丝孢酵母脂肪酶的酶学性质和化学修饰

Properties and Chemical Modification of Lipase from Trichosporon sp.

摘要:

实验室筛选到的一株丝孢酵母Trichosporon sp. 脂肪酶经过硫酸铵沉淀和一系列的层析步骤分离纯化到电泳纯。对纯酶的酶学性质研究表明，此酶的分子量为28 kD，pI 为pH 8.7，最适作用温度40℃，最适作用pH为8.0。随后利用不同的化学修饰剂对酶蛋白进行修饰，通过酶催化活力的改变对位于酶活性位的氨基酸残基进行分析，结果表明酶活性位可能含有组氨酸、丝氨酸和谷氨酸（或天冬氨酸）。最后，对此酶的氨基酸成分进行了分析，结果表明，此酶分子中天冬氨酸、丝氨酸、谷氨酸、甘氨酸、丙氨酸含量高，两种碱性氨基酸精氨酸、赖氨酸及组氨酸的含量也比较高，而脯氨酸、色氨酸的含量相对较低。

Abstract:

A lipase from Trichosporon sp. screened by my lab was purified to homogeneity by ammonia sulphate precipitation and a series of chromatographic steps. The properties of purified Trichosporon sp. Lipase were investigated. Its Molecular weight and isoelectric point were 28kD and pH 8.7, the optimum temperature and pH were 40℃ and pH 8.0. Several chemical modification agents were applied to investigate amino acid residues in active site of this enzyme and the results demonstrated that histidine, serine, glutamic acid/asparaginic acid are located in the active site. The composition of amino acid of the enzyme was also analyzed，which indicated that the contents of asparaginic acid, serine, glutamic acid, glycin, alanine are the most, lysine, histidine also have high contents and there are a few praline, tryptophan.