Induction of monooxygenase system and incorporation of radioactive label from 2-14C-lysine into liver microsomal fraction of phenobarbital-treated rats fed a diet deficient in lysine, methionine, threonine, and vitamins A, C, and E

1991 ◽  
Vol 111 (3) ◽  
pp. 316-319
Author(s):  
T. Zh. Nurmagambetov ◽  
B. B. Amirov ◽  
T. K. Kuanysheva ◽  
T. Sh. Sharmanov
Keyword(s):  
Microsomal Fraction ◽  
Monooxygenase System ◽  
Radioactive Label ◽  
Liver Microsomal Fraction

Influence of 1,4-benzdiazepin-2-ones on rat liver microsomal fraction and hepatocytes

1987 ◽  
Vol 21 (1) ◽  
pp. 5-8
Author(s):  
T. I. Davidenko ◽  
O. V. Sevast'yanov ◽  
L. N. Yakubovskaya
Keyword(s):  
Rat Liver ◽  
Microsomal Fraction ◽  
Liver Microsomal Fraction

scholarly journals Loss of haem in rat liver caused by the porphyrogenic agent 2-allyl-2-isopropylacetamide

1971 ◽  
Vol 124 (4) ◽  
pp. 767-777 ◽  
Author(s):  
F. De Matteis
Keyword(s):  
Rat Liver ◽  
Microsomal Fraction ◽  
Direct Evidence ◽  
Gradual Increase ◽  
Rapid Loss ◽  
Metabolizing Enzymes ◽  
Liver Microsomal Fraction ◽  
Green Pigments ◽  
Cytochrome P 450 ◽  
Increased Activity

1. The effect of a single dose of 2-allyl-2-isopropylacetamide on the cytochrome P-450 concentration in rat liver microsomal fraction was studied. The drug caused a rapid loss of cytochrome P-450 followed by a gradual increase to above the normal concentration. 2. The loss of cytochrome P-450 was accompanied by a loss of microsomal haem and by a brown–green discoloration of the microsomal fraction suggesting that a change in the chemical constitution of the lost haem had taken place. Direct evidence for this was obtained by prelabelling the liver haems with radioactive 5-aminolaevulate: the drug caused a loss of radioactivity from the haem with an increase of radioactivity in a fraction containing certain un-identified green pigments. 3. Evidence was obtained by a dual-isotopic procedure that rapidly turning-over haem(s) may be preferentially affected. 4. The loss of cytochrome P-450 as well as the loss of microsomal haem and the discoloration of the microsomal fraction were more intense in animals pretreated with phenobarbitone and were much less evident when compound SKF 525-A (2-diethylaminoethyl 3,3-diphenylpropylacetate) was given before 2-allyl-2-isopropylacetamide, suggesting that the activity of the drug-metabolizing enzymes may be involved in these effects. 5. The relevance of the destruction of liver haem to the increased activity of 5-aminolaevulate synthetase caused by 2-allyl-2-isopropylacetamide is discussed.

scholarly journals The effect of magnesium ions on the diemthylaniline oxidation rate and electron transfer in liver microsomal fraction

1973 ◽  
Vol 136 (2) ◽  
pp. 371-379 ◽  
Author(s):  
A. I. Archakov ◽  
I. I. Karuzina ◽  
I. S. Kokareva ◽  
G. I. Bachmanova
Keyword(s):  
Electron Transfer ◽  
Fluorescence Quantum Yield ◽  
Sharp Increase ◽  
Microsomal Fraction ◽  
Magnesium Ions ◽  
Total Rate ◽  
Nadph Oxidation ◽  
Liver Microsomal Fraction ◽  
Rate Limiting ◽  
Cytochrome P 450

1. Reactions of N-demethylation, p-hydroxylation and N-oxidation of one substrate, i.e. dimethylaniline, have been used to show that the activating effect of Mg2+ takes place only in the first two reactions. 2. An increase in Vmax. of N-demethylation of dimethylaniline is accompanied by an increase in Km. In the p-hydroxylation of dimethylaniline Vmax. increases whereas Km does not change. A comparison of the changes in the Km values of these reactions with the change in Ks shows that in both cases Km does not characterize the affinity of cytochrome P-450 for dimethylaniline. 3. The rate-limiting site of N-demethylation and p-hydroxylation of dimethylaniline, as well as the total rate of NADPH oxidation in the presence of dimethylaniline, is between cytochromes b5 and P-450. Addition of Mg2+ to the incubation medium changes the hydrophobic environment of phosphatidylcholine in the membrane, the process being accompanied by a sharp increase in the fluorescence quantum yield of 8-anilinonaphthalene-1-sulphonate.

scholarly journals Fatty acid stimulation of membrane phosphatidylinositol hydrolysis by brain phosphatidylinositol phosphodiesterase

1979 ◽  
Vol 178 (2) ◽  
pp. 497-500 ◽  
Author(s):  
R F Irvine ◽  
A J Letcher ◽  
R M Dawson
Keyword(s):  
Arachidonic Acid ◽  
Oleic Acid ◽  
Fatty Acid ◽  
Acid Content ◽  
Microsomal Fraction ◽  
Fatty Acid Content ◽  
Membrane Bound ◽  
Liver Microsomal Fraction ◽  
Hydrolysis Of ◽  
Stimulation Of

The hydrolysis of membrane-bound phosphatidylinositol in rat liver microsomal fraction by the soluble phosphatidylinositol phosphodiesterase from rat brain was markedly stimulated by oleic acid or arachidonic acid. The stimulation did not require added calcium, although it was abolished by EDTA. Lysophosphatidylcholine also totally suppressed the stimulation. A possible role for the fatty acid content of a membrane in controlling phosphatidylinositol turnover is suggested.

scholarly journals Binding of radioiodinated propylthiouracil to rat liver microsomal fractions. Stimulation by substrates for iodothyronine 5′-deiodinase

1979 ◽  
Vol 183 (1) ◽  
pp. 167-169 ◽  
Author(s):  
T J Visser ◽  
E Van Overmeeren
Keyword(s):  
Rat Liver ◽  
Enzyme Preparation ◽  
Microsomal Fraction ◽  
Sodium Sulphite ◽  
Enzyme Complex ◽  
Deiodinase Activity ◽  
Liver Microsomal Fraction ◽  
Thiouracil Derivatives

Previous studies have shown that 2-thiouracil derivatives are uncompetitive inhibitors of iodothyronine 5′-deiodinase activity of rat liver microsomal fraction. Therefore the interaction of radioiodinated 6-propyl-2-thiouracil with rat liver microsomal fraction and the effect of substrate, cofactor and other inhibitors of 5′-deiodinase activity activity were investigated. It was found that micromolar concentrations of, in order of increasing potency, 3,5-diiodotyrosine, thyroxine, 3,3′,5′-tri-iodothyronine and 3′,5′-di-iodothyronine significantly enhanced binding of 5-[125I]iodo-6-propyl-2-thiouracil to the enzyme preparation. This stimulation was not seen in the presence of 1 mM dithiothreitol, 0.1 mM-6-propyl-2-thiouracil, 0.1 mM-6-propyl-2-thiouracil, 0.1 M-2-mercapto-1-methylimidazole or 1 mM-sodium sulphite. These results support the hypothesis that thiouracil derivatives inhibit 5′-deiodinase activity by forming a mixed disulphide with an intermediate enzyme complex, probably a sulphenyl iodide.

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