Interaction of human plasma high density lipoprotein HDL2 with synthetic saturated phosphatidylcholines

The interaction of human plasma high density lipoprotein HDL2 (d 1.063-1.125 g/ml) with sonicated dispersions of synthetic saturated phosphatidylcholines, dipalmitoyl- (diC16PC), dimyristoyl- (diC14PC), didodecanoyl- (diC12c), didecanoyl- (diC10PC), and dioctanoyl- (diC8PC) L-alpha phosphatidylcholine, was investigated. Incubation (4.5 hr, 37 C) of HDL2 with diC14PC, diC12PC, diC10PC and diC8PC followed by gradient gel electrophoresis of preparative ultracentrifugation resulted in a redistribution of apolipoprotein A-I (apoA-I). The extent of redistribution depended on the molar ratio of the phospholipid to HDL2 in the incubation mixture. Redistributed apoA-I occurred as lipid-free apoA-I and/or as complexes of apoA-I and/or as compelxes of apoA-I with phosphatidylcholine. Increasing the length of time of ultracentrifugation of the interaction mixtures did not increase the extent of redistribution. No redistribution of apoA-I was detected following incubation and gradient gel electrophoresis or preparative ultracentrifugation of mixtures of HDL2 with dispersions of diC16PC.