Studies on the fat emulsion Intralipid. I. Association of serum proteins to Intralipid triglyceride particles (ITP).

Intralipid triglyceride particles (ITP) were isolated by density gradient centrifugation. The isolated ITP fraction contained about 70% of the total triglycerides and 20% of the total phospholipids of the original Intralipid emulsion. Intralipid emulsion was mixed with equal parts of either albumin solution or VLDL-free serum and the ITP immediately isolated by centrifugation. The isolated ITP contained protein of which more than 90% disappeared upon recentrifugation in the case of albumin and only to 20% in the case of serum. It was demonstrated by polyacrylamide disc gel electrophoresis and double immunodiffusion with monovalent antisera against apolipoproteins that the proteins associated with ITP were mainly albumin; apolipoproteins CII and CIII in the two types of experiments respectively. The specific association of apolipoproteins CII and CIII to ITP offers an explanation to the chylomicron like metabolism of Intralipid in vivo.