Abstract
Botrytis cinerea T91-1 has shown to produce at least four different polygalacturonases in a liquid medium containing citrus pectin as a carbon source. One of the enzymes, its molecular weight was estimated as 37 kDa by denatured polyacrylamide gel electrophoresis, was purified by a series of procedures including acetone precipitation, ion exchange, heparin affinity, and reverse phase column chromatographies. By viscometric analysis, the enzyme was revealed as an endo-polygalacturonase. The enzyme activity was inhibited by divalent cations such as $Ca^{2+}$, $Co^{2+}$, and $Cu^{2+}$. Km and Vmax for polygalacturonic acid hydrolysis were 0.33 mg/ml and 28.6 nM/min, respectively. The optimum temperature for enzymatic activity was $55^{\circ}C$ and the enzyme showed optimal pH values between 4.0 and 4.5. The enzyme was stable up to 12 hours in the range of pH 4 to 7 and at the temperature below $30^{\circ}C$. Amino acid sequence from N-terminal up to 6 amino acids determined by Edman degradation showed little homology with polygalacturonases from fungi and plants.
식물 병원진균 Botrytis cinerea가 분비하는 polygalacturonase의 동위효소 중에서 endo-type의 polygalacturonase를 Phenyl-Toyopearl column chromatography와 DEAE-, Mono Q-, heparin-high performance liquid chromatography법으로 약 68배 정제하였고 sodium dodecylsulfate(SDS)를 포함하는 polyacrylamide gel electrophoresis로 분석하여 단일 띠를 확인하였다. 정제한 효소의 분자량은 SDS-polyacrylamide gel에서 37 kDa로 측정되었으며 약산성인 조건과 $30^{\circ}C$ 이하에서 안정하였으며 최고 활성은 pH 4.5와 $55^{\circ}C$의 온도에서 관찰되었다. 정제한 효소는 polygalacturonic acid를 endo-type으로 가수분해하였고, polygalacturonic acid에 대한 $K_m$값과 $V_{max}$값은 각각 1.1 mg/ml과 250 nmol/min이었다. N-말단의 아미노산 서열을 결정하여 본 결과, 식물이나 다른 진균류에서 보고된 아미노산 서열과 유사성이 없었다.
