A Clostridium cellulovorans gene, engD, codes for both endo-β-1,4-glucanase and cellobiosidase activities

A 5.8 kbp DNA fragment from Clostridium cellulovorans (ATCC 35296) containing endo-β-1,4-glucanase (1,4-β-d-glucan glucanohydrolase, carboxymethylcellulase, CMCase; EC 3.2.1.4) gene, engD was cloned in Escherichia coli. The clone harboring a subcloned 3.8 kb fragment in plasmid, pEQ52V, produced an enzyme that showed both endo-β-1,4-glucanase activity as well as cellobiosidase activity. Zymograms with the engD encoded enzyme with carboxymethyl-cellulose as the substrate indicated that the molecular mass of the active protein was 50 000.