scholarly journals A novel olefinic rearrangement. The enzymic conversion of cholesta-7,9-dien-3β-ol into cholesta-8,14-dien-3β-ol

1972 ◽  
Vol 129 (2) ◽  
pp. 225-229 ◽  
Author(s):  
M. Akhtar ◽  
C. W. Freeman ◽  
A. D. Rahimtula ◽  
D. C. Wilton
Keyword(s):  
Rat Liver ◽  
Liver Homogenate ◽  
High Yield ◽  
Supernatant Fraction ◽  
Anaerobic Conditions

1. [3α-3H]Cholesta-7,9-dien-3β-ol is converted in high yield into cholesterol by a 10000gav. supernatant fraction of rat liver homogenate. 2. Incubation of cholesta-7,9-dien-3β-ol with [4-3H]NADPH and rat liver microsomal fractions under anaerobic conditions resulted in3H being incorporated into the 14α-position of cholest-7-en-3β-ol. 3. Under anaerobic conditions in the absence of NADPH cholesta-7,9-dien-3β-ol was isomerized into cholesta-8,14-dien-3β-ol by rat liver microsomal fractions.

Biosynthesis of 1,2-3H and 4-14C steroid sulfates of high specific activity

1970 ◽  
Vol 48 (1) ◽  
pp. 148-150 ◽  
Author(s):  
J. Torday ◽  
G. Hall ◽  
M. Schweitzer ◽  
C. J. P. Giroud
Keyword(s):  
Rat Liver ◽  
Specific Activity ◽  
Liver Homogenate ◽  
High Specific Activity ◽  
Supernatant Fraction ◽  
Metabolic Studies

A supernatant fraction of rat liver homogenate enriched with ATP was used for the biosynthesis of the ester sulfates of several 3H and 14C steroids of the pregn-4-ene series. The method provides a simple means to prepare steroid sulfates of high specific activity for use in either metabolic studies or as reference compounds in the quantification of such conjugates by isotope assays.

METHYLATION OF THE 3-OH POSITION OF CATECHOL ACIDS BY RAT LIVER AND KIDNEY PREPARATIONS

1958 ◽  
Vol 36 (5) ◽  
pp. 491-497 ◽  
Author(s):  
J. Pellerin ◽  
A. D'Iorio
Keyword(s):  
Enzymatic Activity ◽  
Rat Liver ◽  
Paper Chromatography ◽  
Reduced Glutathione ◽  
Liver Homogenate ◽  
Supernatant Fraction ◽  
Hydroxybenzoic Acid ◽  
Dihydroxybenzoic Acid ◽  
Kidney Homogenate ◽  
Liver And Kidney

3,4-Dihydroxybenzoic acid, 3,4-dihydroxyphenylacetic acid, 3,4-dihydroxymandelic acid, and 3,4-dihydroxycinnamic acid were separately incubated with L-methionine-methyl-C14 in the presence of rat liver or kidney homogenate. In each case, the radioactive metabolite separated by paper chromatography was found to have migrating properties similar to those of the 3-methoxy-4-hydroxyphenolic acid. This reaction was enhanced by the addition of ATP, Mg++, and reduced glutathione. When 3-hydroxybenzoic acid was incubated in this medium no methylated derivative was obtained. Preliminary experiments indicated that the enzymatic activity was contained mostly in the supernatant fraction. It was also noted that liver homogenate was much more active than kidney homogenate in methylating catechol acids.

scholarly journals The function of subcellular fractions in the oxidation of glutathione in rat liver homogenate

1970 ◽  
Vol 117 (5) ◽  
pp. 951-956 ◽  
Author(s):  
P. C. Jocelyn
Keyword(s):  
Uric Acid ◽  
Xanthine Oxidase ◽  
Rat Liver ◽  
Liver Homogenate ◽  
No Oxidation ◽  
Urate Oxidase ◽  
Supernatant Fraction ◽  
Endogenous Substrate ◽  
Additional Protein ◽  
Microsome Fraction

