Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.99.3 (diaphorase)
 5,903 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have discovered cytochrome P450 and associated monooxygenase activities in microsomes prepared from spinal cord tissues from rats and a human. Cytochrome P450 levels and nicotinamide adenine dinucleotide phosphate cytochrome c reductase activities in microsomes from rat spinal cord were similar to those observed from the whole brain. However, certain monooxygenase activities were significantly lower in the rat spinal cord microsomes as compared to the corresponding activities observed in the whole brain. Cytochrome P450-mediated monooxygenase activities were also detectable in microsomes prepared from human spinal cord. Immunoblot analyses of rat and human spinal cord microsomes using antisera to various forms of hepatic cytochrome P450 namely (2B1 + 2B2), 1A1, 1A2 and 2E1 revealed the presence of immunologically similar forms. The spinal cord microsomes also cross-reacted with the antiserum to the phenobarbital-inducible form of rat brain cytochrome P450. Immunocytochemical stain was predominant in the gray horns of the rat spinal cord. At the cervical level, lamina 1 and 2 representing the substantia gelatinosa were intensely stained. In the ventral horns, lamina 7, 8 and 9 containing the large motor neurons were strongly labelled, while small neurons revealed variable staining. In the white matter, the glial cells were stained but the axons remained non-reactive.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cytochrome P450 and associated monooxygenase activities in the rat and human spinal cord: induction, immunological characterization and immunocytochemical localization. 747 69

We obtained information on the full length tobacco NADPH-cytochrome P450 oxidoreductase (P450 reductase) by a combination of the cDNA clone pCTR1 and the genomic DNA clone pGTR1. The deduced primary structure consisting of 713 amino acid residues contained sequences corresponding to FMN, FAD, and NADPH-binding regions. Based on this information, we prepared the full-length cDNA pFTR of tobacco P450 reductase by RT-PCR and expressed it in the yeast Saccharomyces cerevisiae. The transformed yeast cells carrying pFTR produced the corresponding mRNA and protein, and had increased cytochrome c reductase activity in the microsomes. An in vitro reconstitution system of the yeast microsomal fractions expressed tobacco P450 reductase and rat P450 1A1 showed an increased 7-ethoxycoumarin O-deethylase activity. These results indicated that tobacco P450 reductase expressed in the yeast microsomes coupled with rat P450 1A1 resulting in an increased monooxygenase activity.
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PMID:Molecular cloning and expression in Saccharomyces cerevisiae of tobacco NADPH-cytochrome P450 oxidoreductase cDNA. 972 Feb 24

Roquefortine, a cyclopeptide derived from the diketopiperazine cyclo(Trp-dehydroHis), is a secondary metabolite produced by several Penicillium species. It has been reported to cause neurotoxic effect and to inhibit Gram-positive bacteria growth. The mechanisms responsible for its toxicity and metabolism are still unknown. In this study, we investigated the interaction of roquefortine with mammalian cytochromes P450. Roquefortine interaction with rat and human liver cytochromes P450 was monitored by difference UV-vis spectroscopy. It was found to interact with different forms of the cytochromes, giving rise to a type II difference spectrum, characteristic of the binding of an amino function to the heme iron. Roquefortine exhibited high affinity for microsomes from rats treated with various inducers, the K(s) values being in the range 0.2-8 microM. Similar results were observed with human P450 enzymes 1A1, 1A2, 2D6, and 3A4. Roquefortine had no effect on NAPDH cytochrome c reductase. Therefore, inhibition of NADPH consumption was observed using various rat liver microsomes alone or in the presence of 100 microM testosterone in the case of dexamethasone (DEX)-rat microsomes. Enzymatic inhibition was studied in terms of P450 3A activities, i.e., testosterone 6beta-hydroxylase (IC(50) around 10 microM) or bromocriptine metabolism (IC(50) > 50 microM) using DEX-rat liver microsomes or P450 3A4, benzphetamine N-demethylase using phenobarbital-rat liver microsomes (IC(50) > 30 microM), and ethoxyresorufin metabolism using 3-methylcholanthrene-rat liver microsomes (IC(50) 0.1 microM), P450 1A1, and 1A2. Roquefortine was compared with compounds of similar structure: cyclo(Phe-His), cyclo(Phe-dehydroHis), cyclo(Trp-His), phenylahistin. These studies indicate that the =N- imidazole moiety coordinates with the heme iron, and suggest that the dehydroHis moiety and the presence of a fused tetracycle play an important part in roquefortine inhibitory power.
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PMID:Molecular requirements for inhibition of cytochrome p450 activities by roquefortine. 1155 41

Diaphorase was studied as a possible oxidoreductase participating in NO production from some vasorelaxants. In the presence of NADH or NADPH, diaphorase can convert selected NO donors, glycerol trinitrate (GTN) and formaldoxime (FAL) to nitrites and nitrates with NO as an intermediate. This activity of diaphorase was inhibited by diphenyleneiodonium (DPI) (inhibitor of some NADPH-dependent flavoprotein oxidoreductases), while it remained uninhibited by NG-nitro-L-arginine methyl ester (inhibitor of NO synthase) 7-Ethoxyresorufin (inhibitor of cytochrome P-450 1A1 and cytochrome P-450 NADPH-dependent reductase) inhibited the conversion of GTN only. Existence of NO as an intermediate of the reaction was supported by results of electron paramagnetic resonance spectroscopy. In addition to its ability to affect the above mentioned NO donors, diaphorase was able to reduce 2-phenyl-4,4,5,5,-tetramethylimidazoline-1-oxyl-3-oxide (PTIO) and thus to eliminate its NO scavenging effect. This activity of diaphorase could also be inhibited by DPI. The reaction of diaphorase with GTN and PTIO was not affected by superoxide dismutase (SOD) or catalase. Reaction of FAL with diaphorase was lowered with SOD by 38 % indicating the partial participation of superoxide anion probably generated by the reaction of diaphorase with NADH or NADPH. Catalase had no effect. Diaphorase could apparently be one of the enzymes participating in the metabolism of studied NO donors to NO. The easy reduction and consequent elimination of PTIO by diaphorase could affect its use as an NO scavenger in biological tissues.
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PMID:Diaphorase can metabolize some vasorelaxants to NO and eliminate NO scavenging effect of 2-phenyl-4,4,5,5,-tetramethylimidazoline-1-oxyl-3-oxide (PTIO). 1558 29