8 results on '"CYTOCHROMES"'
Search Results
2. Mechanisms of Enzyme-Catalyzed Reduction of Two Carcinogenic Nitro-Aromatics, 3-Nitrobenzanthrone and Aristolochic Acid I: Experimental and Theoretical Approaches.
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Stiborová, Marie, Frei, Eva, Schmeiser, Heinz H., Arlt, Volker M., and Martínek, Václav
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CHEMICAL reduction , *ARISTOLOCHIC acid , *AROMATIC compounds , *CYTOCHROMES , *ACETYLTRANSFERASES , *SULFOTRANSFERASES , *CARCINOGENS - Abstract
This review summarizes the results found in studies investigating the enzymatic activation of two genotoxic nitro-aromatics, an environmental pollutant and carcinogen 3-nitrobenzanthrone (3-NBA) and a natural plant nephrotoxin and carcinogen aristolochic acid I (AAI), to reactive species forming covalent DNA adducts. Experimental and theoretical approaches determined the reasons why human NAD(P)H:quinone oxidoreductase (NQO1) and cytochromes P450 (CYP) 1A1 and 1A2 have the potential to reductively activate both nitro-aromatics. The results also contributed to the elucidation of the molecular mechanisms of these reactions. The contribution of conjugation enzymes such as N,O-acetyltransferases (NATs) and sulfotransferases (SULTs) to the activation of 3-NBA and AAI was also examined. The results indicated differences in the abilities of 3-NBA and AAI metabolites to be further activated by these conjugation enzymes. The formation of DNA adducts generated by both carcinogens during their reductive activation by the NOQ1 and CYP1A1/2 enzymes was investigated with pure enzymes, enzymes present in subcellular cytosolic and microsomal fractions, selective inhibitors, and animal models (including knock-out and humanized animals). For the theoretical approaches, flexible in silico docking methods as well as ab initio calculations were employed. The results summarized in this review demonstrate that a combination of experimental and theoretical approaches is a useful tool to study the enzyme-mediated reaction mechanisms of 3-NBA and AAI reduction. [ABSTRACT FROM AUTHOR]
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- 2014
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3. Phylogenomic reconstruction of archaeal fatty acid metabolism.
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Dibrova, Daria V., Galperin, Michael Y., and Mulkidjanian, Armen Y.
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FATTY acids , *ACETYLTRANSFERASES , *CYTOCHROMES , *MEVALONATE kinase , *RHODOPSIN , *GENETIC transformation , *BIOMASS energy - Abstract
While certain archaea appear to synthesize and/or metabolize fatty acids, the respective pathways still remain obscure. By analysing the genomic distribution of the key lipid-related enzymes, we were able to identify the likely components of the archaeal pathway of fatty acid metabolism, namely, a combination of the enzymes of bacterial-type β-oxidation of fatty acids [acyl-coenzyme A ( CoA) dehydrogenase, enoyl- CoA hydratase and 3-hydroxyacyl- CoA dehydrogenase] with paralogs of the archaeal acetyl- CoA C-acetyltransferase, an enzyme of the mevalonate biosynthesis pathway. These three β-oxidation enzymes working in the reverse direction could potentially catalyse biosynthesis of fatty acids, with paralogs of acetyl- CoA C-acetyltransferase performing addition of C 2 fragments. The presence in archaea of the genes for energy-transducing membrane enzyme complexes, such as cytochrome bc complex, cytochrome c oxidase and diverse rhodopsins, was found to correlate with the presence of the proposed system of fatty acid biosynthesis. We speculate that because these membrane complexes functionally depend on fatty acid chains, their genes could have been acquired via lateral gene transfer from bacteria only by those archaea that already possessed a system of fatty acid biosynthesis. The proposed pathway of archaeal fatty acid metabolism operates in extreme conditions and therefore might be of interest in the context of biofuel production and other industrial applications. [ABSTRACT FROM AUTHOR]
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- 2014
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4. Role of polymorphic N-acetyl transferase2 and cytochrome P4502E1 gene in antituberculosis treatment-induced hepatitis.
