ANALYSIS OF A CELLODEXTRINASE CLONED FROM RUMINOCOCCUS-FLAVEFACIENS FD-1

A cellulase gene from Ruminococcus flavefaciens FD-1 had previously be en cloned in Escherichia coli. The product of this gene, CelA, was pur ified from E. coli and characterised. This 39 kDa cellulase is antigen ically related. and of similar mass. to a protein in R. flavefaciens. The enzyme has cellodextrinase activity with predominantly exo-type ac tion. CelA activity was optimal at pH 6.5 and 41-degrees-C, and was in hibited in the presence of divalent metal cations. The K(m) and V(max) were determined as 0.68 mM and 1.89 mumol min-1 mg-1 of CelA, respect ively. Cellobiose was the major end product of cellodextrin hydrolysis , and our results suggest that cellobiose is a competitive inhibitor o f CelA.