Sulfhydryl chemistry and solubility properties of human plasma apolipoprotein B

Apolipoprotein B (apoB) was isolated from human plasma low-density lipoproteins (LDL; d = 1.02-1.05 g/mL) By delipidation with ether-ethanol, followed by solubilization of the protein with sodium decyl sulfate. Both intra-and intermolecular disulfide bonds impose modest restraints on the tertiary structure of apoB as determined by circular dichroism (CD) methods. Analysis of the far-UV CD region of apoB at various purification steps suggests that the conformation and state of association are the major factors contributing to the overall water solubility of apoB in the absence of denaturants and amphiphilic ligands.