【摘要】 产碱菌(Alcaligenes sp.)537.1除去菌体的培养液经硫酸铵沉淀及 DEAE-纤维素离子交换柱层析,得到了凝胶电泳均一的麦芽四糖淀粉酶。纯化了141倍,酶活力回收40.1%,比活力达3308U/mg。用浓度梯度 PAGE 和 SDS-PAGE 测定酶分子量分别为68000和66000,不具亚基。用 PAG-IEF 测定等电点为4.45。酶反应最适 pH 和温度分别为7.0和60℃。在 pH7—10范围内稳定,该酶半衰期为37℃ 12小时,50℃ 1小时和62℃ 6分钟。麦芽四糖淀粉酶是糖蛋白,含有4%左右的糖,含有27.10%酸性氨基酸、11.08%碱性氨基酸和1.82%色氨酸。更多还原

【Abstract】 A mahotetraose-forming amylase from the culture supernatant of Alcaligenes sp.537.1 was purified to PAGE homogenous by ammonium sulfate precipitation followedby dialysis and DEAE-cellulose column chromatography with 141-fold purification and40% recovery.The Mr estimated with concentration gradient PAGE and SDS-PAGE were 68000and 66000.The pI was 4.5 determined with PAG-IEF.The optimum conditions foractivity were pH 7.0,temperature 60℃,stable in the range pH 7.0—10.0.The half lifeof enzyme was 12h,1h and 6 min at 37℃,50℃ and 62C℃,respectively.The enzyme was a glycoprotein with sugar content of about 4%.Analyses of aminoacids composition showed that the enzyme contained about 27.10% acidic amino acids,11.08% basic amino acids and 1.82% Tryptophan.更多还原