1. The aerobic loss of GSH added to the supernatant fraction from rat liver is much increased by including the microsome fraction, which both inhibits the concurrent reduction of the GSSG formed and also augments the net oxidation rate. 2. Oxidation occurs with a mixture of dialysed supernatant and a protein-free filtrate; the latter is replaceable by hypoxanthine and the former by xanthine oxidase, whereas fractions lacking this enzyme give no oxidation. 3. In all these instances augmentation occurs with microsomes, with fractions having urate oxidase activity and with the purified enzyme; uric acid and microsomes alone also support the oxidation. 4. Evidence implicating additional protein factors is discussed. 5. It is suggested that GSH oxidation by homogenate is linked through glutathione peroxidase to the reaction of endogenous substrate with supernatant xanthine oxidase and of the uric acid formed with peroxisomal urate oxidase.

METHYLATION OF THE 3-OH POSITION OF CATECHOL ACIDS BY RAT LIVER AND KIDNEY PREPARATIONS

1958 ◽  
Vol 36 (1) ◽  
pp. 491-497 ◽  
Author(s):  
J. Pellerin ◽  
A. D'Iorio
Keyword(s):  
Enzymatic Activity ◽  
Rat Liver ◽  
Paper Chromatography ◽  
Reduced Glutathione ◽  
Liver Homogenate ◽  
Supernatant Fraction ◽  
Hydroxybenzoic Acid ◽  
Dihydroxybenzoic Acid ◽  
Kidney Homogenate ◽  
Liver And Kidney

3,4-Dihydroxybenzoic acid, 3,4-dihydroxyphenylacetic acid, 3,4-dihydroxymandelic acid, and 3,4-dihydroxycinnamic acid were separately incubated with L-methionine-methyl-C14 in the presence of rat liver or kidney homogenate. In each case, the radioactive metabolite separated by paper chromatography was found to have migrating properties similar to those of the 3-methoxy-4-hydroxyphenolic acid. This reaction was enhanced by the addition of ATP, Mg++, and reduced glutathione. When 3-hydroxybenzoic acid was incubated in this medium no methylated derivative was obtained. Preliminary experiments indicated that the enzymatic activity was contained mostly in the supernatant fraction. It was also noted that liver homogenate was much more active than kidney homogenate in methylating catechol acids.

scholarly journals 4,4′-dimethylcholesta-7,9,14-trienol is an intermediate in the demethylation of dihydroagnosterol

1977 ◽  
Vol 166 (1) ◽  
pp. 17-20 ◽  
Author(s):  
I A F Tavares ◽  
K A Munday ◽  
D C Wilton
Keyword(s):  
Rat Liver ◽  
Liver Homogenate ◽  
Anaerobic Conditions ◽  
Microsomal Preparation ◽  
Aerobic Conditions ◽  
Liver Microsomal Preparation

1. 4,4′-Dimethylcholesta-7,9,14-trienol is an intermediate in the metabolism of dihydroagnosterol to cholesterol by rat liver homogenate. 2. This triene is reduced by a rat liver microsomal preparation in the presence of NADPH to give 4,4′-dimethylcholesta-7,9-dienol under anaerobic conditions. 3. Reduction of the triene in the presence of [4-3H2]NADPH resulted in the incorporation of 3H into the product. 4. Under aerobic conditions the triene is converted into cholesterol by a rat liver homogenate.

scholarly journals Biosynthesis of cyclopropyl long-chain fatty acids from cyclopropanecarboxylic acid by mammalian tissues in vitro

1968 ◽  
Vol 109 (3) ◽  
pp. 449-455 ◽  
Author(s):  
W. G. Duncombe ◽  
T. J. Rising
Keyword(s):  
Fatty Acids ◽  
Rat Liver ◽  
Liver Homogenate ◽  
Supernatant Fraction ◽  
Long Chain Fatty Acids ◽  
Straight Chain ◽  
Cyclopropanecarboxylic Acid ◽  
Mammalian Tissues ◽  
Chain Fatty Acids

