Identification of the κ-Casein Among the Components of Whole Goat Casein

作者：Charles A. Zittle, Jonathan H. Custer · 发表于：Journal of Dairy Science · 年份：1966 · DOI：10.3168/jds.s0022-0302(66)87946-8 · 被引用次数：28 · 研究领域：Proteins in Food Systems、Protein Hydrolysis and Bioactive Peptides、Enzyme Production and Characterization

Goat ,-casein in the reduced state, probably the natural state, has a mobility on acrylamide gel electrophoresis at pH 9, very close to that of the fi-easeins.The goat K-casein was identified by clotting with rennin, by specific changes in the electrophoretic pattern after rennin action, and by nonpreeipitation with calcium ions.It stabilized goat a,-casein so that a~-casein was not precipitated with calcium ions.PolyaczTlamide gel electrophoresis of goat K-casein in some cases gave a single band (together with identifiable contaminants), and, in other cases, gave a multiplicity of slower-moving bands.In all cases only a single major band was observed when the ~-casein was reduced with mereaptoethanol.Components with the mobilities of para-Kcasein were present in considerable amounts in some preparations of ~-casein.Goat casein is characterized by two strong bands in the fl-casein region ~ on gel electrophoresis at pH 9. On treating whole goat casein with urea-sulfuric acid for the isolation of u-casein (11), preparations were obtained that on eleetrophoresis gave a principal band moving in the fi-casein region.Other preparations on electrophoresis gave multiple slower-moving bands, but these preparations, too, gave a principal band moving in the fl-easein region when treated with mereaptoethanol for electrophoresis.This paper will show that the preparations obtained by the urea-sulfuric acid method are indeed K-casein and will report some interesting properties of goat u-cas...