Rapid purification of human plasma lipid transfer proteins.

Lipid transfer protein (LTP) was isolated from human plasma after lipoproteins were removed by precipitation with dextran sulfate. Three sequential chromatogrpahic procedures were used: butyl-Toyopearl 650, CM-Toyopearl 650, and Toyopearl HW-55. The entire procedure required only a few days and purification was as high as 43,000-fold from the lipoprotein-depleted plasma with the yield of 30%. The final preparation contained two bands on sodium dodecylsulfate electrophoresis; the major and minor components had apparent molecular weights of 69,000 and 66,000, respectively. Both bands catalyzed the transfer of cholesteryl ester with the same specific activity, and had the same N-terminal amino acid sequence. Stabilization of the lipid emulsions with apolipoprotein A-I enhanced the LTP-catalyzed transfer of cholesteryl ester from low density lipoprotein with the reciprocal transfer of triglyceride in a manner similar to that previously observed with partially purified LTP (Nishikawa, O., S. Yokoyama, H. Okabe, and A. Yamamoto. 1988. J. Biochem. 103: 188-194).