Analysis of major ovine milk proteins by reversed-phase high-performance liquid chromatography and flow injection analysis with electrospray ionization mass spectrometry

Ovine milk proteins were analyzed both by coupling HPLC and electrospray ionization mass spectrometry (ESI-MS) and by flow injection analysis and ESI-MS detection after separation and collection of fractions from gel permeation chromatography. These methods resolved the four ovine caseins and whey proteins and made it possible to study the complexity of these proteins associated with genetic polymorphism, post-translational changes (phosphorylation and glycosylation) and the presence of multiple forms of proteins. The experimental molecular masses of ewe milk proteins were: 19 373 for κ-casein 3P; 25 616 for αs2-casein 10P; 23 411 for αs1-casein C-8P; 23 750 for β-casein 5P; 18 170 and 18 148 for β-lactoglobulins A and B; 14 152 for α-lactalbumin A and 66 322 for serum albumin.