ISOLATION AND PARTIAL CHARACTERIZATION OF POLYPEPTIDE CHAINS IN HUMAN CERULOPLASMIN

The polypeptide-chain structure of human ceruloplasmin has been investigated. Two different polypeptide chains, α and β, were isolated from reduced and aminoethylated ceruloplasmin either by gel filtration in 5.5 M guanidine or by preparative polyacrylamide column electrophoresis at pH 10.3 in 8 M urea. The α chain had a molecular weight of 15 900 and had valine as its N-terminal amino acid. It was antigenically different from the β chain. The β chain was heterogeneous. Two β chains, β′ and β″, could be isolated by the preparative electrophoresis method. Both of the β chains had lysine as their N-terminal amino acid and had the same elution volume on gel filtration. The molecular weight of the β″ chain was found to be 58 900. The β chains were antigenically partially identical. © 1969.