摘要
经硫酸铵分级分离 ,DEAE- cellulose5 2 ,CM- cellulose5 2和 Sephacryl S10 0 HR凝胶过滤层析方法从熊猫豆黄化苗中获得了一种β- D -半乳糖苷酶 ,活性收率为 8.0 % ,纯化倍数为 2 4 5 .经PAGE显示单一蛋白着色带 ,用 IEF- PAGE测定其 PI为 4 .1.SDS- PAGE显示 2条蛋白着色带 ,其相应分子量分别为 4 0 k D和 2 9k D.Sephadex G2 0 0层析法测得表观分子量为 6 8k D.以 ONPG和PNPG为底物测得该酶的表观 Km 分别为 3.0 2 mmol/ L和 0 .33mmol/ L.最适 p H为 4 .2 ,最适温度为 5 2℃ .以乳糖为底物测得表观 Km 为 4 3mmol/ L.Hg CI2 ,DTNB,NEMI,半乳糖和乳糖对酶表现出不同的抑制作用 .
β-D- galactosidase from panda bean was purified by means of ammonium sulphate fractionation and chromatographies on DEAE cellulose 52,CM cellulose 52 and Sephacryl S 100HR. The enzyme displayed the activity against o nitrophenyl β D galactopyranoside(ONPG) with Km 3.02 mmol/L,p nitrophenyl β D galactopyranoside(PNPG) with K m 0.33 mmol/L, and Lactose with 43.0 mmol/L.Enzyme activity was higher within pH range of 3.0～3.6 with an optimum at pH 4.2 and 52 ℃.The molecular weight of 68 kD was determined by molecular sieve chromatography on Sephadex G 200 and SDS PAGE.The enzyme appeared to be a dimer of two different subunits with 40 kD and 29 kD. It was inhibited by Lactose(K i 162 mmol/L),Galactose,HgCl 2,DTNB and NEMI.
出处
《兰州大学学报（自然科学版）》
CAS
CSCD
北大核心
2001年第5期88-93,共6页
Journal of Lanzhou University(Natural Sciences)
基金
国家自然科学基金 (2 95 7310 7)资助项目
