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Thermostable chitosanase from Bacillus sp. strain CK4: Its purification, characterization, and reaction patterns
Ist Teil von
Bioscience, biotechnology, and biochemistry, 2001-04, Vol.65 (4), p.802-809
Ort / Verlag
Tokyo: Japan Society for Bioscience, Biotechnology, and Agrochemistry
Erscheinungsjahr
2001
Link zum Volltext
Quelle
Taylor & Francis
Beschreibungen/Notizen
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 Mn
2+
. However, Cu
2+
ion strongly inhibited the enzyme. Optimum temperature and pH were 60°C and 6.5, respectively. The enzyme was stable after heat treatment at 80°C for 30 min or 70°C 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.