Kinetics of Hydrolysis Reaction of Chitin Oligomer by a Chitinase Purified from Bacillus subtilis

摘要

Chitinases were extracted and purified from Bacillus subtilis, a bacterium generatedrnfrom natto, which is a traditional Japanese food. First of all, the best culture condition,rnculture medium and culture time were decided. Secondly, the crude extracelluler enzymernwas obtained by filtration and purified by ion exchange chromatography. As the result,rnthree major fractions with high chitinase activity were obtained and those were named asrnChi-1～3. The molecular weights of Chi-1～3 were 85, 30 and 55 kDa, respectively. Thernoptimum pH and the optimum temperature of Chi-1～3 were obtained. For Chi-1～3, thernmaximum reaction rate and the Michaelis constant were obtained for the hydrolysis ofrnglycol chitin. Chi-3 was found to hydrolyze N-acetyl-chito-oligosaccharidesrn(GlcNAc)_n as follows; (GlcNAc)_5 → (GlcNAc)_3 ＋ (GlcNAc)_2, and (GlcNAc)_4→rn2(GlcNAc)_2.