1. Radioactivity from cyclopropane[14C]carboxylic acid is incorporated into fatty acids in vitro by rat and guinea-pig adipose tissue, by rat liver slices and by the supernatant fraction of rat liver homogenate. 2. The labelled acids are different from endogenous straight-chain fatty acids, and evidence is produced that they consist of a cyclopropyl ring in the ω-position, the remainder of the chain being built up from C2 units (not derived from cyclopropanecarboxylic acid) in the normal way via the malonate pathway. 3. It is suggested that these unnatural acids have some metabolic effect related to the hypoglycaemic action of cyclopropanecarboxylic acid.

Cholesterol metabolism and vitamin B6. I. Hepatic cholesterogenesis and pyridoxine deficiency

1969 ◽  
Vol 47 (6) ◽  
pp. 631-635 ◽  
Author(s):  
P. J. Lupien ◽  
C. M. Hinse ◽  
M. Avery
Keyword(s):  
Rat Liver ◽  
High Speed ◽  
Cholesterol Metabolism ◽  
Reductase Activity ◽  
Liver Microsomes ◽  
Liver Homogenate ◽  
Supernatant Fraction ◽  
Liver Cholesterol ◽  
Pyridoxine Deficiency ◽  
Hepatic Cholesterogenesis

Hepatic cholesterogenesis was studied in pair-fed and pyridoxine-deficient rats as well as in rat liver homogenate systems. Crossover of various subcellular components from pair-fed homogenates into pyridoxine-deficient homogenate systems and vice versa was also done.On 8 weeks of pyridoxine deficiency, acetate-14C incorporation rates into liver cholesterol increased by a factor of approximately 10. The same phenomenon was observed with the total liver homogenate systems.Pyridoxine deficiency does not appear to affect HMG-CoA reductase activity of pyridoxine-deficient liver microsomes sufficiently to explain the rapid acetate-1-14C incorporation rates in this same tissue. The activating system(s) responsible for the 10-fold increase in acetate-14C incorporation rates into pyridoxine-deficient rat liver cholesterol appears to be located in the high-speed supernatant fraction. Other subcellular components such as lysosomes and mitochondria are probably implicated to some extent in this phenomenon. The results indicate that vitamin B6 is necessary for normal hepatic cholesterogenesis in the rat.The significance of these findings and the possible relationship between these factors are discussed.

scholarly journals The nature of the acid-volatile selenium in the liver of the male rat

1973 ◽  
Vol 134 (1) ◽  
pp. 283-293 ◽  
Author(s):  
A. T. Diplock ◽  
Christine P. J. Caygill ◽  
Elizabeth H. Jeffery ◽  
C. Thomas
Keyword(s):  
Vitamin E ◽  
Rat Liver ◽  
Microsomal Fraction ◽  
Current Knowledge ◽  
Liver Homogenate ◽  
Selenium Deficiency ◽  
Male Rat ◽  
Anaerobic Conditions ◽  
Volatile Material ◽  
Acid Labile

1. The properties of rat liver acid-volatile selenium have been compared with those of H2Se and (CH3)2Se. 2. In model experiments oxidation-sensitive H275Se was trapped quantitatively under anaerobic conditions in 0.1m-AgNO3, and (CH3)275Se was trapped quantitatively in 8m-HNO3. The acid-labile selenium of a liver homogenate, and of a microsomal fraction, was found to behave quite unlike (CH3)275Se and in a manner indistinguishable from H275Se. 3. It was concluded that the acid-volatile material is certainly not (CH3)2Se and that it is probably H2Se. 4. The significance of these findings is discussed in relation to current knowledge about the metabolism and detoxication of selenium, and a scheme is proposed which incorporates this knowledge with recent observations on the interactions between trace amounts of selenium and tocopherol, and the production of acute selenium deficiency by Ag+ in vitamin E-deficient rats.

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