THE RESISTANCE OF CELLULASES AND XYLANASES TO PROTEOLYTIC INACTIVATION

The sensitivity of a range of cellulases and xylanases to proteolytic inactivation was investigated. The xylanases, all the Clostridium ther mocellum cellulases and cellulase E from Pseudomonas fluorescens subsp . cellulosa exhibited no decrease in catalytic activity during a 3-h i ncubation with proteinases of the small intestine. Under these conditi ons, the control Escherichia coli enzymes analysed had half-lives of 4 .3-13.5 min. The addition of substrate significantly decreased the sen sitivity of proteinase-labile enzymes to inactivation. The significanc e of these data in relation to the use of cellulases and xylanases for improving animal nutrition is discussed.