PURIFICATION AND CHARACTERIZATION OF 2 1,4-BETA-XYLAN ENDOHYDROLASES FROM THE RUMEN FUNGUS NEOCALLIMASTIX-FRONTALIS

Two beta-endoxylanases produced by Neocallimastix frontalis have been purified by ammonium sulfate precipitation, gel filtration, and ion-ex change chromatography. Xylanase I is a nonglycosylated protein with an apparent molecular mass of 45 kDa. Xylanase II is a glycoprotein with an apparent molecular mass of 70 kDa. The pH optima of these enzymes were 5.5 and 6, respectively, and the temperature optimum was 55-degre es-C for each enzyme. The endo mode of action of the enzymes was revea led by thin-layer chromatography of xylan hydrolysates. Antibodies rai sed against each purified protein exhibited no cross-reaction, confirm ing the biochemical specificities of the enzymes. Both enzymes exhibit ed carboxymethyl cellulase activity, and xylanase I was absorbed on cr ystalline cellulose, indicating that these enzymes might belong to the F family of beta-1,4-glycanases.