Studies on the Production of $\beta$-Galactosidase by Lactobacillus sporogenes - Characterization of $\beta$-Galactosidase -

Lactobacillus sporgenes에 의한 $\beta$-Galactosidase생산에 관한 연구 -$\beta$-Galactosidase의 효소학적 성질-

  • Kim, Young-Man (Il Dong Pharm. Co., Ltd.) ;
  • Lee, Jung-Chi (Il Dong Pharm. Co., Ltd.) ;
  • Chung, Pil-Keun (Il Dong Pharm. Co., Ltd.) ;
  • Park, Yong-Jin (Department of Food and Nutrition Dong Duck Women′s University) ;
  • Yang, Han-Chul (Department of Food Technology, Korea University)
  • Published : 1983.09.01

Abstract

Extracellular $\beta$-galactosidase was prepared from a culture of Lactobacillus sporogenes, a spore-forming lactic acid bacterium. The enzyme functioned optimally at pH 6.8 and at 6$0^{\circ}C$ o-nitrophenyl-$\beta$-D-galactopyranoside (ONPG) in 0.05M sodium phosphate buffer. The activation energy of the enzymatic hydrolysis of ONPG was about 16,000 cal/mole below $50^{\circ}C$ and 11,300 cal/mole above the temperature. It was fairly stable over a pH range from 4.0 to 8.0 losing only less than 30% of its activity after hearting at 6$0^{\circ}C$ and pH 6.8 for 3 hours. Metal ions showed no significant effect on the enzyme activity, whereas L-cysteine exerted a slight stimulatory effect at the concentration of 10mM. The km values were 1.48mM for ONPG and 64.5mM for lactose. Hydrolysis of ONPG by the enzyme was product-inhibited by galactose (Ki=13.3mM, competitive inhibition) and by glucose(Ki= 11.4mM, uncompetitive type). The enzyme activity was also noncompetitively inhibited in the presence of lactose (Ki= 17.8mM).

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