【摘要】 用Ｂａｃｉｌｌｕｓｓｐｈａｅｒｉｃｕｓ６３菌为材料，经ＤＮＡ－Ｓｅｐｈａｒｏｓｅ和ＣｉｂａｃｒｏｎＢｌｕｅＦ３ＧＡ－Ｓｅｐｈａｒｏｓｅ两步亲和层析，将Ｂｓｐ６３Ⅰ纯化到均一程度。酶比活力达６１４００Ｕ／ｍｇ蛋白。用凝胶过滤法测得该酶分子量为１１３８００。该酶样品在ＳＤＳ－ＰＡＧＥ中呈现为一条蛋白带，并测得其亚基分子量为５６８００。用ＤＮＳ－Ｃｌ法测得该酶Ｎ－末端氨基酸为丙氨酸。上述结果表明该酶分子是由两个相同亚基组成。更多还原

【Abstract】 Restriction endonuclease Bsp 63I from Bacillus sphaericus 63 has been isolate and purified by affinity chromatography on DNA-Sepharose and Cibacron Blue F3GA-Sepharose. The purified enzyme was found to be homogeneous as judged by polyacrylamide gel disc electrophoresis. The specific activity of the enzyme is about 61400 units per mg protein. The enzyme hasa molecular weight of 113800 daltons by Sephadex G-200 gel filtration, that of the enzyme subunit is 56800 daltons as assayed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. On electrophoresis the subunit migrated as a single band. The N-terminal amion acid of the enzyme is alanine as assayed by dansyl chloride. These results show that Bsp 63Ⅰconsists of two similar subunits.更多还原