Abstract

The cyclodextrin glucanotransferase (CGTase) was purified from the culture broth of Bacillus stearothermophilus by ammonium sulfate precipitation and affinity chromatography. The specific activity of the CGTase increased by about 31-fold from 111.5 U/mg protein to 3445.0 Ulmg protein. The SDSPAGE indicated that the purified CGTase was homogeneous and the molecular weight of the purified CGTase was about 78,000. The optimum pH and temperature was 6.0 and $60^{\circ}C$, respectively. This enzyme was stable from pH 5.5-10.0. The enzyme retained its full activity at the incubation temperature up to $60^{\circ}C$ and calcium ion increased the thermal stability. The isoelectric point was about 4.8.

Bacillus stearothermophilus가 생산하는 cyclodextrin glucanotransferase (CGTase)를 ammonium sulfate 법과 affinity chromatography법에 의해 정제하였다. 이 CGTase의 비활성은 11.5U/mg protein에서 33445.0U/mg protein으로 증가하였다. 이 효소의 분자량을 측정하기 위해 SDS-PAGE를 실시한 결과 분자량은 약 7,800이었다. 이 효소의 최적 pH와 온도는 각각 6.0과 $60^{\circ}C$이었다. 이 효소는 pH5.5와 10.0에서 안정하였다. 이 효소에 calcium ion을 첨가하였더니 열안정성이 증가하였다. 이 효소의 등전점은 약 4.8 이었다.

Keywords

• Bacillus stearothermophilus;
• cyclodextrin glucanotransferase;
• affinity chromatography