耐热性;在50%(体积分数)有机溶剂或5%(体积分数)表面活性剂存在下也具有较高酶活。飞行时间质谱鉴定该酶分子质量为37 kDa,其与胆固醇酯酶(源于洋葱伯尔霍尔德菌,Burkholderia cepacia)及脂肪酶(源于假单胞菌属,Pseudomonas sp.)具有较高匹配度。与商品化酶相比,CHE不仅具有胆固醇酯酶活性(对长链胆固醇酯类底物有明显偏好性),还具有解脂功能(可作用于三酰基甘油酯及对硝基苯酯)。该酶的优良性能可为其在食品、诊断、制浆造纸等领域的工业应用提供参考与借鉴。

The characteristics of cholesterol esterase derived from Burkholderia cepacia ZWS15 were systematically studied.The purified cholesterol esterase was obtained by DEAE ion exchange chromatography from culture supernatant and its tolerance to organic solvents and detergents,as well as its hydrolysis characteristics with different substrates were determined.The enzyme was stable at pH 5.5-9.0 and showed optimal activity at 40℃.More than 70%of enzyme activity could be retained after 2 h incubation at 70℃,indicated it was remarkably resistant to heat.Moreover,relatively high enzyme activity could be obtained even in the presence of 50%organic solvents and 5%detergents.Its molecular weight was revealed as 37 kDa by time-of-flight mass spectrometry and high matching degrees were obtained with cholesterol esterase(source of Burkholderia cepacia)and lipase(source of Pseudomonas sp.).Compared to commercially available cholesterol esterase,the enzyme not only preferentially hydrolyzed long-chain fatty acid esters of cholesterol,but also exhibited lipolytic activity towards various triacylglycerides and p-nitrophenyl esters.Overall,this study provides a reference for applying cholesterol esterase in foods,sewage treatment,pulping and papermaking industries.