STEREOCHEMICAL COURSE OF HYDROLYSIS CATALYZED BY CELLULOMONAS-FIMI CENE, A MEMBER OF A NEW FAMILY OF BETA-1,4-GLUCANASES

The gene for a previously identified, extracellular, 120 kDa cellulose -binding protein (Cbp120) was isolated from a Cellulomonas fimi genomi c library and expressed in Escherichia coli. Qualitative analysis of C M-cellulose hydrolysis shows that Cbp120 is an endo-beta-1,4-glucanase . Cbp120, now renamed CenE, catalyzes hydrolysis of cellohexaose with inversion of anomeric carbon configuration, characteristic of a single displacement reaction. Partial sequencing of its gene shows that CenE has significant sequence similarity with the catalytic domains of fiv e enzymes from cellulolytic bacteria. It is proposed that the six enzy mes form a new family of beta-1,4-glucanases. CenE is the first enzyme from this family to be characterized stereochemically. (C) 1994 Acade mic Press, Inc.