Abstract
Enzymatic properties of avicelase, carboxymethyl cellulase (CMCase) and P-glucosidase produced by Cellulomonas sp. YE-5 were studied. Optimal temperature and pH of avicelase were 40t and 6.0, and those of CMCase and P-glucosidase were $45^{\circ}C$ and 6.5. Avicelase and CMCase were stable between pH 5.0 and 9.5, and &glucosidase was stable between pH 5.5 and 8.0. Avicelase and P-glucosidase were inactivated when incubated at $35^{\circ}C$ for 6 hrs, and CMCase was at $40^{\circ}C$ for 6 hrs. All cellulases were strongly inhibited by $Cu^{2+} \; and \; Zn^{2+}. K_m$ values of avicelase for avicel, CMCase I and CMCase II for CM-cellulose, and ($\beta$-glucosidase for p-nitrophenyl-$\beta$-D-glucoside (PNPG) were 4.76, 16.4, 16.4 $\mu g$/ml and 3.51 mM, respectively.
Cellulomonas sp.YE-5가 생산하는 cellulase를 분리, 정제하여 효소의 특성을 알아보았다. Avicelase, CMCase, $\beta$-glucosidase의 반응 최적온도은 각각 40, 45, $40^{\circ}C$이었고, 반은 최적 pH는 5.5, 6.0 그리고 6.0이었다. 효소의 열안정성은 30~$70^{\circ}C$에서 6시간 처리하였을 때 avicelase와 $\beta$-glucosidase는 $50^{\circ}C$ 이상에서 거의 실활하였고, CMCase는 $50^{\circ}C$에서 약 40% 의 활성을 유지하였다. 효소의 안정성에 미치는 pH의 영향은 $25^{\circ}C$에서 24시간 처리하였을 때 avicelase와 CMCase는 PH 5.0~9.0 사이에서 안정하였으며, $\beta$-glucosidase는 pH 5.0~8.0 사이에서 안정하였다.
