脱墨用棘孢曲霉SM-L22纤维素酶系中内切酶的纯化及性质

通过Bio-Gel P-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-L22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23.7kD,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.

PURIFICATION AND PROPERTIES OF ENDOGLUCANASES FROM ASPERGILIUS ACULEATUS SM-L22

The five endoglucanases(CMCase) components from Aspergillus aculeatus SM-L22 were separated and purified by exclusion chromatography and ion-exchange chromatography. Five components(EG II-1, EG II-2, EG III-1, EG III-2 and EG IV) had molecular weights of 38.7, 34.4, 31.4, 36.9 and 23.7 kD 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 degrees C, 60 degrees C, 60 degrees C-70 degrees C, 60 degrees C-70 degrees C and 60 degrees C, respectively. EG II-1 and EG II-2 can only act such morphological substrates as CMC or phosphated cellulose, but EG III-1, EG III-2 and EG IV can active xylan also. The activities of all components were stimulated by Fe2+ except EG IV, EG III-2 was activited mostly by Fe2+. The kinetics' showed that there were no relativies between the affectivity of cellulases and its Km.