The caseins of buffalo milk

Abstract

SummaryThe components of whole casein from water buffalo (Bubalis L.) have been re-investigated in the light of recent studies elucidating the primary structure of all the bovine caseins (αs1, αs2, β & κ). Whole casein samples obtained from individual Italian buffaloes all contained 2 αs1- and 2αs2-casein fractions. These 4 components were isolated and identified by their amino acid compositions and terminal amino acid sequences. The 2 αs1-casein fractions seem to have identical peptide chains as do the 2 αs2fractions, with the individual fractions within each group differing only in their phosphate content. Buffalo β-casein was also isolated and characterized by its amino acid composition and terminal sequences. The isolation of different buffalo κ-casein fractions was reported earlier (Addeo, Chobert & Ribadeau-Dumas, 1977). These fractions were purified and analysed. They were found to have the same amino acid compositions and C-terminal sequences, but to differ in their carbohydrate content. The prominent component, κ1, was treated with chymosin; the caseinomacropeptide and para κ-casein were separated from the digest and analysed. Starchgel electrophoresis at alkaline pH showed no polymorphism of αs1-, β- and κ-caseins in 170 individual buffalo whole casein samples. On 5 occasions the electrophoretic pattern of αs2-casein suggested genetic polymorphism. The behaviour of buffalo αs1−and αs2-caseins in the presence of Ca2+was also studied.