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Bose, Purabi Deka, Sarma, Manash Pratim, Medhi, Subhash, Das, Bhudev Chandra, Husain, Syed Akhtar, and Kar, Premashis
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HEPATOTOXICOLOGY , *TUBERCULOSIS treatment , *HEPATITIS , *ACETYLTRANSFERASES , *CYTOCHROMES , *ACETYLATOR status (Pharmacology) , *GENETIC polymorphisms , *PATIENTS - Abstract
Antituberculosis drugs, isoniazid and rifampicin, in combination, are known to develop drug-induced hepatotoxicity (DIH). A higher risk of DIH during antituberculosis treatment (ATT) has been reported in the Indian subcontinent compared to its Western counterparts. The role of genetic factors in a higher incidence of ATT hepatotoxicity in the Indian population is still unclear. The present study was aimed at investigating the role of the N-acetyltransferase2 (NAT2) and cytochrome P4502E1 (CYP2E1) gene polymorphisms in ATT hepatotoxicity. The study population included 218 pulmonary tuberculosis patients who were started on ATT and followed up for the occurrence of ATT-induced hepatitis. The genetic polymorphisms of the NAT2 and CYP2E1 genes were studied by polymerase chain reaction-restriction fragment length polymorphism. The occurrence of DIH was 18.8% (41/218). There was a higher prevalence of NAT2 slow-acetylator genotypes in DIH (70.73%) compared to non-DIH (44.63%; P < 0.05). The frequency of the NAT2*5/*7 and NAT2*6/*7 genotypes was significantly higher in DIH than non-DIH (19.51% vs 6.78%, and 19.51% vs 5.08%). No association of the CYP2E1 RsaI polymorphism could be demonstrated with DIH. However, the DraI C/D genotype of the CYP2E1 gene was mostly prevalent in DIH (85.37%), compared to non-DIH (64.41%) ( P < 0.05). Slow-acetylator status and the CYP2E1 C/D or C/C genotype together showed a higher frequency in DIH (65.85%) compared to non-DIH (28.81%) ( P < 0.0001). The study demonstrates for the first time a possible association between the DraI polymorphism of the CYP2E1 gene and the risk of ATT hepatotoxicity. The genotyping of the NAT2 and CYP2E1 genes could possibly identify the groups at highest risk of developing ATT-induced hepatitis prior to medication. [ABSTRACT FROM AUTHOR]
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- 2011
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5. Strategies to prevent N-acetyltransferase-mediated metabolism in a series of piperazine-containing pyrazalopyrimidine compounds.
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Rawal, J., Jones, R., Payne, A., and Gardner, I.
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ACETYLTRANSFERASES , *METABOLISM , *PIPERAZINE , *CYTOCHROME P-450 , *PYRIMIDINES , *CYTOCHROMES - Abstract
1. (1-Methyl-5-piperazin-1-yl-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-7-yl)-(5-methyl-pyridin-2-yl)-amine (UK-469,413) was identified as a lead compound in a new medicinal chemistry programme. UK-469,413 had good physicochemical properties and was slowly metabolized by cytochromes P450 in rat and human liver microsomes. 2. In the rat in vivo the compound was rapidly cleared. Subsequent studies showed that UK-469,413 was rapidly acetylated in rat liver cytosol to an N-acetylpiperazine metabolite that was the major circulating metabolite in rat plasma in vivo. 3. Analogues of UK-469,413 containing the unsubstituted piperazine moiety were rapidly acetylated in rat liver cytosol and had high plasma clearance in the rat in vivo. These compounds were also acetylated in human liver cytosol and the N-acetyl metabolite was a major metabolite formed in incubations with cryopreserved human hepatocytes. 4. Using specific inhibitors, correlation analysis and expressed human N-acetyltransferase (NAT) enzymes the compounds were shown to be substrates of the polymorphically expressed NAT-2 isozyme. 5. Further experiments showed that it was possible to make small structural changes to the piperazine group that retained potency but prevented metabolism by NAT. [ABSTRACT FROM AUTHOR]
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- 2008
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6. CYP1A2 and NAT2 genotype/phenotype relations and urinary excretion of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) in a human dietary intervention study
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Moonen, Harald J.J., Moonen, Edwin J.C., Maas, Lou, Dallinga, Jan W., Kleinjans, Jos C.S., and de Kok, Theo M.C.M.
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PYRIDINE , *AMINES , *CYTOCHROMES , *ACETYLTRANSFERASES , *GENES , *ENZYMES - Abstract
2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a mutagenic and carcinogenic heterocyclic amine formed during ordinary cooking, and is subsequently metabolically activated by cytochrome P4501A2 (CYP1A2) and N-acetyltransferase 2 (NAT2). Respective genes encoding for these enzymes, display polymorphic distribution in the human population and are thus believed to cause interindividual differences in cancer risk susceptibility. The present study investigated the influence of dietary exposure and CYP1A2 and NAT2 genotypes and phenotypes on differential urinary PhIP excretion levels in 71 human volunteers after consumption of either a high (7.4 ng/g) or low (1.7 ng/g) dose of PhIP. Urinary PhIP excretion levels were found to reflect recent dietary exposure levels, with average levels of 174% (high dose group) and 127% (low dose group), as compared to pre-feed levels. Urinary caffeine metabolite ratios were significantly different between the two NAT2 genotypes, whereas for CYP1A2, the apparent difference in metabolic ratios between the genotypes was statistically non-significant. Significant correlations were firstly found between the CYP1A2-164A→C (CYP1A2*1F) polymorphism and differential urinary PhIP excretion levels. Although the found correlations are driven primarily by a small number of subjects possessing the homozygous variant constellation, the strong influence of this genotype indicates that the CYP1A2*1F polymorphism could play an important role in human cancer risk susceptibility. [Copyright &y& Elsevier]
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- 2004
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7. Development of analytical technology in pharmacogenetic research.
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Daly, Ann K.
