MICROCRYSTALLINE CELLULOSE-HYDROLYZING CELLULASE (ENDO-CELLULASE) FROM TRICHODERMA-REESEI CDU-11

A microcrystalline cellulose (Avicel)-hydrolyzing cellulase (an endocellulase) was isolated from a preparation of Trichoderma reesei CDU-11 and purified successively by DEAE-Sepharose CL 6B and Concanavalin A-Sepharose column chromatography, and preparative electrophoresis and on Sephadex G-100 gel filtration. The cellulase preparation showed a single protein band on SDS-PAGE slab and gel disc electrophoresis. Its molecular weight was estimated to be 64,000 by Sephadex G-100 gel filtration and 67,000 by SDS slab electrophoresis. The isoelectric point was at pH 4.75 on polyacrylamide gel electric focusing. This cellulase hydrolyzed more specifically water insoluble microcrystalline cellulose such as Avicel rather than water soluble cellulose such as carboxymethylcellulose. It produced glucose, cellobiose and cellotriose from cellotetraose and cellohexaose, and it produced a significant amount of glucose and cellobiose from Avicel. Based on these results, it appears that the cellulase should be regarded as an endo-type cellulase, although it hydrolyzes Avicel relatively easier than CM-cellulose. We obtained no evidence that this cellulase is an exo-type one named cellobiohydrolase (CBH) in the systematic nomenclature.