Enzymatic Properties of Cellobiohydrolase immobilized in Soil

토양내에 고정화되어 있는 Cellobiohydrolase의 효소학적 성질

The enzymatic properties of soil cellobiohydrolase were examined and compared with those of cellobiohydrolase-active extracts from soil in the forms of enzyme-humic complex and humicfree enzyme, and cellobiohydrolase partially pruified from Aspergillus niger. The pH optima of soil cellobiohydrolase and cellobiohydrolase-humic complex were greater by 1.5-3.0 pH units than those of cellobiohydrolase in humic-free extract and from A. niger. Soil cellobiohydrolase and cellobiohydrolase-humic complex were remarkably resistant to thermal denaturation and proteolysis. These results confirm that cellobiohydrolase in soil is atable in conditions which rapidly inactivate microbial cellobiohydrolase and that its stability is due to the immobilization of this enzyme by association with humic substances. The Michaelis-Menten constants (Km) for soil, cellobiohydrolase-humic complex, humic free extract and cellobiohydrolase from A. niger were 22.1mg/ml, 11.3mg/ml, 10.6mg/ml and 4.5 mg/ml of Avicel, respectively.