【摘要】 用汾酒大曲根霉糖化酶的纯酶制剂,经十二烷基硫酸钠聚丙烯酰胺凝胶电泳和萄聚糖凝胶过滤法均表明其外观分子量为78,400,经二硫苏糖醇还原和碘乙酸烷化后,凝胶电泳区带并无变化,说明该酶链间无双硫键存在,是只具一条多肽链的蛋白质。聚丙烯酰胺等电聚焦法测定该酶等电点为pH7.8。糖分析表明酶的含糖量为14.55%,相当于约63单糖分子。从氨基酸组成分析表明,该酶含赖氨酸较多。而谷氨酸较少,是一个典型的根霉型糖化酶。更多还原

【Abstract】 The glucoamylase (EC 3.2.1.3.) of Rhizopus sp. from Fen-Jiu koji has been purified and proved to be homogeneous by UV spectra, SDS-polyacrylamide gel electrophoresis and isoelectric focusing. Its molecular weight is 78,400 daltons as estimated by SDS-polyacrylamide gel electrophoreels and gel filtration. The result from one band on SDS-PAGE after reduction and alkylation shows that it has only one peptide chain. The isoelectric point(pⅠ) of the glucoamylase is 7.8 as estimated by isoelectric focusing. However, the glucoamylase is a glycoprotein. It contains 14.55% of total sugar as mannose, corresponding to 63 saccharide units. Therefore, the intrinsic molecular weight would be 67,000 or so. The amino acid composition analysis reveals that the glucoamylase has more quantity lysine residues and less quantity glutamic acid residues than those of Aspergillus type glcooamylase, as other Rhlzopus type glucoamylase do.更多还原