Churilova I V, Maksimov V I, Klesov A A
Biokhimiia. 1979 Nov;44(11):2100-2.
Cellobiose may exert different effects on the activities of various endoglucanases. The endoglucanases of T. reesei and Rapidase are noticeably suppressed by cellobiose at concentrations above 3 mM. On the other hand, a low molecular weight endoglucanase from T. koningii is activated by cellobiose, whereas high molecular weight endoglucanases from the same source are inhibited by cellobiose. A detailed kinetic analysis of the effects showed that the low molecular weight endoglucanase is activated by a transglycosylation mechanism, in which cellobiose acts as an additional nucleophile. At saturating concentrations of cellobiose (Ks = 15 mM) the enzyme activity is increased 6-fold. Such a specific mechanism of activation manifests itself in an acceleration of random cleavage of CM-cellulose by the low molecular weight endoglucanase, which can be recorded by a viscosimetric technique. However, its action does not accelerate the production of soluble reducing sugars.
纤维二糖可能对各种内切葡聚糖酶的活性产生不同影响。里氏木霉和Rapidase的内切葡聚糖酶在浓度高于3 mM时会受到纤维二糖的显著抑制。另一方面，康宁木霉的一种低分子量内切葡聚糖酶被纤维二糖激活，而来自同一来源的高分子量内切葡聚糖酶则被纤维二糖抑制。对这些影响的详细动力学分析表明，低分子量内切葡聚糖酶通过转糖基化机制被激活，其中纤维二糖充当额外的亲核试剂。在纤维二糖饱和浓度（Ks = 15 mM）下，酶活性增加6倍。这种特定的激活机制表现为低分子量内切葡聚糖酶对CM-纤维素随机切割的加速，这可以通过粘度测定技术记录下来。然而，其作用并不会加速可溶性还原糖的产生。
