title: Lipoprotein-X: a substrate for lecithin: cholesterol acyltransferase.
abstract: The action of lecithin:cholesterol acyltransferase (LCAT) was studied on an abnormal lipoprotein (LP-X) rich in phosphatidylcholine and cholesterol from the plasma of patients with obstructive liver disease. 60 mg LP-X isolated free of other lipoproteins and subsequently labelled with 3H-cholesterol were incubated with 1 mg highly purified enzyme in the presence of albumin. After 45 h at 37 degrees C, the incubation mixture was subjected to zonal ultracentrifugation. 3H-cholesterol and 3H-cholesteryl esters were quantified in each fraction of the zonal gradient. More than 95% of the lipoproteins in this mixture banded in the density range of LP-X with no change in size distribution, but did contain 593 nmoles of newly formed cholesteryl esters. Agarose electrophoresis revealed an alpha-migrating band in addition to the original beta-band. Also on agar, the typically cathode migrating LP-X was changed to anode moving material. These studies indicate that LP-X can serve as a substrate for LCAT.
mesh_terms: D000217:Acyltransferases / Q000097:blood*; D002779:Cholestasis / Q000201:enzymology*; D002788:Cholesterol Esters / Q000096:biosynthesis; D002850:Chromatography, Gel; D004796:Clinical Enzyme Tests; D004587:Electrophoresis, Agar Gel; D006801:Humans; D066298:In Vitro Techniques; D007553:Isotope Labeling; D008077:Lipoproteins, LDL / Q000097:blood*; D007862:Phosphatidylcholine-Sterol O-Acyltransferase / Q000097:blood*; D014316:Tritium
chemical_list: D002788:Cholesterol Esters; D008077:Lipoproteins, LDL; D014316:Tritium; D000217:Acyltransferases; D007862:Phosphatidylcholine-Sterol O-Acyltransferase