Fractionation of bovine whey proteins and characterisation by proteomic techniques

To further elucidate and understand bovine milk protein composition and its relation to bioactivity, we have investigated the bovine whey proteome by gel-based proteomic methods, after first fractionating whey from late-lactation milk into acidic, basic and non-bound fractions by semi-coupled anion and cation exchange chromatography. Characteristic two-dimensional gel fingerprints were obtained for each fraction, with protein isoform patterns clearly apparent. A large number of minor whey proteins were identified, several of which have not been reported previously in bovine milk. Notably, a cluster of osteopontin peptides not priorly described in milk was consistently observed in the acidic protein fraction, presupposing novel bioactivities.