PURIFICATION AND SOME PROPERTIES OF AN ALKALINE XYLANASE FROM ALKALIPHILIC BACILLUS SP STRAIN-41M-1

An alkaliphilic Bacillus sp. strain, 41M-1, isolated from soil produce d multiple xylanases extracellularly. One of these xylanases was purif ied to homogeneity by ammonium sulfate fractionation and anion-exchang e chromatography. The molecular mass of this enzyme (xylanase J) was 3 6 kDa, and the isoelectric point was pH 5.3. Xylanase J was most activ e at pH 9.0. The optimum temperature for the activity at pH 9.0 was ar ound 50-degrees-C. The enzyme was stable up to 55-degrees-C at pH 9.0 for 30 min. Xylanase J was completely inhibited by the Hg2+ ion and N- bromosuccinimide. The predominant products of xylan hydrolysate were x ylobiose, xylotriose, and higher oligosaccharides, indicating that the enzyme was an endoxylanase. The apparent K(m) and V(max) values on xy lan were 3.3 mg/ml and 1,100 mumol min-1 mg-1, respectively. Xylanase J showed high sequence homology with the xylanases from Bacillus pumil us and Clostridium acetobutylicum in the N-terminal region. Xylanase J acted on neither crystalline cellulose nor carboxymethyl cellulose, i ndicating a possible application of the enzyme in biobleaching process es.