Thermostable Chitosanase from Bacillus sp.Strain CK4 : Its Purification, Characterization, and Reaction Patterns

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A thermostable chitosanase, purified 156-fold to homogeneity in an overall yield of 12.4%, has a molecular weight of about 29,000±2,000,and is composed of monomer. The enzyme degraded soluble chitosan, colloidal chitosan, and glycol chitosan, but did not degrade chitin or other β-linked polymers. The enzyme activity was increased about 2.5-fold by the addition of 10 mM Co^<2+> and 1.4-fold by Mu^<2+>. However, Cu^<2+> ion strongly inhibited the enzyme. Optimum temperature and pH were 60℃ and 6.5,respectively. The enzyme was stable after heat treatment at 80℃ for 30 min or 70℃ for 60 min and fairly stable in protein denaturants as well. Chitosan was hydrolyzed to (GlcN)_4 as a major product, by incubation with the purified enzyme. The effects of ammonium sulfate and organic solvents on the action pattern of the thermostable chitosanase were investigated. The amounts of (GlcN)_3-(GlcN)_6 were increased about 30% (w/w) in DAC 99 soluble chitosan containing 10% ammonium sulfate, and (GlcN)_1 was not produced. The monophasic reaction system consisted of DAC 72 soluble chitosan in 10% EtOH also showed no formation of (GlcN)_1,however, the yield of (GlcN)_3 〜 (GlcN)_6 was lower than DAC 99 soluble chitosan-10% ammonium sulfate. The optimal concentration of ammonium sulfate to be added was 20%. At this concentration, the amount of hexamer was increased by over 12% compared to the water-salt free system.
社団法人日本農芸化学会の論文
2001-04-23

Thermostable Chitosanase from Bacillus sp.Strain CK4 : Its Purification, Characterization, and Reaction Patterns

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