Immunological comparison of rat, rabbit, and human microsomal cytochromes P-450

Guengerich, F. Peter; Wang, P; Mason, P S; Mitchell, Mike

doi:10.1021/bi00512a002

Cited by 78 publications

(66 citation statements)

References 42 publications

(50 reference statements)

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“…Antibodies were raised in female New Zealand White rabbits immunized with the purified rat liver NADPH -P-450 reductase. Antisera from three rabbits were pooled and immunoglobulin G preparations were isolated as described previouly [21].…”

Section: Methodsmentioning

confidence: 99%

“…Anti-(NADPH -P-450 reductase) (0, 1.0, 2.5, 5.0, 7.5, 10.0, or 15.0 mg immunoglobulin G/mg microsomal protein) was preincubated with the variously induced microsomal preparations at 22°C for 30 min prior to performing warfarin metabolism [21]. The microsomes were then assayed for NADPH -cytochrome c reductase and warfarin hydroxylase activity.…”

Section: The Effect Of Anti-(nadph-p-450 Reductase) On Microsomal Warmentioning

confidence: 99%

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Cytochrome P‐450 isozyme/isozyme functional interactions and NADPH‐cytochrome P‐450 reductase concentrations as factors in microsomal metabolism of warfarin

Kaminsky

Guengerich

1985

European Journal of Biochemistry

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The basis for our previous observations [Kaminsky, L. S., Guengerich, F. P., Dannan, G. A. & Aust, S. D. (1983) Arch. Biochem. Biophys. 225, 398 -4041 that rates of microsomal metabolism of warfarin were markedly less than the sum of rates of the reconstituted constituent isozymes of cytochrome P-450 has been investigated. Metabolism of warfarin to 4'-, 6-, 7-, 8-, and 10-hydroxywarfarin and dehydrowarfarin by highly purified rat liver cytochrome P-450 (P-450) isozymes reconstituted with NADPH -cytochrome P-450 reductase and by hepatic microsomes from variously pretreated rats was used to probe functional consequences of P-450 isozyme/isozyme interactions and of the effect of microsomal reductase concentrations. Binary mixtures of P-450 isozymes were reconstituted and the regioselectivity and stereoselectivity were used to probe metabolism by each individual isozyme. The isozymes specifically inhibited each other to variable extents and the order of inhibitory potency 2 P-450BNF-B. The inhibition, possibly a consequence of aggregation, explains the low rate of microsomal metabolism relative to the metabolic potential of the component P-450 isozymes. When purified reductase was added to microsomes it appeared to bind to microsomes at different sites from endogenous reductase and it enhanced warfarin hydroxylase activity only to a minor extent, thus possibly precluding low reductase concentrations from being a major factor in the relatively low rates of microsomal metabolism. Antibody to the reductase differentially inhibited microsomal metabolism ofthat the reductase and P-450 isozymes may be microsomal preparations.warfarin by the various P-450 isozymes. The results suggest located differently relative to one another in the various The first resolution of the hepatic monooxygenase system into solubilized fractions comprising cytochrome P-450, NADPH -cytochrome P-450 reductase, and a heat-stable component was reported in 1968 [l]. Reconstitution of the solubilized and purified components of hepatic monooxygenases into systems which catalyse the metabolism of a wide variety of compounds was subsequently extensively investigated [2, 31. The interaction of highly purified P-450 [4 -61 and NADPH -P-450 reductase [7 -91 from PB-induced rats in a reconstituted system is reversible, governed by mass action, and leads to a 1 : 1 complex (dissociation constant approximately 0.05 pM) which is essential for catalysis [lo, 113. The association between the cytochrome and reductase is slow relative to the rate of electron transfer [12] although this conclusion may be an artifact of the methods used. Some studies with reconstituted systems have been interpreted to support the hypothesis of a fluid lipid matrix for the P-450 isozymes and reductase in the microsomal membrane, where the enzymes have rapid lateral mobility [13]. Other studies Correspondence to L. S . Kaminsky Abbreviutions. P-450, microsomal cytochrome P-450; PB, phenobarbital; BNF, 2-naphthoflavone; PCN, pregnenolone-16a-carbonitrile; 3-MC, 3-methylcholanthrene; H...

