Studies on the purification of glucose 6-phosphatase from rabbit liver microsomal fraction

1980 ◽  
Vol 8 (3) ◽  
pp. 389-390 ◽  
Author(s):  
GORDON F. BICKERSTAFF ◽  
BRIAN BURCHELL
Keyword(s):  
Microsomal Fraction ◽  
Rabbit Liver ◽  
Liver Microsomal Fraction

scholarly journals Studies on the mechanism of hepatic microsomal N-oxide formation. The role of cytochrome P-450 and mixed-function amine oxidase in the N-oxidation of NN-dimethylaniline

1977 ◽  
Vol 164 (3) ◽  
pp. 487-496 ◽  
Author(s):  
P Hlavica ◽  
M Kehl
Keyword(s):  
Microsomal Fraction ◽  
Amine Oxidase ◽  
The Other ◽  
Rabbit Liver ◽  
Oxide Formation ◽  
Intact Rabbit ◽  
Liver Microsomal Fraction ◽  
Nadph Dehydrogenase ◽  
Cytochrome P 450

Evidence is established for the existence of alternative metabolic routes of N-oxidation of NN-dimethylaniline in rabbit liver microsomal fraction. One pathway involves the participation of two types of cytochrome P-450 with different sensitivities towards heat. Both types may represent distinct haemoprotein species or two physical forms of a single pigment. The other pathway is represented by the mixed-function amine oxidase. The enzyme lacks NADPH dehydrogenase activity and is insensitive to treatment with 2-bromo-4'-nitroacetophenone and steapsin: it catalyses N-oxidation of imipramine, trimethylamine and NN-dimethylaniline in molar proportions considerably different from those of the cytochrome P-450-supported reactions. Cytochrome P-450 is estimated to account for the formation of at least 50-60% of the total NN-dimethylaniline N-oxide formed in the intact rabbit liver microsomal fraction, the remainder arising from the action of the mixed-function amine oxidase.

scholarly journals Oxidation of arylcyclopropanes by rabbit liver cytochrome P-450. Mechanistic implications of a multiple oxidation

1985 ◽  
Vol 232 (1) ◽  
pp. 199-203 ◽  
Author(s):  
C J Suckling ◽  
D C Nonhebel ◽  
L Brown ◽  
K E Suckling ◽  
S Seilman ◽  
...  
Keyword(s):  
Active Site ◽  
Microsomal Fraction ◽  
Cumene Hydroperoxide ◽  
Rabbit Liver ◽  
Microsomal Cytochrome ◽  
Liver Cytochrome ◽  
Liver Microsomal Fraction ◽  
Reconstituted System ◽  
Mechanism Of Oxidation ◽  
Cytochrome P 450

The arylcyclopropanes (cyclopropylarenes) cyclopropylbenzene and diphenylcyclopropane are oxidized by rabbit liver microsomal cytochrome P-450, both by the microsomal fraction and by the purified cytochrome in a reconstituted system. The products formed, principally benzoic acid, are due to an unusual triple oxidation of the substrate, which probably remains attached to the active site during the several steps of the oxidation. Both substrates were found to be inhibitors of the cytochrome P-450-dependent O-de-ethylation of 7-ethoxycoumarin. Model oxidation studies with cumene hydroperoxide as oxidizing agent and rabbit liver microsomal fraction as source of enzyme gave similar products to the microsomal and reconstituted systems. The significance of these results in the mechanism of oxidation catalysed by cytochrome P-450 is discussed.

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.

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