诺卡氏菌株胞外β-淀粉酶的分离和鉴定

The Separation and Characterization of Amylase Produced by Nocardia sp.82

诺卡氏菌株（Nocaridasp．）82除去菌体的发酵液经硫酸镀沉淀、DEAE-纤维素离子交换层析、SephadexG－200凝胶过滤，得到高纯度的β-淀粉酶。用SDS－PAGE测定酶蛋白分子量为53000，不具亚基；酶反应最适pH和温度分别为7．0和60℃，有较高的热稳定性；Fe2十和Zn2+对酶活力有促进作用，而Hg2+对酶活力有抑制作用。

A thermostableβ-amylase from the culture supernatant of Nocardia sp.82 was purified to PAGE homogenous by ammonium sulfate precipitation DEAE-cellulose column chromatography and sephadex G-200 filtration with 33.02 fold purification and 37.2% recovery. The molecular weight estimated with SDS-PAGE was 53000. The optimum conditions for activity were pH7.0, temperature 60℃, and it remained 40% activi ty at 100℃ (30min). Theβ-amylase was activated by Fe2+、 Zn2+ and it was inhibied by Hg2+.