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Section: Methodsmentioning

confidence: 99%

Section: The Effect Of Anti-(nadph-p-450 Reductase) On Microsomal Warmentioning

confidence: 99%

Cytochrome P‐450 isozyme/isozyme functional interactions and NADPH‐cytochrome P‐450 reductase concentrations as factors in microsomal metabolism of warfarin

Kaminsky

Guengerich

1985

European Journal of Biochemistry

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“…6, 7). The regulation of CYP expression is in part tissue-specific (8). Marked enzymatic activities of CYPs 1A1, 2E1, and 3A4 have been demonstrated in the human head and neck squamous epithelium (9).…”

Section: Introductionmentioning

confidence: 99%

Cytochrome P450 and Glutathione Transferase Expression in Squamous Cell Cancer

Ali¹,

El-Rayes²,

Heilbrun³

et al. 2004

Clinical Cancer Research

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Purpose: The cytochrome P-450 (CYP) and glutathione S-transferase (GST) enzyme systems modulate the carcinogenic effects of tobacco. Therefore, the expression of these enzymes may be in part responsible for the observed interindividual and inter-racial differences in the risk of development of squamous cell carcinoma of the head and neck (SCCHN). The first aim of this study was to evaluate the feasibility of measuring the expression of the CYP and GST in target tissue from the head and neck. The second aim was to compare the expression of CYPs 1A1, 2E1, and 3A4 in squamous epithelium from African-American and Caucasian pediatric patients. The third aim was to compare the expression of CYPs 1A1, 2E1, 3A4, and GST-on the p16 expression in patients with SCCHN.Experimental Design: The expression of CYP 1A1, 2E1, 3A4, GST-, and p16 was quantified by immunoblotting. Expression of CYPs 1A1, 2E1, and 3A4 was quantified in tissue from 160 pediatric patients undergoing tonsillectomy. Expression of CYPs 1A1, 2E1, 3A4, GST-, and p16 was determined in 46 resected SCCHN patients.Results: Large interindividual variability in the expression of these enzymes was observed in the pediatric and adult populations. No significant difference was observed in CYP 1A1, 2E1, and 3A4 expression of Caucasian and African-American patients. There was no correlation between p16 and enzyme expression in patients with SCCHN.Conclusion: Evaluation of CYP expression in the target tissue of interest is feasible. The clinical significance of CYPs and GST-alterations in the risk of developing SCCHN will need to be investigated in larger trials.

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“…These two genes appear to code for two proteins that were named cytochrome P-450c and d (10). Early immunological data of Guengerich and Mason (4) showed that these proteins occur in the liver of untreated animals and are strongly induced by methylcholanthrene. In addition, these enzymes have been found in several extrahepatic tissues.…”

Section: Discussionmentioning

confidence: 99%

“…This approach has been chosen because the liver consists mainly of a single cell type, the hepatocyte, and because this organ contains a considerable amount of several cytochromes P450, some of which can be induced by xenobiotics. Only very few studies have been concerned with cytochromes P450 in extrahepatic tissues (4)(5)(6). In these studies antibodies against purified cytochrome P450 isozymes have been used.…”

Section: Introductionmentioning

confidence: 99%

Studies of the expression of the cytochrome P450IA, P450IIB, and P450IIC gene family in extrahepatic and hepatic tissues.

Friedberg

Siegert

Grassow

et al. 1990

Environ Health Perspect

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We have studied the expression of three P-450 gene subfamilies in hepatic and extrahepatic tissues using the sensitive RNAse A protection assay. Members of the P4501A subfamily, which encodes the major methylcholanthrene-inducible cytochromes P-450, were found to be not expressed in extrahepatic tissues of untreated animals, raising the question whether these P-450 play a role in the metabolism of carcinogens in unexposed individuals. In contrast, members of the P45011B family, some of which encode the major phenobarbital-inducible cytochromes P-450, were found to be expressed in some extrahepatic tissues of untreated rats and here most notably in the lung and in sebaceous glands. Members of the P450IIC family, which encode some constitutively expressed cytochromes P-450, were found to be expressed exclusively in the liver.

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Immunological comparison of rat, rabbit, and human microsomal cytochromes P-450

Cited by 78 publications

References 42 publications

Cytochrome P‐450 isozyme/isozyme functional interactions and NADPH‐cytochrome P‐450 reductase concentrations as factors in microsomal metabolism of warfarin

Cytochrome P‐450 isozyme/isozyme functional interactions and NADPH‐cytochrome P‐450 reductase concentrations as factors in microsomal metabolism of warfarin

Cytochrome P450 and Glutathione Transferase Expression in Squamous Cell Cancer

Studies of the expression of the cytochrome P450IA, P450IIB, and P450IIC gene family in extrahepatic and hepatic tissues.

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