Study of the apoprotein of Folch-Pi bovine proteolipid. II. Characterization of the components isolated from sodium dodecyl sulfate solutions.

Acrylamide gel electrophoresis in dodecyl sulfate solutions of Folch-Pi apoprotein shows several bands. The different components were separated by Biogel P-200 filtration and then reduced and carboxymethylated. A comparative study of the amino acid composition, N-terminal sequence and C-terminal amino acid of the different components led to the assumption that their primary sequences are similar. Evidence for a contamination of the protein by free amino acids might explain the difference in terminal groups found by us and by other groups. It has been shown that the purified components can polymerize independently of S-S bond formation or exchange. The polymerization products were found to resist dissociation by dodecyl sulfate. It has been suggested therefore that the differences in migration rates of the various components are related to their shape rather than to their molecular weight.