Bacillus sp.CBB272脱枝酶的酶学性质

Biochemical Properties of Debranching Enzyme from Bacillus sp.CBB272

DOI：10.3969/j.issn.1673-1689.2011.01.023

中文关键词: 脱枝酶 纯化 酶学性质

英文关键词: debranching enzyme purification biochemical properties

基金项目:国家863计划项目(2006AA020204);国家自然科学基金国际合作项目(2008GR0918)

摘要点击次数: 173

全文下载次数: 586

中文摘要:

脱枝酶是淀粉加工过程中水解其1,6-糖苷键的水解酶,为淀粉彻底糖化所必需。作者从高温菌Bacillus sp.CBB272的培养液中,经过盐析、凝胶过滤层析、弱阴离子交换层析以及强阴离子交换层析联用的方法,纯化出一种新型脱枝酶。该酶在SDS-PAGE上的相对分子质量约为70 000,最适作用温度为70℃,最适作用pH为6.0。该酶在30~70℃、pH 4.5~9.0之间具有优良的稳定性。该酶在50℃和pH 6.0下水解支链淀粉的Km、Vmax分别为4.0324 mg/mL和0.1841 mg/(min.mL)。研究了不同金属离子对该酶活性和热稳定性的影响,发现Ca2+、Mg2+、Mn2+等金属离子对于该酶具有显著的激活效果,并且Ca2+对该酶的热稳定性具有很好的提升作用。

英文摘要:

Debranching enzymes are essential for starch saccharification processes with their activity for cleavage of 1,6-glucoside linkage in starch molecules.In this study,a novel debranching enzyme from the thermophilic Bacillus sp.CBB272 was purified using the combination of ammonium sulfate precipitation,weak ion-exchange and strong ion-exchange.The purified enzyme possessed the relative molecular weight of 70 kD on SDS-PAGE.The enzyme exhibited the maximal activity at 70℃ and pH 6.0 with excellent stabilities at a temperature range from 30 ℃ to 70 ℃ and pHs from 4.5 to 9.0.At pH 6.0 and 50 ℃ its Km and Vmax for amylopectin were 4.0324 mg/mL and 0.1841 mg/(min·mL),respectively.The enzyme was strongly activated by Ca2+,Mg2+ and Mn2+ and Ca2+ significantly increased its thermostability.

查看全文 查看/发表评论 下载PDF阅读器