PURIFICATION AND CHARACTERIZATION OF 2 PORCINE BETA-LACTOGLOBULIN VARIANTS BY NACL SALTING-OUT AND REVERSED PHASE-HPLC

Porcine whey proteins have been separated by reversed-phase HPLC and the different eluted fractions were analysed by SDS-PAGE. Two protein fractions lately eluted from HPLC, with an apparent molecular weight of approximately 18 800 had an amino acid composition corresponding to that of porcine beta-lactoglobulin, These 2 fractions differed only in their Ala/Val content and consequently may be genetic variants of porcine beta-lactoglobulin. In order to obtain larger amounts of beta-lactoglobulin, we attempted to adapt to porcine whey a previously published method used for bovine beta-lactoglobulin and based on NaCl salting-out at low pH. Each step of purification was monitored by RP-HPLC. After precipitation (14% NaCl), solubilisation in 7% NaCl and dialysis against distilled water, beta-lactoglobulin was obtained with a purity of 94%. Final separation of beta-lactoglobulin variants can be rapidly achieved by RP-HPLC on a semi-preparative column.