Some properties of thermostable .betha.-galactosidase of bacillus coagulans

열내성이 강한 bacillus coagulans의 $\beta$-Galactosidase의 특성에 대하여

  • 이홍금 (서울대학교 미생물학과) ;
  • 홍순우 (서울대학교 미생물학과) ;
  • 하영칠 (서울대학교 미생물학과) ;
  • 이정치 (일동제약 주식회사) ;
  • 김태한 (일동제약 주식회사)
  • Published : 1980.03.01

Abstract

A thermostrable ${\beta}-galactosidase$ (${\beta}-galactoside$ 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 $60^{\circ}C$ and pH 7.5, respectively. Kinetic determinations at $55^{\circ}C$ established a Km of 3.3mM for the chromogenic substrate onitorphenyl ${\beta}-D-galactopyranoside$ (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 $60^{\circ}C$ 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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