Purification of goats' milk casein by reversed-phase high-performance liquid chromatography and identification of αs1-casein

Abstract

Summary: Goats’ milk caseins were separated into four components in a single run using reversed-phase gradient high-performance liquid chromatography. The purity of the isolated components was checked by sodium dodecyl sulphate polyacrylamide gel electrophoresis, amino acid analysis and determination of the N-terminal residue. By a comparison with previously published results for goats’ milk caseins the four peaks were identified as κ-, α_s1-, α_s2- and β-casein. In order to confirm the existence of α_sl-casein in goats’ milk, this component was sequenced for 44 steps, revealing a sequence homologous to bovine α_sl-casein and almost identical to the N-terminal sequence previously published by Boulangeret al.(1984).