蜡质芽孢杆菌超氧化物歧化酶的理化性质研究

CHARACTERIZATION OF SUPEROXIDE DISMUTASE FROM BACILLUS CEREUS

本文对从蜡质芽孢杆菌发酵菌体中纯化的Ｆｅ－ＳＯＤ进行了理化性质研究，测定结果表明：在２７℃，ｐＨ６８，光照强度为４０００Ｌｕｘ条件下，光照２０分钟为酶活性测定的最佳条件；经ＳＤＳ－聚丙烯酰胺凝胶电泳分析得其亚基分子量为１７，７８３道尔顿；等电聚焦电泳表明：Ｆｅ－ＳＯＤ的等电点（ＰＩ）大约为６５左右；经ＤＮＳ法分析Ｎ－末端氨基酸为谷氨酸（Ｇｌｕ）；其氨基酸的组成中酸性氨基酸的含量大于碱性氨基酸的含量，表明此酶为酸性蛋白。

The characterization of the purified enzyme was studies, enzyme activity showed the optimum activity under the conditions of 27℃, 4000lux, illuminating for 20min and pH6.8. The subunit molecular weight of the enzyme was estimated at 17,783 daltons on SDS-polyacrylamide gels. The isoelectric point is 6.5 as determined by isoelectric focusing. The amino terminal residue was glutamic acid (Glu) by using Dansyl-method. The amino acid composition of Fe-SOD purified from Bacillus cereus appeared to contain more acid amino acids than alkaline amino acids. The result showed the purified enzyme was acidic protein.