Purification and properties of a basic inducible protein, ICG with chitinase and ${\beta}-1,3-glucanase$ activities from rice cell suspension culture media treated with chitooligosaccharides

Chitooligosaccharides 처리에 의해 유도되는 chitinase, ${\beta}-1,3-glucanase$ 활성 보유 벼 염기성 단백질 ICG의 분리 및 성질

A basic inducible protein, ICG, containing chitinase and ${\beta}-1,3-glucanase$ activity concomittantly was purified from cell suspension culture media of rice after the treatment of chitooligosaccharides. The isolated ICG enzyme gave a single band on native and SDS polyacrylamide gel electrophoresis and its molecular weight was estimated to be 52.53 kd. The optimal temperature and optimal pH of both enzyme activities in ICG were $60^{\circ}C$, pH 6.0 for chitinase activity and $37^{\circ}C$, pH 4.0 for ${\beta}-1,3-glucanase$ activity. $K_M$ and $V_{max}$ values for chitinase were 0.474 mM. 2.997 nM/min., and those for ${\beta}-1,3-glucanase$ were 1.004 mM 0.739 nM/min. respectively. TLC analysis of the chitooligosaccharide hydrolysates with ICG enzyme indicated that ICG acts as endochitinase.

벼 세포 현탁배양여액으로부터 chitooligosaccharides에 의해 유도된 염기성 단백질 ICG를 순수분리하였다. 본 단백질은 chitin과 laminarin을 가수분해하므로 chitinase와 ${\beta}-1,3-glucanase$ 활성을 함께 보유하고 있는 것으로 나타났으며, 벼잎 단백질 RCG-2와는 달리 lysozyme 활성을 가지고 있지 않았다. 분자량이 52.53 kd인 본 효소의 chitinase 활성은 pH 5.0, $60^{\circ}C$, ${\beta}-1,3-glucanase$ 활성을 pH 4.0, $40^{\circ}C$의 조건에서 최대로 나타났다.$NAG_5$에 대한 $K_M$ 및 $V_{max}$ 수치는 각각 0.474 mM, 2.997 nM/min., laminarin에 대한 것은 각각 1.004 mM, 0.739 nM/min.로 나타나, ICG는 RCC-2보다 높은 기질친화성을 가지고 있으며 chitin을 chitooligosaccharide로 분해하는 endo형 chitinase로 판명되었다.