Cytochrome P-450 production and benzo[a]pyrene hydroxylase activity and inducibility in Saccharomyces cerevisiae N.C.Y.C. 240 and its morphological variants N.C.Y.C. 753 and 754

1983 ◽  
Vol 11 (6) ◽  
pp. 710-710 ◽  
Author(s):  
DAVID J. KING ◽  
ANDREW BLATIAK ◽  
ALAN WISEMAN
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Hydroxylase Activity ◽  
Morphological Variants ◽  
Pyrene Hydroxylase ◽  
Cytochrome P 450

Expression of a human liver cytochrome P-450 protein with tolbutamide hydroxylase activity in Saccharomyces cerevisiae

Biochemistry ◽  
1989 ◽  
Vol 28 (12) ◽  
pp. 4993-4999 ◽  
Author(s):  
William R. Brian ◽  
Pramod K. Srivastava ◽  
Diane R. Umbenhauer ◽  
R. Stephen Lloyd ◽  
F. Peter Guengerich
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Human Liver ◽  
Hydroxylase Activity ◽  
Liver Cytochrome ◽  
Cytochrome P 450

1-Ethynylpyrene, a suicide inhibitor of cytochrome P-450 dependent benzo[a]pyrene hydroxylase activity in liver microsomes

Biochemistry ◽  
1984 ◽  
Vol 23 (17) ◽  
pp. 3827-3836 ◽  
Author(s):  
Liang Shang L. Gan ◽  
Abelardo L. Acebo ◽  
William L. Alworth
Keyword(s):  
Liver Microsomes ◽  
Hydroxylase Activity ◽  
Pyrene Hydroxylase ◽  
Cytochrome P 450

Enzymatic Synthesis of 4′-and 3′, 4′ -Hydroxylated Flavanones and Flavones with Flower Extracts of Sinningia cardinalis

1987 ◽  
Vol 42 (11-12) ◽  
pp. 1193-1199 ◽  
Author(s):  
K. Stich ◽  
G. Forkmann
Keyword(s):  
Enzymatic Synthesis ◽  
Microsomal Fraction ◽  
Chalcone Synthase ◽  
Condensation Reaction ◽  
Flavonoid Biosynthesis ◽  
Hydroxylase Activity ◽  
Key Enzyme ◽  
Flavone Synthase ◽  
Flavone Synthase Ii ◽  
Cytochrome P 450

Flowers of Sinningia (syn. Rechsteineria) cardinalis contain glycosides of the flavones apigenin (4′-OH) and luteolin (3′,4′-OH) respectively, and of the related 3-deoxyanthocyanidins apigeninidin and luteolinidin. Studies on substrate specificity of the key enzyme of flavonoid biosynthesis, chalcone synthase, revealed that the 3′,4′-hydroxylated flavonoids are formed by hydroxylation of flavonoid compounds rather than by incorporation of caffeoyl-CoA into the flavonoid skeleton during the condensation reaction. In fact, flavonoid 3′-hydroxylase activity could be demonstrat­ed in the microsomal fraction of the flower extracts. The enzyme catalyses hydroxylation of naringenin and apigenin in the 3′-position to eriodictyol and luteolin, respectively, with NADPH as cofactor. Besides flavanone 3′-hydroxylase a further NADPH-dependent enzyme activity (flavone synthase II) was observed in the microsomal fraction catalysing the oxidation of naringenin to apigenin and of eriodictyol to luteolin. The Cytochrome P-450 inhibitor ancymidol was found to abolish completely flavone synthase II activity, whereas flavonoid 3′-hydroxylase activity was not impaired.

Temperature Influence on Basal Activity and Induction of Mixed Function Oxygenase Activity in Fundulus heteroclitus

1979 ◽  
Vol 36 (11) ◽  
pp. 1400-1405 ◽  
Author(s):  
John J. Stegeman
Keyword(s):  
Cytochrome C ◽  
Fundulus Heteroclitus ◽  
Reductase Activity ◽  
Control Fish ◽  
Cytochrome C Reductase ◽  
Nadph Cytochrome ◽  
Pyrene Hydroxylase ◽  
Mixed Function Oxygenase ◽  
Cytochrome P 450 ◽  
Nadph Cytochrome C Reductase

