scholarly journals Phosphatidylcholine–cholesterol acyltransferase in the ultracentrifugal residual protein fraction of rat plasma

1971 ◽  
Vol 122 (4) ◽  
pp. 469-475 ◽  
Author(s):  
Michihiro Sugano
Keyword(s):  
Protein Fraction ◽  
Cholesterol Acyltransferase ◽  
Initial Step ◽  
Rat Plasma ◽  
Plasma Lipoproteins ◽  
Residual Fraction ◽  
Cholesterol Esters ◽  
General Properties ◽  
Residual Protein ◽  
Cholesteryl Linoleate

1. The phosphatidylcholine–cholesterol acyltransferase of rat plasma was dissociated from the plasma lipoproteins by ultracentrifugation and shown to be present in the plasma residual-protein fraction of density >1.210. 2. The general properties of the acyltransferase were substantially unchanged in the residual fraction as judged from the effects of differences in the substrates and of overnight starvation on the formation of different cholesterol esters. 3. The enzyme from rats starved overnight, by comparison with the enzyme from fed rats, preferentially formed cholesteryl arachidonate at the expense of cholesteryl linoleate. 4. The results suggest that ultracentrifugal separation of the plasma residual fraction may be used as an initial step for the purification of the acyltransferase.

STUDIES ON THE SYNTHESIS OF PLASMA GLYCOLIPOPROTEIN AND HEPATIC SUB-CELLULAR GLYCOPROTEIN IN EARLY CHOLINE DEFICIENCY

1967 ◽  
Vol 45 (6) ◽  
pp. 825-838 ◽  
Author(s):  
Sailen Mookerjea ◽  
David Jeng ◽  
Judith Black
Keyword(s):  
Liver Microsome ◽  
Specific Radioactivity ◽  
Plasma Lipoproteins ◽  
Residual Fraction ◽  
Choline Deficiency ◽  
Glycoprotein Synthesis ◽  
Limiting Step ◽  
Residual Protein ◽  
Lipoprotein Synthesis ◽  
Smooth Membrane

Impairment of glycoprotein synthesis in trichloroacetic acid insoluble and in residual protein (d > 1.21) fractions of plasma in early choline deficiency has been confirmed. Plasma lipoproteins of d < 1.006, 1.006–1.063, and 1.063–1.21 are also rapidly labelled after intraperitoneal injection of glucosamine-1-14C. In general, there was no difference in specific radioactivity of plasma glycolipoproteins between choline-supplemented rats and rats deprived of choline for 2 days during 180 min of incorporation.Incorporation of glucosamine-1-14C into microsomal glycoprotein is significantly impaired in early choline deficiency. Further sub-microsomal fractionation produced evidence that the site of impairment of glycoprotein synthesis is in the smooth microsome portion. These studies suggest that a decreased synthesis of glycoprotein(s) in liver-microsome smooth membrane and in the plasma residual fraction (d > 1.21) may represent an impairment of 'lipoprotein precursor protein' synthesis in early choline deficiency. An inhibition of this limiting step would possibly impair the rate of plasma lipoprotein synthesis, leading to the development of fatty liver in choline deficiency.

Modification of rat plasma lipoproteins induced by acute immobilization stress.

1994 ◽  
Vol 56 (6) ◽  
pp. 486-492 ◽  
Author(s):  
J C Ruiz de Gordoa ◽  
J Santafé ◽  
J Segarra Domenech ◽  
A Santisteban
Keyword(s):  
Immobilization Stress ◽  
Rat Plasma ◽  
Plasma Lipoproteins

Origin and Fate of Cholesterol in Rat Plasma Lipoproteins in vivo

1985 ◽  
Vol 29 (3) ◽  
pp. 160-174 ◽  
Author(s):  
T. Magot ◽  
G. Champarnaud ◽  
R. Anfreville ◽  
C. Lutton ◽  
F. Chevallier
Keyword(s):  
Rat Plasma ◽  
Plasma Lipoproteins

scholarly journals Hypocholesterolaemic effect of β β'-methyl-substituted hexadecanedioic acid (MEDICA 16) in the male hamster

1993 ◽  
Vol 289 (3) ◽  
pp. 911-917 ◽  
Author(s):  
N Mayorek ◽  
J Bar-Tana
Keyword(s):  
Cholesteryl Ester ◽  
Cholesterol Efflux ◽  
Free Cholesterol ◽  
Plasma Cholesterol ◽  
Cholesterol Acyltransferase ◽  
Cholesterol Content ◽  
Plasma Lipoproteins ◽  
Purina Chow ◽  
Apolipoprotein C ◽  
Bile Cholesterol

Treatment of cholesterol-fed male hamsters kept on a diet of purina chow with beta beta'-methyl-substituted hexadecanedioic acid (MEDICA 16) resulted in a progressive hypocholesterolaemic effect, amounting to a 50% decrease in the cholesterol content of all plasma lipoproteins. The decrease in plasma cholesterol could be accounted for by activation of plasma-cholesterol efflux through the liver into the bile mediated by MEDICA 16-induced (a) increase of the number of liver LDL receptors, (b) activation of liver neutral cholesteryl ester hydrolase with a concomitant inhibition of liver acyl-CoA cholesterol acyltransferase, resulting in shifting of the liver cholesteryl ester/free-cholesterol cycle in the direction of free cholesterol, and (c) activation of cholesterol efflux from the liver into the bile. The increase in bile cholesterol output was accompanied by an increase in bile phospholipids but not in bile acids. In contrast with rats, MEDICA 16-treatment of male hamsters did not result in a hypotriacylglycerolaemic effect, inhibition of lipogenesis, nor in a substantial decrease in plasma apolipoprotein C-III content.

scholarly journals IMMUNOCHEMICAL STUDIES ON HUMAN PLASMA LIPOPROTEINS

1957 ◽  
Vol 105 (1) ◽  
pp. 49-67 ◽  
Author(s):  
Frederick Aladjem ◽  
Miriam Lieberman ◽  
John W. Gofman
Keyword(s):  
Human Plasma ◽  
Plasma Protein ◽  
Protein Fraction ◽  
Low Density Lipoproteins ◽  
High Density ◽  
Plasma Lipoproteins ◽  
High Density Lipoproteins ◽  
Low Density ◽  
Plasma Protein Fraction ◽  
Free Plasma

Low density human plasma lipoproteins Sf 17+, Sf 13, and Sf 6, high density lipoproteins 2 and 3, and a lipoprotein-free plasma protein fraction were isolated from human plasma by ultracentrifugal methods. It was found that human plasma lipoproteins are immunochemically distinct from the non-lipoprotein containing plasma protein fraction. Lipoprotein fractions of a given hydrated density, isolated from different individuals, were found to be immunochemically indistinguishable by qualitative absorption tests. Qualitative antigenic differences were shown to exist between low density lipoproteins and high density lipoproteins. Quantitative precipitin reactions showed that low density lipoproteins Sf 6 and Sf 13 were immunochemically very similar. However, they differed with respect to the amount of antigen nitrogen required for maximum precipitation. Agar diffusion analyses were performed; the results suggest heterogeneity of lipoproteins by this criterion.

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