CM Sephadex C-25 column chromatography of Naja. naja venom. Elution profile of N. naja venom, 600 mg of Naja. naja venom, equivalent to 580 mg of protein, in 20 mM phosphate buffer, pH7.0 fractionated on CM-Sephadex C-25 column (1.6×135 cm), fractions eluted in step wise manner using phosphate buffer of different molarities (0.02–0.3 M) and pH values (7.0–8.0). Fractions collected at flow rate of 1.5 ml/5 min, monitored at 280 nm. Peak XI chosen for further purification.