IMMUNOREACTIVITY OF GOATS MILK CASEIN FRACTIONATED BY ION-EXCHANGE CHROMATOGRAPHY

Goat's milk casein was fractionated by anion-exchange fast protein liq uid chromatography (FPLC) on a Mono and HR 5/5 column and by cation-ex change chromatography on a column containing an S-Sepharose Fast Flow matrix. The identification of the resulting fractions was performed by SDS-PAGE using a PhastSystem electrophoresis unit. Three fractions (b eta-casein, kappa-casein, and alpha(s)-casein) were separated by anion -exchange FPLC, while cation-exchange chromatography allowed the ident ification of four fractions (beta-casein, kappa-casein, alpha(s1)-case in, and alpha(s)-casein). The purified fractions were characterized im munologically by an indirect ELISA using polyclonal antibodies raised in rabbits against goat's casein and further purified by affinity chro matography in a column containing immobilized goat's caseins, biotinyl ated and blocked with lyophilized ovine and bovine caseins. The most i mmunoreactive caprine casein fraction was the alpha(s2)-casein purifie d by cation-exchange chromatography, meaning this is the fraction with the largest number of epitopes specific of goat's milk casein.