Syncephalastrum racemosum Cohn. produces an extracellular xylanase that was shown to potentially bleach pulp at pH 10 and 50°C. The enzyme was found to be a dimer with an apparent molecular weight of 29 kDa as determined by SDS-PAGE. The optimum activity was found at two pH values 8.5 and 10.5; however the activity sharply decreased below pH 6 and above pH 10.5. The enzyme was stable for 72 h at pH 10.5 and at 50°C. Kinetic experiments at 50°C gave V max and K m of 1,400 U/ml min ؊1 mg ؊1

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... n and 0.05 mg/ml respectively. The enzyme had no apparent requirement for cofactors, and its activity was strongly inhibited by group II b metal ions like Zn 2؉ , Hg 2؉ , etc. Xylan completely protected the enzyme from being inactivated by N-bromosuccinimide.