Purification and Characterization of an Extracellular Xylanase of Bacillus stearothermophilus

Bacillus stearothermophilus 가 생산하는 Xylanase의 정제 및 특성

An extracellular xylanase of Bacillus stearothemophilus was purified to a single protein through a sequency of operations including ammonium sulfate fractionation, DEAE Sepharose CL-6B ion exchange chromatography, Sephadex G-100 gel filtration and heat treatment. The purified enzyme had a moleular weight of 170, 000. the pH and temperature optima for the enzyme activity were pH 9.0 and $55^{\circ}C$, respectively. The activity was enhanced by $co^{2+} \; and\; Mn^{2+}$, and inhibited by $Hg^{2+}$. Pattern of hydrolysis demonstrated that the xylanase was an endo-splitting enzyme able to break down larchwood xylan at random giving xylobiose and xylotriose as the main end products.

토양 분리균인 B.stearothermophilus가 생산하는 xylanase를 ammonium sulfate 분획, DEAE-Sepharose CL-6B ion exchange chromatography, Sephadex G-100 gel 여과 및 열처리 등의 과정을 거쳐 단일 단배질로 분리 정제하였다. 170,000의 분자량을 본 정제 xylanase는 pH8과 pH10 사이의 넓은 최적 pH를 보였으며 $55^{\circ}C$에서 최대 활성을 나타내었다. $55^{\circ}C$에서 2시간의 열처리에 의해서도 활서의 손실이 거의 없을 정도로 열에 매우 안정하였으며 $co^{2+}$와 $Mn^{2+}$에 의해서 현저한 활성화 효과를 보였다.