electrophoresisSodium dodecyl sulphate-polyacrylamide gel electrophoresis(SDS-PAGE) was carried out as described by Laemmli (1970)using 5% (w/v) stacking and 15% (w/v) separating gels. Sampleswere prepared by mixing the crude enzyme extract at 1:5 (v/v)ratio with the SDS-PAGE sample buffer (10 mM glycine–NaOH(pH 10.0), 2.5% SDS, 10% glycerol, 5% -mercaptoethanol and0.002% bromophenol blue). Samples were heated at 100◦Cfor 5 min before loading in the gel. After electrophoresis, thegel was stained with 0.25% Coomassie Brilliant Blue R-250 in45% ethanol–10% acetic acid and destained with 5% ethanoland 7.5% acetic acid. The molecular mass marker (Sigma)used was: bovine serum albumin (66 kDa); ovalbumin (45 kDa);glyceraldehyde-3-dehydrogenase (36 kDa); bovine trypsinogen(24 kDa); soybean trypsin inhibitor (20.1 kDa) and bovine -lactoalbumin (14.2 kDa).