甘露聚糖酶Man23的化学修饰及活性必需基团测定  

The Studies on Chemical Modification and Essential Residues of Mannanase Man23

作　　者：周海燕[1] 董蕾[1] 田梅[2] 饶力群[3] 吴永尧[1] 

机构地区：[1]湖南农业大学生化与发酵工程实验室,湖南长沙410128 [2]湖南农业大学实验室管理中心,湖南长沙410128 [3]湖南农业大学生物科学技术学院,湖南长沙410128

出　　处：《激光生物学报》2007年第6期717-721,共5页Acta Laser Biology Sinica

摘　　要：用化学修饰剂NEM、二甲基溴化锍、EDC、DEPC、TNM、对硝基苯乙二醛、PMSF、TNBS对芽孢杆菌B23产生的甘露聚糖酶M an23进行化学修饰,并测定修饰反应的动力学参数关系。结果显示半胱氨酸、色氨酸(1个)和谷氨酸(或天冬氨酸)残基(2个)是酶活性的必需基团;组氨酸、酪氨酸、精氨酸、丝氨酸和赖氨酸残基均为非必需基团。双向电泳结果显示酶蛋白分子具有一个链内二硫键(Cys90-Cys110)。荧光光谱测定结果显示该酶最大吸收峰为336 nm。底物作用导致酶的发射光谱发生蓝移,说明色氨酸残基位于酶蛋白分子内部的疏水区。The mannanase Man23 produced from Bacillus subtilis B23 was modified by NEM, Dimethyl-（2- hydroxy-5- nitrobenzyl）-sulfonium bromide, EDC, DEPC, TNM, 4-nitrophenylglyoxal, PMSF and TNBS. Man23 could be suppressed by NEM, Dimethyl-sulfonium bromide and EDC and the kinetic parameters were determined. The data indicated that cysteine residues, one tryptophan residue and two carboxyl residues might be the essential groups of Man23. The two-dimenslonal electrophoresis proved that there was a disulfide bond between Cys90 and Cys110 on the single chain. In the presence of ligands-binding,the λmax emission fluorescence spectrum of the Man23 changed from 336 nm ＇to 330 nm. It appeared that tryptophan residues were involved in a hydrophobic micro-environment of mannanase Man23 molecule.

关 键 词：甘露聚糖酶 化学修饰 必需基团 

分 类 号：Q78[生物学—分子生物学]