ISOLATION AND PURIFICATION OF ISOENZYMES OF CELLOBIOHYDROLASE-I AND CELLOBIOHYDROLASE-II OF TRICHODERMA-REESEI USING LPLC METHODS

Five cellulases were fractionated from a commercial cellulase preparation (CelluclastTM) Two isoenzymes of cellobiohydrolase I (CBHI)(pI = 4.1) could be proved to be real exo‐glucanases due to their activity towards MU (=methylumbelliferyl)‐lactoside being inhibited by cellobiose (5 mM) and due to production of cellobiose from carboxymethylcellulose (CMC) as the sole final product.Two isoenzymes of CBHII (pI=6.15, 6.0) were shown to act as endo‐glucanases because they produced glucose, cellobiose and cellotetraose from CMC and because they were not inhibited by cellobiose when decomposing MU‐lactoside. Results confirm recent reports in the literature classifying CBHI and CBHII as exo‐type and endo‐type cellulases, respectively. Both the CBHI and the CBHII isoenzymes were shown to be active towards CMC and amorphous cellulose.CBHI and CBHII reactions could be differentiated from one another by the velocities of decomposition of CMC: CBHI acts slowly and linearly whereas CBHII acts strongly and exponentially.The fifth of the purified enzymes must be classed as a conventional endoglucanase which exhibits activity towards CMC but fails to be active towards MU‐lactoside and amorphous cellulose. Copyright © 1990 Akademie‐Verlag