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GENETIC research ,GENETIC polymorphisms ,PHENOTYPES ,ENZYMES ,CYTOCHROMES ,ACETYLTRANSFERASES - Abstract
Methods used to determine phenotype and genotype for pharmacogenetic polymorphisms are discussed. Phenotyping is mainly applicable to polymorphisms affecting drug disposition rather than drug response and can involve either direct measurement of enzyme activity or administration of a probe drug followed by measurement of drug and/or metabolite levels. Genotyping is now more widely used than phenotyping and can be used to determine genotype for polymorphisms affecting either drug disposition (for example those in the cytochromes P450 or N-acetyltransferases) or drug response (for example those in drug receptors). Most genotyping for known polymorphisms involves use of the polymerase chain reaction and the wide variety of methods based on this technique that are now used for routine genotyping are discussed in detail. In addition, a range of methods that can be used to detect novel polymorphisms, thereby further increasing understanding of interindividual variability in drug disposition and response, is described. [ABSTRACT FROM AUTHOR]
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- 2004
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8. Dedifferentiation of Primary Hepatocytes is Accompanied with Reorganization of Lipid Metabolism Indicated by Altered Molecular Lipid and miRNA Profiles
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Mostafa, Kiamehr, Laura, Heiskanen, Thomas, Laufer, Aneta, Düsterloh, Mustafa, Kahraman, Reijo, Käkelä, Reijo, Laaksonen, Katriina, Aalto-Setälä, Molecular and Integrative Biosciences Research Programme, Functional Lipidomics Group, Physiology and Neuroscience (-2020), Helsinki Institute of Life Science HiLIFE, Lääketieteen ja terveysteknologian tiedekunta - Faculty of Medicine and Health Technology, and Tampere University
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Male ,EXPRESSION ,Biochemistry & Molecular Biology ,LIVER ,RECEPTOR-ALPHA ,Fatty Acid Elongases ,MICRORNAS ,Chemistry, Multidisciplinary ,Serum Albumin, Human ,HIGH-THROUGHPUT ,Article ,Biokemia, solu- ja molekyylibiologia - Biochemistry, cell and molecular biology ,lcsh:Chemistry ,primary human hepatocytes (PHHs) ,CERAMIDE SYNTHASES ,Acetyltransferases ,Lääketieteen bioteknologia - Medical biotechnology ,Humans ,phospholipids (PLs) ,lcsh:QH301-705.5 ,Cells, Cultured ,mass spectrometry ,Science & Technology ,SPHINGOLIPID METABOLISM ,microRNAs (miRNAs) ,monounsaturated fatty acids (MUFAs) ,polyunsaturated fatty acids (PUFAs) ,dedifferentiation ,GLUCOSE-METABOLISM ,IN-VITRO ,Cell Dedifferentiation ,Middle Aged ,HEPG2 CELLS ,Lipid Metabolism ,Up-Regulation ,Fatty Acid Synthase, Type I ,Chemistry ,lcsh:Biology (General) ,lcsh:QD1-999 ,Physical Sciences ,Hepatocytes ,Cytochromes ,1182 Biochemistry, cell and molecular biology ,lipidomics ,lipids (amino acids, peptides, and proteins) ,sphingolipids (SLs) ,saturated fatty acids (SFAs) ,Life Sciences & Biomedicine ,Stearoyl-CoA Desaturase - Abstract
Aim: Primary human hepatocytes (PHHs) undergo dedifferentiation upon the two-dimensional (2D) culture, which particularly hinders their utility in long-term in vitro studies. Lipids, as a major class of biomolecules, play crucial roles in cellular energy storage, structure, and signaling. Here, for the first time, we mapped the alterations in the lipid profile of the dedifferentiating PHHs and studied the possible role of lipids in the loss of the phenotype of PHHs. Simultaneously, differentially expressed miRNAs associated with changes in the lipids and fatty acids (FAs) of the dedifferentiating PHHs were investigated. Methods: PHHs were cultured in monolayer and their phenotype was monitored morphologically, genetically, and biochemically for five days. The lipid and miRNA profile of the PHHs were analyzed by mass spectrometry and Agilent microarray, respectively. In addition, 24 key genes involved in the metabolism of lipids and FAs were investigated by qPCR. Results: The typical morphology of PHHs was lost from day 3 onward. Additionally, ALB and CYP genes were downregulated in the cultured PHHs. Lipidomics revealed a clear increase in the saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) containing lipids, but a decrease in the polyunsaturated fatty acids (PUFA) containing lipids during the dedifferentiation of PHHs. In line with this, FASN, SCD, ELOVL1, ELOVL3, and ELOVL7 were upregulated but ELOVL2 was downregulated in the dedifferentiated PHHs. Furthermore, differentially expressed miRNAs were identified, and the constantly upregulated miR-27a and miR-21, and downregulated miR-30 may have regulated the synthesis, accumulation and secretion of PHH lipids during the dedifferentiation. Conclusion: Our results showed major alterations in the molecular lipid species profiles, lipid-metabolizing enzyme expression as wells as miRNA profiles of the PHHs during their prolonged culture, which in concert could play important roles in the PHHs&rsquo, loss of phenotype. These findings promote the understanding from the dedifferentiation process and could help in developing optimal culture conditions, which better meet the needs of the PHHs and support their original phenotype.
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- 2019
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