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Activity of cytochromes P450 1A1, 1A2 and 3A4 expressed in eukaryotic and prokaryotic systems
Indra, Radek ; Stiborová, Marie (advisor) ; Mizerovská, Jana (referee)
Cytochromes P450 (CYP) are a superfamily of heme proteins distributed widely throughout nature, involved in metabolism of a broad variety of substrates and catalyzing a variety of interesting chemical reactions. They play a central role in metabolism of chemotherapeutic agents. Several prodrug antitumor agents have been found as CYP substrates. Ellipticine, an alkaloid found in Apocynaceae plants, is an example of such type of pro-drug. Here, we investigate the efficiencies of human recombinant CYPs expressed in eukaryotic and prokaryotic expression systems, namely in SupersomesTM , microsomes isolated from insect cells transfected with baculovirus construct containing cDNA of human CYP1A1, 1A2 and 3A4 with NADPH:CYP reductase or in Bactosomes, the membrane fraction of E. coli transfected with cDNA of the same human CYP enzymes and NADPH:CYP reductase to oxidize their marker substrates and ellipticine. Cytochrome b5, an aditional component of the mixed function oxidase system, which metabolize xenobiotics was also expressed in some of the systems. The results found in this work demonstrate that human CYP1A1, 1A2 or 3A4 expressed in both eukaryotic and procaryotic systems oxidize their marker substrates (EROD for CYP1A1/2, MROD for CYP1A2 and testosterone 6β-hydroxylation for CYP3A4). They also oxidize...
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Study on metabolism of 3-aminobenzanthrone and induction of biotransformation enzymes
Mizerovská, Jana ; Stiborová, Marie (advisor) ; Mareš, Jaroslav (referee) ; Hýsková, Veronika (referee)
CHARLES UNIVERSITY IN PRAGUE FACULTY OF SCIENCE DEPARTMENT OF BIOCHEMISTRY Study on metabolism of 3-aminobenzanthrone and induction of biotransformation enzymes Summary of PhD Thesis RNDr. Jana Mizerovská Supervisor: Prof. RNDr. Marie Stiborová, DrSc. Prague 2010 RNDr. Jana Mizerovská Introduction 1 INTRODUCTION 3-Nitrobenzanthron, precursor of 3-ABA The nitroaromatic 3-nitrobenzanthrone (3-nitro-7H-benz de anthracen-7-one, 3-NBA) occurs in diesel exhaust and in airborne particulate matter(8, 9, 14) . 3-NBA is most likely formed during the atmospheric reaction of benzanthrone with nitrogen oxides, especially in the presence of ozone, or during imperfect burning of diesel. 3-NBA exhibits extremely high mutagenic activity(9, 14) and is also a genotoxic carcinogen causing lung tumors in rats(14) . 3-NBA is also evaluated to be a potential carcinogen for humans(14, 1, 9, 19) . The genotoxicity of 3-NBA was documented by the detection of specific 3-NBA-derived DNA adducts in vitro, in human cell lines and also in vivo in rats and mice(12, 13, 15, 2) . The predominant DNA adducts formed by 3-NBA after its metabolic activation by reduction of the nitro group are 2-(2'-deoxyguanosin-N2 -yl)-3- aminobenzanthrone and N-(2'-deoxyguanosin-8-yl)-3-aminobenzanthrone(9, 14) and these are most probably responsible for the...
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