HYDROLYSIS OF VARIOUS CELLULOSES, (1-]3),(1-]4)-BETA-D-GLUCANS, AND XYLOGLUCAN BY 3 ENDO-TYPE CELLULASES

In explaining the fine substrate specificity of three kinds of highly purified endo-type cellulases (En-l, EG-1, and Endo-2) from the fungi Irpex lackeus (Fr.: Fr.) Fr,, Aspergillus niger van Tieghem, and Trich oderma reesei Simmonds, respectively, several pure cellulosic material s with different crystallinities derived from Cellulose I type were em ployed for the substrates. The modes of action of these cellulases wer e investigated comparatively using barley glucan and xyloglucan of tam arind seeds (Tamarindus indica L.). These enzymes revealed typical end o-type attacks producing several kinds of cellooligosaccharide from am orphous cellulose with low crystallinity. Only Endo-2 lessened the <(D P)over bar> (degree of polymerization) of amorphous and crystalline ce lluloses less than did the other two cellulases, whereas this cellulas e was adsorbed on crystalline cellulose such as bacterial cellulose to a greater extent than that made by others. Three endo-type cellulases hydrolyzed barley glucan in an endowise fashion to produced several m ix-linked oligosaccharides with slightly different patterns. Of these mix-linked oligosaccharides, G4G3G and G4G3G4G were further hydrolyzed only by Endo-8. Xyloglucan scarcely was hydrolyzed by these endo-type cellulases, whereas xyloglucan tetradecasaccharide was hydrolyzed onl y by EG-1. From these results, it seems that the modes of action of in dividual endo-type cellulases from,different fungi strongly: are depen dent on the stereochemical structures of the substrates.