摘要
通过Bio GelP 60分子筛和DEAE 与Q sepharose离子交换层析等手段 ,分离纯化了棘孢曲霉SM L2 2纤维素酶系中五种内切酶组分EGⅡ 1、EGⅡ 2、EGⅢ 1、EGⅢ 2和EGⅣ ,并且对这五种内切酶组分的基本性质进行了研究。通过SDS PAGE和IEF电泳测得其分子量分别为 38 7,34 4,31 4,36 9和 2 3 7kD ,等电点分别为pH <3 5,<3 5,4 9,4 5和 5 0。 5个酶组分均属酸性纤维素酶 ,最适pH在 3 5～ 4 0之间 ;最适温度分别为 55℃、60℃、( 60～ 70 )℃、( 60～70 )℃和 60℃。各酶组分有较宽的pH稳定性 ;温度稳定性表现为EGⅡ 1 >EGⅡ 2 >EGⅢ 1>EGⅢ 2 >EGⅣ。EGⅡ 1和EGⅡ 2有较高的底物专一性 ,而EGⅢ 1、EGⅢ 2和EGⅣ对木聚糖有交叉活性。Fe2 +对除EGⅣ以外的四种酶组分都有激活作用 ,尤其是对EGⅢ 2有强烈的激活作用。动力学分析表明各纤维素酶组分对底物亲和力的大小与酶的催化率之间并无相关性。
The five endoglucanases(CMCase)components from Aspergillus aculeatus SM\|L22 were separated and purified by exclusion chromatography and ion\|exchange chromatography.Five components(EGⅡ-1,EGⅡ-2,EGⅢ-1,EGⅢ-2 and EGⅣ)had molecular weights of 38.7,34.4,31.4,36.9 and 23.7kD by SDS\|PAGE,respectively,and IEF showed their pI were pH<3.5,<3.5,4.9,4.4 and 5.0,respectively.All of them have maximum reactive activities at pH 3.5～4.0;and the optimum temperatures were 55℃,60℃,60℃～70℃,60℃～70℃ and 60℃,respectively.EGⅡ-1 and EGⅡ-2 can only act such morphological substrates as CMC or phosphated cellulose,but EGⅢ-1,EGⅢ-2 and EGⅣ can active xylan also.The activities of all components were stimulated by Fe 2+ except EGⅣ,EGⅢ-2 was activited mostly by Fe 2+ .The kinetics' showed that there were no relativies between the affectivity of cellulases and its K m.
出处
《微生物学报》
CAS
CSCD
北大核心
2001年第4期469-474,共6页
Acta Microbiologica Sinica
基金
国家自然科学基金! (3 0 0 70 1 80 )
山东大学微生物技术国家重点实验室开放项目资助&&
