The extracellular xylanase from the crude culture filtration of Bacillus pumilus A 30 was purified by ammonium sulfate fractionation,CM Sephadex C 50,DEAE Sephadex A 50 and Bio gel P 30 chromatographies.SDS PAGE analysis indicated that the xylanase had molecular weight 23 kD.Its isoelectric point p I 8.5 was determined by IEF PAGE.Its temperature optima for the activity and its optimum pH was 50℃ and 7.5 respectively.It was stable in a broad pH range and showed good stability below 50℃。Its activity was strongly inhibited by Ag +,Cu 2+ ,Fe 3+ ,Co 2+ ,Hg 2+ ,Zn 2+ ,Al 3+ and increased dramatically by Mg 2+ ,Ca 2+ .Its K m and V m were 7.42 mg·ml -1 and 654 μmol·min -1 ·mg -1 respectively.
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