Mechanism of heparin and serum lipoprotein interaction: Effects of calcium, phosphorylcholine, and a serum fraction

1978 ◽  
Vol 56 (7) ◽  
pp. 746-752 ◽  
Author(s):  
Sailen Mookerjea
Keyword(s):  
Serum Lipoprotein ◽  
Low Density Lipoproteins ◽  
Precipitation Reaction ◽  
Low Density ◽  
Mechanism Of Formation ◽  
Very Low Density Lipoproteins ◽  
Rat Serum ◽  
Protein Factor ◽  
Insoluble Complex ◽  
Lipoprotein Complex

The mechanism of formation of an insoluble complex between heparin and rat serum lipoprotein has been studied. Optical density changes during the reaction, counting of the fatty acid labelled lipoproteins in the precipitates, and complexing of [14C]palmitate-labelled lipoprotein with heparin–CNBr–Sepharose were used to quantitatively determine the formation of insoluble complexes. The maximal heparin–lipoprotein complex formation requires 25–30 mM of Ca2+, but with micromolar amounts of phosphorylcholine, the reaction was saturated at only 10 mM of Ca2+. The effect of phosphorylcholine in promoting the reaction was lost when purified chylomicrons or very low density lipoproteins were used. The effect of phosphorylcholine in promoting the interaction between heparin and pure chylomicrons or very low density lipoproteins was regained when a crude serum protein factor of unwashed chylomicrons was added to the system, suggesting that rat serum contains a protein factor(s) which normally inhibits the heparin–lipoprotein interaction by raising the requirement for Ca2+. Phosphorylcholine counteracted the effect of this protein, thereby favouring the precipitation reaction in the presence of much lower concentration of Ca2+. The results have been discussed with special reference to the possibility of a relationship between mucopolysaccharides, Ca2+, lipoproteins, and arterial phospholipids in the pathogenesis of atherosclerosis.

The levels of apolipoprotein-E in hypercholesteroiemic rat serum

1978 ◽  
Vol 56 (3) ◽  
pp. 161-166 ◽  
Author(s):  
Laurence Wong ◽  
David Rubinstein
Keyword(s):  
Golgi Apparatus ◽  
Apolipoprotein E ◽  
Fold Increase ◽  
Low Density Lipoproteins ◽  
Low Density ◽  
Very Low Density Lipoproteins ◽  
Rat Serum ◽  
Apo E ◽  
Control Serum ◽  
Lipoprotein Complex

The levels of apolipoprotein-E (apo-E) in serum and isolated lipoproteins from diet-induced hypercholesterolemic, and to some extent, hypertriglycerdemic rats were measured by electroimmunoassay. The hypocholesterolemia was accompanied by a mild hypertriglyceridemia. The apo-E was increased by 60% in the hypercholesterolemic serum with a 5- and 50-fold increase in very low density lipoproteins (VLDL) and low density lipoproteins (LDL) respectively. However, the proportion of apo-E in nascent VLDL isolated from the hepatic Golgi apparatus of hypercholesterolemic rats was significantly decreased. In control serum, 40–50% of the apo-E is found in the density >1.21 g/ml fraction, although this is at least partially due to ultracentrifugation. The aproprotein is absent from the density >1.21 g/ml fraction from hypercholesterolemic serum, suggesting that it is bound more firmly to the lipoprotein complex. It is concluded that the large increases in apo-E in the VLDL and LDL density ranges of serum from hypercholesterolemic rats may in part be accounted for by the utilization of apo-E normally found at higher densities.

Removal rates of rat serum [3H] labeled very low density lipoproteins after consumption of two different low protein diets

1991 ◽  
Vol 11 (6) ◽  
pp. 587-597 ◽  
Author(s):  
Malika Meghelli-Bouchenak ◽  
J. Belleville ◽  
M. Boquillon ◽  
B. Scherrer ◽  
J. Prost
Keyword(s):  
Low Density Lipoproteins ◽  
Low Density ◽  
Very Low Density Lipoproteins ◽  
Removal Rates ◽  
Rat Serum ◽  
Low Protein ◽  
Protein Diets

Improved Techniques for Assessment of Serum Lipoprotein Patterns. II. Rapid Method for Diagnosis of Type III Hyperlipoproteinemia without Ultracentrifugation

1973 ◽  
Vol 19 (10) ◽  
pp. 1139-1141 ◽  
Author(s):  
Heinrich Wieland ◽  
Dietrich Seidel
Keyword(s):  
Rapid Method ◽  
Serum Lipoprotein ◽  
Low Density Lipoproteins ◽  
Plasma Lipoproteins ◽  
Agarose Gel ◽  
Low Density ◽  
Electrophoretic Separation ◽  
Very Low Density Lipoproteins ◽  
Type Iii ◽  
Type Iii Hyperlipoproteinemia

