STUDIES ON CELLULOLYTIC ENZYMES .6. SPECIFICITY AND MODE OF ACTION ON DIFFERENT SUBSTRATES OF A CELLULASE FROM PENICILLIUM NOTATUM

Lichenin (a mixed β-1.4 and β-1.3 glucan) is the only polysaccharide of several tested that is degraded by the enzyme. The Penicillium cellulase has a limited ability to attack crystalline cellulose in contrast to amorphous cellulose, which is readily attacked. Cellobiose is not attacked, while the rate of degradation of the higher members of the series of oligoglucosides increases with increasing D.P. The half-lifes of cellotriose, cellotetraose and cellopentaose were found to be 3700, 50, and 3 min, respectively. The central bonds of cellotetraose and cellopentaose were found to be the preferred points of cleavage. The Km values for the oligosaccharides displayed a pronounced tendency to decrease with chain length. Kinetic data suggested that the specificity region of the cellulase is five glucose units in length. © 1969.