RESUMEN
The importance of cellulase as a means for the efficient utilization of abundant cellulose resources in the world has been well recognized. Many researchers devote themselves to studying the mechanism of the action of cellulase to cellulose so that such expensive enzyme can be used much more widely. The first step is to obtain cellulase of high purity. So purification of cellulase is the key point in this field. However, the major problem in isolation is that cellulase is a complicated enzyme system and needs too many steps for separation, and that every cellulase needs special purification processing which cannot be used for the others. A novel method for the separation of the cellulase from crude extraction of Aspergillus niger with normal qualitative filter paper processed by 5 mol/L sodium hydroxide without precipitation and desalting steps was developed. Further purification of the cellulase was achieved by using an anion-exchange column of POROS 20HQ. The cellulase purified was identified as a new endoglucanase that had relatively high endurance to pH and temperature. Its relative molecular mass was estimated to be 60,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This enzyme exhibited very high activity towards carboxymethyl cellulose (CMC) with specific activity of 350 U.mg-1 and the recovery of activity of 9.7%. Its optimum pH and temperature were 4.0 and 70 degrees C, respectively. This is a simple, rapid and efficient method for purifying cellulase with high activity.