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KMID : 0364819800180010007
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Korean Journal of Microbiology
1980 Volume.18 No. 1 p.7 ~ p.14
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Some properties of thermostable β-galactosidase of bacillus coagulans
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이홍금
홍순우/하영칠/이정치/김태한
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Abstract
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A thermostrable β-galactosidase (β-galactoside galactohydorlase, EC 3.2.1.23) was inducible in Bacillus coagulans by lactose and D-glactose. The enzyme was purified 87 fold, and the optimum temeprature and pH for actiivity were determined to be 60℃ and pH 7.5, respectively. Kinetic determinations at 55℃ established a Km of 3.3mM for the chromogenic substrate onitorphenyl β-D-galactopyranoside (ONPG). Galactose and lactose were competitive inhibitors with Ki of 6.1mM and 4.9mM, respectively. The enzyme ws relatively thermostable. The crude enzyme was inactivated about 20% after 20 min of exposure at 60℃ and the purified was about 50%. Maximal enzyme activity required Mn^++, and for the thermal stabilization Fe^++ and Ca^++ were necessary.
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