Isolation of Canine αs-Casein and Major Whey Protein Component A and Their Amino Acid Composition

Abstract

Canine whole casein shows two strong bands designated “Canine αs- and β-casein” corresponding to bovine αs- and β-casein on gel electrophoresis, but both αs- and β-casein have lower mobilities than bovine counterparts. Canine αs-casein was isolated by column chromatography on DEAE cellulose, whereas canine β-casein fraction was isolated by urea fractionation. Phosphorus content and calcium sensitivity of the canine αs-casein and β-casein fraction resemble those of bovine αs- and β-casein, espectively. Canine αs-casein contains more arginine and less serine, glycine, methionine and lysine. Canine β-casein fraction has a high nonpolar amino acid as bovine β-casein, but it is low in glycine and tryptophan. Canine whey protein has five major bands on gel electrophoresis. Major Component A, the fastest moving band has greater mobility than bovine β-lactoglobulin. Component A was isolated by salt fractionation and by column chromatography on DEAE cellulose. Amino acid composition of Component A resembles that of bovine β-lactoglobulin, with less lysine and more arginine in the former. Also it resembles that of porcine β-lactoglobulin, with less serine and lysine and more tyrosine and tryptophan in the former. © 1972, American Dairy Science Association. All rights reserved.