The multimeric structure and disulfide‐bonding pattern of bovine κ‐casein

Bovine κ‐casein was analyzed by SDS/PAGE, MS and amino acid sequence analysis in order to determine its multimeric composition and disulfide‐bonding pattern. SDS/PAGE revealed that κ‐casein in the native state can range in size from a monomer to a multimeric structure larger than a decamer. Three types of interchain disulfide linkage, Cys11–Cys11, Cys11–Cys88 and Cys88–Cys88, were all assigned in multimers purified from [¹⁴C]carboxymethylated and untreated bulk milk, as well as a milk sample from a κ‐casein‐variant‐B homozygote Co20. These results indicate that multimerization occurs in a random or at present unpredictable disulfide‐bonding pattern regardless of the size of the multimer or the genotype.