Abstract
The prcx.iuction of extracellular 1,4-${\beta}$-glucanase by Cellulomonas sp. CS1-1 on microcrystalline cellulose, sigmacell was maximal after 5-day cultivation as 280 units/mL, which was three times higher than the level produced on carboxymethyl cellulose. A carboxymethyl cellulase containing the carbohydrate of 8.2% was purified from the culture filtrate by successive procedures of column chromatographies. Purification factor was calculated as 22-folds with the specific carboxymethyl cellulase activity of 31.9 units/mg. The molecular weight and isoelectric point of the purified enzyme were 54,000 and pI 5.4, respectively. The optimal pH and temperature were 6.0 and $45^{\circ}C$, and the enzyme was stable between pH 6.5 and 7.5 and below $50^{\circ}C$. The estimated Km and Vmax were 10 mg/mL and $6.25{\mu}mol/min$ for carboxymethyl cellulose and 30.3 mg/mL and $2.85{\mu}mol/min$ for sigmacell, respectively. The enzyme was partially inhibited by $Ag^+$, $Zn^{+{+}}$, $Fe^{+{+}}$ and EDTA, while completely inhibited by $Cd^{+{+}}$ and $Hg^{+{+}}$ at 1 mM concentration.
섬유소분해세균 Cellulomonas sp. CS1-1을 미소결정성 섬유소(sigmacell)에서 배양하면서 생육 및 1,4-${\beta}$-glucanase의 생산량을 조사하였다. 생균수는 배양 1일만에 최대이었지만 1,4-${\beta}$-glucanase의 활성도는 CMC 당화력으로 280 units/mL, 점도저하력으로 $3{\times}10^3units/mL$으로서 배양 5일째 최대이었으며, 이것은 가용성기질에 비하여 약 3배 높은 수준이었다. 또한 배양여액으로 부터 황산암모늄침전, Ultro-gel Ac54 겔여과, DEAE-Sephadex A50 이온교환크로마토그래피, 그리고 Con A-Sepharose 4B 친화성크로마토그래피의 방법으로 CMCase의 한분획을 순수정제하였다, 정제한 CMCase는 8.2%의 탄수화물을 함유하는 당단백질이었으며 그 정제도는 배양여액에 비해 CMC 당화력으로 22배 증가한 것이었다. 분자량은 54,000 그리고 둥전점은 pI 5.4 이었으며, 작용최적 pH 및 온도는 각각 pH 6.0 과 $45^{\circ}C$ 이었다. 정제효소의 CMC에 대한 Michaelis 상수 및 최대반응속도는 10 mg/mL, $6.25{\mu}mol/min$, 그리고 sigmacell에 대해서는 각각 30.3 mg/mL, $2.85{\mu}mol/min$으로 계산되었다 효소의 활성도는 $Ag^+$, $Zn^{+{+}}$, $Fe^{+{+}}$ 그리고 EDTA에 의해 부분적으로 저해되었고, 1mM의 $Cd^{+{+}}$와 $Hg^{+{+}}$ 이온에 의해서는 완전히 저해되었다.
(Department of Agricultural Chemistry, Chungnam National University)
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