关键词：
内切菊粉酶;外切菊粉酶;酶活性;化学修饰;荧光光谱
摘 要：
选用N-溴代琥珀酰亚胺(NBS)、焦碳酸二乙酯(DEPC)、丁二酮(DIC)、氯氨-T(Ch-T)、碳二亚胺(EDC)、苯甲基磺酰氟(PMSF)和二硫苏糖醇(DTT)等化学修饰剂,通过对Aspergillus ficu-um内切和外切菊粉酶进行修饰,以研究菊粉酶分子中氨基酸侧链基团对酶活性的影响.研究结果表明:内切菊粉酶和外切菊粉酶活性中心的必需氨基酸残基均含有色氨酸和羧基氨基酸,且内切和外切菊粉酶活性中心的色氨酸残基数目分别为1和2;组氨酸可能是酶活性中心的组成基团.荧光光谱法研究表明:内切菊粉酶的色氨酸残基比外切菊粉酶的色氨酸残基所处环境的极性大,对环境的变化更敏感,并且更加暴露,表明这两种酶具有不同的构象,这种构象上的差别可能是导致二者对底物菊粉作用机理不同的原因.
译 名：
Chemical modification and fluorescence spectrum of inulinase from Aspergillus ficuum
作 者：
Chen Xiaoming1,2,3,Chen Hanqing1,2,Wang Jing1,2,Jin Zhengyu1,2,Xu Xueming1,2(1.State Key Laboratory of Food Science and Technology,Jiangnan University,Wuxi,Jiangsu 214122,China;2.School of Food Science and Technology,Jiangnan University,Wuxi,Jiangsu 214122,China;3.School of Life Science and Chemical Engineering,Huaiyin Institute of Technology,Huai′an,Jiangsu 223001,China)
关键词：
endoinulinase;exoinulinase;enzyme activity;chemical modification;fluorescence spectrum
摘 要：
In this study,the effects of amino acid side chain groups in exoinulinase and endoinulinase from Aspergillus ficuum on inulinase activity were studied by chemical modification,using N-bromossuccinimide(NBS),diethyl pyrocarbonate(DEPC),butanedione(DIC),chloramine-T(Ch-T),ethylcarbodiimide(EDC),phenylmethanesulfonyl fluoride(PMSF),and dithiothreitol(DTT) as modification reagents.The results indicated that Tryptophan and carboxyl-containing amino acids residues were involved in active sites of exoinulinse and endoinulinase.The number of Tryptophan residue was estimated to be one for endoinulinase and two for exoinulinase by the method of Zou′s plot.Histidine residue may be essential for active site of inulinases.It was further suggested by fluorescence spectrum analysis that compared to Tryptophan residue in exoinulinase,Tryptophan residue in endoinulinase was located in a more polar environment and was more sensitive to the change of environment,which showed greater exposure,indicating that exoinulinase and endoinulinase had different conformations.
