The action of a bacterial acyltransferase similar in overall reaction mechanism to the plasma enzyme lecithin:cholesterol acyltransferase (LCAT) has been studied using normal plasma and lipoproteins and plasma from LCAT-deficient patients. The microbial enzyme (GCAT) catalyzed acyl transfer using phosphatidylcholine and cholesterol in all of the lipoprotein fractions, presumably because it has ...

Natural abundance 13C NMR spectroscopy at 63.4 kG was used to probe the temperature dependence of lipid dynamics in low density lipoproteins (LDL) and in aortic fibrous plaques (i&ma-media sections). Spectra of LDL from normals and a familial type II were essentially indistinguishable. At 37”C, tissue spectra exhibit numerous narrow fatty acid and cholesteryl ester ring resonances, no peaks att...

High resolution proton-decoupled natural abundance ‘:‘C NMR spectra (at 15.18 MHz) of human plasma high density lipoproteins were recorded at 29”C, Yfi”C, and 43°C. Carbon 5 of unesterified cholesterol and the corresponding carbon of cholesteryl esters yield narrow, well resolved resonances. Values of nuclear Overhauser enhancements and integrated intensities for C-5 of free and esterified chol...

Rabbits fed low-fat, cholesterol-free diets containing casein as the sole protein source develop endogenous hypercholesterolemia (EH). To test the hypothesis that lipoprotein cholesteryl esters in EH rabbits are acyl coenzyme A:cholesterol acyltransferase (ACAT) derived, we treated EH rabbits with CI-976, a potent and selective ACAT inhibitor. In addition, since cholesterol and bile acid synthe...

The rate of uptake of cholesteryl ester from chylomicrons has been determined with the isolated perfused rat heart and both intact and functionally hepatectomized rats. Uptake was found to be proportional to the cholesteryl ester content of the particles. Transfer of cholesteryl ester to other lipoprotein classes of the plasma was negligible under these conditions, and loss of cholesteryl ester...

Spheroidal high-density lipoprotein (HDL) particles circulating in the blood are formed through an enzymatic process activated by apoA-I, leading to the esterification of cholesterol, which creates a hydrophobic core of cholesteryl ester molecules in the middle of the discoidal phospholipid bilayer. In this study, we investigated the conformation of apoA-I in model spheroidal HDL (ms-HDL) parti...

The intravascular metabolism of the cholesteryl ester moiety of rat plasma LDL, HDL1, and HDL2 was determined in intact male rats. Biosynthetically labeled lipoproteins were prepared by zonal ultracentrifugation from the plasma of rats injected with [3H]cholesterol. The lipoproteins were concentrated by vacuum ultrafiltration as other procedures were found to alter the biological properties of ...

We have previously observed that cholesterol-fed dogs with plasma cholesterol levels of 350 to 750 mg/dl failed to develop atherosclerosis (hyporesponders), whereas cholesterol-fed dogs with cholesterol levels greater than 750 mg/dl developed markedly accelerated atherosclerosis (hyperresponders). Two striking features of the hypercholesterolemia of the hyperresponders were the occurrence of ch...

The oxidative modification of low-density lipoprotein (LDL) has been implicated as a pro-atherogenic process in the pathogenesis of atherosclerosis. Macrophages rapidly take up oxidized LDL via scavenger-receptor-mediated pathways and thereby develop into lipid-laden foam cells. The uptake mechanism has been studied extensively and several types of scavenger receptors have been identified. In c...

Cholesteryl sulfate is a normal constituent of human spermatozoa. The in vitro uptake of tritiated cholesteryl sulfate resulted in the labeling of all spermatozoa as demonstrated by light-microscope radioautography. The binding of the sterol sulfate was localized mainly in the head and midpiece. Radioautography at the level of the electron microscope revealed that the sterol sulfate is localize...