Adsorption of Bacillus subtilis endo-beta-1,4-glucanase to cellulosic materials

The intact and the truncated endo-beta-1,4-glucanase expressed in Bacillus megaterium by a B. subtilis gene were purified and its adsorption characteristics to cellulosic materials were investigated. The intact enzyme was purified by affinity towards insoluble cellulose and Mono-Q chromatography. The truncated enzyme was purified by gel filtration and chromatofocusing. The molecular activities of these enzymes towards the soluble substrates were identical. Optimum pH and temperature of these two types of enzyme were same, 5.5 and 60 degrees C, respectively. However, the insoluble substrate, Avicel, was hydrolyzed slowly by the intact endoglucanase while the truncated endoglucanase did not hydrolyze the Avicel. Isoelectric points of the intact and the truncated enzyme were 6.2 and 5.6, respectively. In a Sephadex column the large form of intact endoglucanase was eluted later than the small form of truncated enzyme. Only the intact enzyme was strongly adsorbed to Avicel. The practical maximum adsorption was about 20 mg/g of Avicel at pH 6.0 and 4 degrees C.