Purification of disulphide-linked alpha s2- and kappa-casein from bovine milk.
Naturally occurring disulphide-linked alpha s2- and kappa-casein in bovine milk were purified by gel chromatography on a column of Sepharose CL-6B. Four fractions (A-D) were obtained by elution with ammonium acetate-urea buffer. Fractions A and B, identified by SDS gel electrophoresis and amino acid sequence analysis, corresponded to disulphide-linked kappa-casein and alpha s2-casein respectively. Fraction C consisted of a mixture of alpha s1-, alpha s2-, and beta-casein. Separation of fraction C into its components was achieved by reversed-phase HPLC. The stability of the disulphide bridges in alpha s2- and kappa-casein was shown to differ with respect to reducing agents (dithioerythritol and 2-mercaptoethanol).
Rasmussen
L K
LK
MD Foods Research and Development Centre, Roerdrumvej, Denmark.
Petersen
T E
TE
D000595:Amino Acid Sequence; D000818:Animals; D002364:Caseins / Q000737:chemistry / Q000302:isolation & purification*; D002417:Cattle; D005591:Chemical Fractionation; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004220:Disulfides / Q000737:chemistry*; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D008892:Milk / Q000737:chemistry*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D012044:Regression Analysis
D002364:Caseins; D004220:Disulfides