Abstract Based on the previously described technique [Clin. Chem.19, 737 (1973)] of precipitating plasma lipoproteins with polyanions after their electrophoretic separation in gels, a new method is presented for diagnosing type III hyperlipoproteinemia without need for ultracentrifugation or immunologic techniques. Used in the procedure are 0.1 mol/liter MgCl2, 1.5 g/liter heparin, and 10 g/liter NaCl to visualize selectively the very-low-density lipoproteins in agarose gel after electrophoresis. The technique is simple, inexpensive, accessible to every laboratory, and provides the answer in less than 2 h after electrophoresis of the patient’s whole serum. The results obtained are the same as those obtained by ultracentrifugation followed by lipoprotein electrophoresis of the isolated fractions.

A comparison of some immunological characteristics of very low density lipoproteins of normal and hypercholesterolemic rat sera

1978 ◽  
Vol 56 (6) ◽  
pp. 673-683 ◽  
Author(s):  
Peter J. Dolphin ◽  
Laurence Wong ◽  
David Rubinstein
Keyword(s):  
Polyacrylamide Gel Electrophoresis ◽  
Normal Serum ◽  
Low Density Lipoproteins ◽  
High Density Lipoproteins ◽  
Low Density ◽  
Very Low Density Lipoproteins ◽  
Rat Serum ◽  
Apo B ◽  
Apo E

The immunological characteristics of very low density lipoproteins (VLDL) from normal and hypercholesterolemic rat sera were compared using polyspecific antisera to VLDL and high density lipoproteins (HDL) and monospecific antisera to apo-B, apo-C, apo-A-I, and apo-E. Ultracentrifugally isolated VLDL from normal serum were studied by immunodiffusion and found to contain both discrete and associated (with apo-B) apo-C and apo-E, probably in the form of lipid-containing lipoproteins. However, immunoelectrophoresis of whole serum revealed only an associated form of the lipoprotein having pre-β mobility (i.e., VLDL), suggesting that the presence of discrete lipoproteins in isolated VLDL, each containing a single apoprotein family, may represent ultracentrifugal artifacts. Ultracentrifugally isolated VLDL from diet-induced hypercholesterolemic rat serum contained only trace amounts of apo-C and large quantities of apo-E, both of which were totally associated with apo-B. VLDL isolated by ultracentrifugation from perfusate of normal and hypercholesterolemic livers contained only associated lipoprotein complexes made up of apo-B, apo-C, and apo-E in the former but only apo-B and apo-E in the latter. These data suggest that normal VLDL are secreted as lipoprotein complexes containing apo-B, apo-C, and apo-E which may become destabilized in the circulation. However, VLDL from hypercholesterolemic serum show a marked diminution in the quantity of apo-C as indicated by the relative incorporation of [3H]leucine in vivo and by polyacrylamide gel electrophoresis of apo-VLDL.

The catabolism of very low density lipoproteins

1985 ◽  
Vol 63 (8) ◽  
pp. 890-897 ◽  
Author(s):  
W. Carl Breckenridge
Keyword(s):  
Surface Composition ◽  
Hepatic Lipase ◽  
Low Density Lipoproteins ◽  
Low Density ◽  
Core Particle ◽  
Mechanism Of Formation ◽  
Very Low Density Lipoproteins ◽  
Apo E

The lipolysis of very low density lipoproteins (VLDL) in vitro is a useful model for the study of the process of conversion of this triacylglycerol rich lipoprotein into low (LDL) and high (HDL) density lipoproteins. Data is reviewed to show that a portion of surface cholesterol and phospholipid which becomes redundant during lipolysis is lost from the lipoprotein. In the absence of HDL, the material forms lipoprotein-X (LpX) like vesicles which are not readily disrupted by HDL once they are formed. In the presence of HDL during lipolysis, the material is largely incorporated into HDL. The data is used to suggest a mechanism of formation of LpX-like vesicles in conditions where the production of surface remnants exceeds the capacity of HDL to disrupt them. Evidence is also provided to show that apolipoproteins (apo) C-II, C-III, and E are lost from VLDL and that this loss is primarily in association with a neutral core particle of HDL size which can subsequently exchange lipids and apolipoproteins with plasma HDL. Such a mechanism could account for the removal of apo E and excess cholesteryl ester which is necessary for conversion of VLDL to LDL. The role of hepatic lipase in this process remains speculative. Recent evidence is reviewed and used to propose that the enzyme may serve to rearrange the neutral core and surface composition of LDL and HDL subfractions to allow for the packaging of cholesteryl esters and the cycling of apolipoproteins.

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