Effect of Metal Ions and Substrate on the Thermostability of ${\alpha}-Amylase$ from Bacillus licheniformis

Bacillus licheniformis가 생산하는 ${\alpha}-Amylase$의 열안정성에 미치는 금속이온 및 기질의 영향

  • Yoon, Jong-Won (Department of Food Science and Technology and Research Center for New Bio-materials in Agriculture, Seoul National University) ;
  • Park, Kwan-Hwa (Department of Food Science and Technology and Research Center for New Bio-materials in Agriculture, Seoul National University)
  • 윤종원 (서울대학교 식품공학과,농업생물 신소재 연구센터) ;
  • 박관화 (서울대학교 식품공학과,농업생물 신소재 연구센터)
  • Published : 1992.08.01

Abstract

The ${\alpha}-amylase$ from Bacillus licheniformis was purified and its thermostability in the presence of substrate and metal was ions investigated. Comparing D-values of the enzyme obtained in the presence of $Ca^{++}$, $B^{+++}$ and both $Ca^{++}$ and $B^{+++}$, the thermostability of the enzyme was markedly enhanced by the addition of metal ions. $Ca^{++}$ and $B^{+++}$ exhibited a protective action, the former ion being more effective, and both ions showed a synergistic effect. The enthalpy of activation for the thermal inactivation in the presence of metal ion was 320.2 kJ/mole for $Ca^{2+}$ ion, 212.9 kJ/mole for $B^{+++}$, while it was 183.9 kJ/mole in the absence of metal ions. In the thermal inactivation for 30 min at $96^{\circ}C$, the residual activity in the presence of 30% (w/w) starch was 51.0%, whereas the presence of $Ca^{++}$ ion additionally provided a remarkable thermo-resistance.

Keywords

${\alpha}-amylase$;thermostability;Bacillus licheniformis;metal ion effect