Solubilization and characterization of apolipoprotein B from human serum low-density lipoprotein in n-dodecyl octaethylene glycol monoether.

Apolipoprotein B, the core polypeptide of human serum low-density lipoprotein, retains its native association state (500 000 g/complex), as well as its native conformation as judged by circular dichroism, when all lipid has been replaced by a nonionic detergent. Protein solubilized in this detergent should therefore be well suited for lipid binding studies. The native association state is also preserved when lipid is replaced by ionic detergents, but in this case the protein undergoes a conformational change, which can be reversed if the ionic detergent is replaced by nonionic detergent. The constancy of the state of association of the B polypeptide in a variety of amphiphilic environments contrasts with what has been observed with polypeptides from high-density lipoproteins which exist in different states of association under different conditions.