2.4. Enzyme purification and assayThe culture supernatant was supplemented with solid ammonium sulphate to 65% (w/v) final concentration, with mechanicalstirring at 4 C. The suspension was retained for 1 h at 4 C, andcentrifuged at 8000 rpm for 30 min at the same temperature. Theresultant supernatant was brought to 70% w/v ammoniumsulphate saturation at 4 C. 50–70% (w/v) ammonium sulphateprecipitate was recovered, dissolved in 0.1 M phosphate buffer