title: [Cellobiose as a regulator of endoglucanase activity of cellulase complexes. Mechanism of the regulation].
abstract: 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.
mesh_terms: D002475:Cellobiose / Q000378:metabolism*; D002480:Cellulase / Q000378:metabolism*; D004187:Disaccharides / Q000378:metabolism*; D005936:Glucans; D006026:Glycoside Hydrolases / Q000378:metabolism*; D007700:Kinetics; D003904:Mitosporic Fungi / Q000201:enzymology*; D013045:Species Specificity; D014242:Trichoderma / Q000201:enzymology*
chemical_list: D004187:Disaccharides; D005936:Glucans; D002475:Cellobiose; D006026:Glycoside Hydrolases; D002480:Cellulase
vernacular_title: Tsellobioza-peguliator aktivnosti endogliukanaz tselliulaznykh kompleksov. Mekhanizm peguliatsii.