Treatment of Fundulus heteroclitus acclimated to 6.5 °C with benzo(a)pyrene did not elicit any change in the levels of hepatic microsomal NADH- or NADPH-cytochrome c reductase activity, nor in the levels of cytochrome P-450 or its catalytic activities. However, the same treatment offish at 16 5 °C resulted in a marked induction of benzo(a)pyrene hydroxylase and NADPH-cytochrome c reductase. Cytochrome P-450 content was also higher in the warm, treated fish and the Soret maximum of reduced, CO-treated microsomes was shifted to the violet. Levels of aminopyrine demethylase and NADH-cytochrome c reductase activities did not show a significant treatment effect. At neither temperature could treated and control fish be distinguished on the basis of in vitro inhibition of benzo(a)pyrene hydroxylase activity by 7,8-benzoflavone. Levels of NADPH-cytochrome c reductase and benzo(a)pyrene hydroxylase activities were greater in control Fundulus acclimated to 6.5 °C than to 16.5 °C, when normalized to microsomal protein, but not when based on body weight. The results indicate that habitat temperature alone may not affect the capacity for initial hydrocarbon metabolism in fish, but that it can strongly influence the induction of cytochrome P-450. Key words: temperature, cytochrome P-450, hydrocarbon metabolism, mixed-function oxygenase, Fundulus heteroclitus

A second enzyme protecting mineralocorticoid receptors from glucocorticoid occupancy

1998 ◽  
Vol 274 (5) ◽  
pp. C1245-C1252 ◽  
Author(s):  
David J. Morris ◽  
Syed A. Latif ◽  
Michael D. Rokaw ◽  
Charles O. Watlington ◽  
John P. Johnson
Keyword(s):  
Glucocorticoid Receptors ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Mineralocorticoid Receptors ◽  
Hydroxylase Activity ◽  
A6 Cells ◽  
Ru 28318 ◽  
The One ◽  
Cytochrome P 450 ◽  
Significant Increment

We have confirmed that A6 cells (derived from kidney of Xenopus laevis), which contain both mineralocorticoid and glucocorticoid receptors, do not normally possess 11β-hydroxysteroid dehydroxgenase (11β-HSD1 or 11β-HSD2) enzymatic activity and so are without apparent “protective” enzymes. A6 cells do not convert the glucocorticoid corticosterone to 11-dehydrocorticosterone but do, however, possess steroid 6β-hydroxylase that transforms corticosterone to 6β-hydroxycorticosterone. This hydroxylase is cytochrome P-450 3A (CYP3A). We have now determined the effects of 3α,5β-tetrahydroprogesterone and chenodeoxycholic acid (both inhibitors of 11β-HSD1) and 11-dehydrocorticosterone and 11β-hydroxy-3α,5β-tetrahydroprogesterone (inhibitors of 11β-HSD2) and carbenoxalone, which inhibits both 11β-HSD1 and 11β-HSD2, on the actions and metabolism of corticosterone and active Na+ transport [short-circuit current ( I sc)] in A6 cells. All of these 11β-HSD inhibitory substances induced a significant increment in corticosterone-induced I sc, which was detectable within 2 h. However, none of these agents caused an increase in I sc when incubated by themselves with A6 cells. In all cases, the additional I sc was inhibited by the mineralocorticoid receptor (MR) antagonist, RU-28318, whereas the original I scelicited by corticosterone alone was inhibited by the glucocorticoid receptor antagonist, RU-38486. In separate experiments, each agent was shown to significantly inhibit metabolism of corticosterone to 6β-hydroxycorticosterone in A6 cells, and a linear relationship existed between 6β-hydroxylase inhibition and the MR-mediated increase in I scin the one inhibitor tested. Troleandomycin, a selective inhibitor of CYP3A, inhibited 6β-hydroxylase and also significantly enhanced corticosterone-induced I sc at 2 h. These experiments indicate that the enhanced MR-mediated I sc in A6 cells may be related to inhibition of 6β-hydroxylase activity in these cells and that this 6β-hydroxylase (CYP3A) may be protecting the expression of corticosterone-induced active Na+ transport in A6 cells by MR-mediated mechanism(s).

Sign in / Sign up

Export Citation Format

Share Document