Chitinase, ${\beta}-1,3-glucanase$ 및 lysozyme 효소활성을 보유한 벼잎 산성단백질 RCG-2

Isolation and Properties of a Protein, RCG-2, Having Chitinase, ${\beta}-1,3-Glucanase$ and Lysozyme Activities from Rice Leaves

벼잎의 산성용액 추출물로부터 ion exchange chromatography chitin affinity chromatography chromatofocusing gel slicing 등의 방법으로 단백질 RCG-2를 순수분리하였다. 본 단백질은 chitin과 laminarin을 가수분해하므로 chitinase와 ${\beta}-1,3-glucanase$ 활성을 함께 보유하고 있는 것으로 나타났으며, 이외에도 M. lysodeiktikus cell wall을 가수분해하는 lysozyme 활성도 보유하는 것으로 판명되었다. 분자량이 29.77 kd인 본 효소의 chitinase 활성은 pH 4.0에서, ${\beta}-1,3-glucanase$ 활성은 pH 7.0에서 최대로 나타났고, 최적온도는 두 효소 활성 모두 $40^{\circ}C$ 이었다. chitin에 대한 $K_M$ 값은 7.86 mM, $V_{max}$는 $0.025\;{\mu}M/min$, laminarin $({\beta}-1,3-glucan)$에 대한 것은 각각 5.95 mM, $0.16{\mu}\;M/min.$ 이었으며, 정제된 효소는 chitin을 chitooligosaccharide로 분해하는 것으로 나타나서 endochitinase로 판명되었다.

An acidic protein, RCG-2, containing chitinase and ${\beta}-1,3-glucanase$ activity conccurrently was purified from rice leaves by chromatofocusing and gel slicing. The purified enzyme gave a single band on polyacrylamide gel electrophoresis and its molecular weight was appeared to be 29.7 kd using SDS-PAGE. This enzyme also had lysozyme activity. The optimal temperature for both enzyme activities was $40^{\circ}C$, optimal pH were 4.0 for chitinase activity and 7.0 for ${\beta}-1,3-glucanase$ activity. $K_M$ and $V_{max}$ values for chitinase were 7.86 mM and $0.025\;{\mu}M/min.$, and those for ${\beta}-1,3-glucanase$ were 5.95 mM and $0.16\;{\mu}M/min.$ respectively. TLC analysis of the enzyme hydrolysates of chitooligosaccharides indicated that this enzyme acts as endochitinase.