【摘要】 产气气杆菌（Aerobacter aerogenes）10016的茁霉多糖酶（pullulanase E.C.3.2.1.41）用 Sephadex G100凝胶过滤、聚丙烯酰胺垂直板型凝胶电泳进行纯化,得到了聚丙烯酰胺凝胶电泳均一的纯酶。纯酶作用的最适温度为50℃,最适 pH 为5.3—5.8,耐热性较差,50℃4小时后仅存活力10%。纯酶在 pH4.3—8.6稳定。酶作用于糯米淀粉的米氏常数 K_m 为2.0×10^-2克/毫升。用聚丙烯酰胺薄层凝胶等电聚焦测定酶的等电点 pI 为3.8,用 SDS 凝胶电泳测定酶的分子量为51,000—52,000;此酶是一种糖蛋白;含糖总量为6.5—7.0%;纯酶能专一性的水解茁霉多糖、糯米淀粉,也能分解糊精,而不作用于糖原、纤维二糖以及环状糊精。更多还原

【Abstract】 The pullulanase （E.C.3.2.1.41） ofA.aerogenes was purified by gel filtrationon Sephadex G-100 column and prepara-tive polyacylamide slab gel electropho-resis.The purified enzyme showed asingle band on Disc electrophoresis.Thetemperature optimum for enzyme activitywas 50℃ and the pH optimum was 5.3—5.8.The thermostability seemed low,asonly 10% of the original enzyme activitywas remained after incubation at 50℃ for4 hours.It was stable in the pH range4.3—8.5.The Michaelis constant （K_m）for glutinous rice starch was 2.0×10^-2g/ml.The isoelectric point is 3.8 as deter-mined by isoelectric focusing on polyac-rylamide gel.Its Molecular weight is51000—52000 as estimated by SDS po-lyacrylamide gel electrophoresis.It actson glutinous rice starch,pullulan anddextrin,but not on glycogen,dextran,cellobiose and cyclodextrins.This enzymeis a glycoprotein,containing 6.5—7.0%total sugar as mannose.更多还原