Characterization of Three β-Mannanases of an Alkalophilic Bacillus sp.(Biological Chemistry)

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Three extracellular β-mannanases (M-I, M-II, and M-III) of an alkalophilic Bacillus sp. (AM-001) were purified to an electrophoretically homogenous state. Molecular weights and pI values of the purified enzymes (M-I, M-II, and M-III) were 58,000, 59,000, and 42,000 by SDS-PAGE and 5.9, 5.7, and 5.1 by isoelectric focusing, respectively. These enzymes were most active at pH 9.0 and 60℃(M-I and M-II) and pH 8.5 and, 65℃(M-III). The enzymes were activated slightly by cysteine, and inhibited strongly by Ag^+ and N-bromosuccinimide. Michaelis constants (Km) of the M-I enzyme for β-mannans from copra, locust bean, and konjak were 2.0, 3.8, and 7.7 mg/ml, and maximum velocities (V_<max>) for these saccharides were 730, 1470, and 1880U/mg・protein, respectively. The kinetic properties of M-II and M-III enzymes were almost the same as those of M-I. About 22, 16, 15, and 2.5% of the β-1,4-mannosidic linkages in β-mannans from copra, konjak, locust bean, and guar bean were hydrolyzed by the M-I enzyme, and the major components in the digests were di-, tri-, and tetra-saccharides. These enzymes hydrolyzed β-1,4-mannooligosaccharides larger than mannotriose.
社団法人日本農芸化学会の論文
1988-03-23