Purification of lactoperoxidase from bovine milk by integrating the technique of salting-out extraction with cation exchange chromatographic separation

Abstract

In the current experiment, the integrated techniques of salting-out extraction followed by cation exchange chromatographic separation were used to purify lactoperoxidase (LP) from milk whey. In order to optimize the purification condition of LP, the different conditions of salting out extraction as well as chromatographic separation were tried and the efficiency of these conditions were evaluated in terms of activity recovery and purification fold. LP extracted with ammonium sulphate for 8 h at pH 6.5, followed by centrifugation at 7000 rpm was revealed as optimum salting condition due to maximum value activity recovery (85.74%) and purification fold (3.13%). LP from this optimum salting out extraction process were furthermore separated in 100 GigaCap S-650M strong cation chromatographic column (20 cm × 1.6 cm, 50–100 µm) by using phosphate buffer (0.03M, pH 7.2) with flow rate of 2 mL/min which was shown highest activity recovery (82.62%) and purification fold (126.65 times). It was also verified that there was a single band presence and the molecular weight of LP was approximately 85 kDa by SDS-PAGE analysis. Therefore, it is suggested that combination of salting-out and GigaCap S-650M strong cation exchange chromatography could be an efficient and practical method to purify bovine LP.