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Hiroshi Yamazaki - One of the best experts on this subject based on the ideXlab platform.
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induction of human cytochrome p450 3a enzymes in cultured placental cells by thalidomide and relevance to bioactivation and toxicity
Journal of Toxicological Sciences, 2017Co-Authors: Norie Murayama, Kazuyuki Arata, Yasuhiro Kazuki, Norio Shibata, F. Peter Guengerich, Daisuke Satoh, T Harada, Hiroshi YamazakiAbstract:Evidence has been presented for auto-induced human cytochrome P450 3A enzyme involvement in the teratogenicity and clinical outcome of thalidomide due to oxidation to 5-hydroxythalidomide and subsequent metabolic activation in livers. In this study, more relevant human placenta preparations and placental BeWo cells showed low but detectable P450 3A4/5 mRNA expression and drug oxidation activities. Human placental microsomal fractions from three subjects showed detectable midazolam 1´- and 4-Hydroxylation and thalidomide 5-Hydroxylation activities. Human placental BeWo cells, cultured in the recommended media, also indicated detectable midazolam 1´- and 4-Hydroxylation and thalidomide 5-Hydroxylation activities. To reduce any masking effects by endogenous hormones used in the recommended media, induction of P450 3A4/5 mRNA and oxidation activities were measured in placental BeWo cells cultured with a modified medium containing 5% charcoal-stripped fetal bovine serum. Thalidomide significantly induced P450 3A4/5, 2B6, and pregnane X receptor (PXR) mRNA levels 2 to 3-fold, but rifampicin only enhanced P450 3A5 and PXR mRNA under the modified media conditions. Under these modified conditions, thalidomide also significantly induced midazolam 1´-Hydroxylation and thalidomide 5-hydroxylaion activities 3-fold but not bupropion Hydroxylation activity. Taken together, activation of thalidomide to 5-hydroxythalidomide with autoinduction of P450 3A enzymes in human placentas, as well as livers, is suggested in vivo.
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oxidation of r and s omeprazole stereoselectively mediated by liver microsomal cytochrome p450 2c19 enzymes from cynomolgus monkeys and common marmosets
Biochemical Pharmacology, 2016Co-Authors: Shotaro Uehara, Norie Murayama, Masahiro Utoh, Yasuhiro Uno, Mirai Kawano, Takashi Inoue, Erika Sasaki, Hiroshi YamazakiAbstract:Racemic omeprazole has been used for clinically treating gastric acid-related diseases and also as a typical human cytochrome P450 (P450) 2C19 probe substrate in preclinical studies. S-Omeprazole has been developed as a single enantiomer medicine, which has been reported not to be associated with polymorphic human P450 2C19 phenotypes. In this study, 5-Hydroxylation and sulfoxidation activities, with respect to stereoselective R- and S-omeprazole oxidations by liver microsomes from experimental animals including non-human primates and humans, were investigated in vitro. Liver microsomes from humans, cynomolgus monkeys, and mice preferentially mediated R-omeprazole 5-Hydroxylations, however those from marmosets, minipigs, dogs, and rats preferentially mediated S-omeprazole 5-Hydroxylations. High catalytic activities were observed for recombinant human P450 2C19 in R-omeprazole 5-hydroxlations, cynomolgus monkey P450 2C19 in both R- and S-omeprazole 5-hydroxlations, and marmoset P450 2C19 in S-omeprazole 5-hydroxlations. On the other hand, human, cynomolgus monkey, and marmoset P450 3A enzymes preferentially mediated S-omeprazole sulfoxidations. Correlation and kinetic analyses revealed a high affinity of polymorphic cynomolgus monkey and marmoset liver microsomal P450 2C19 enzymes with respect to R- and S-omeprazole 5-Hydroxylations, respectively, and a high capacity of cynomolgus monkey and marmoset liver microsomal P450 3A4 for omeprazole 5-Hydroxylations and sulfoxidations. R-and S-omeprazole 5-Hydroxylation activities in cynomolgus monkey and marmoset liver microsomes were significantly different among wild-type, heterozygous, and homozygous animals genotyped for cynomolgus monkey P450 2C19 p.[(Phe100Asn; Ala103Val; Ile112Leu)] and for marmoset P450 2C19 p.[(Phe7Leu; Ser254Leu; Ile469Thr)], respectively. The results of this study demonstrate polymorphic cynomolgus monkey and marmoset P450 2C19-dependent omeprazole oxidation activities with individual variations similar to humans.
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monkey liver cytochrome p450 2c19 is involved in r and s warfarin 7 Hydroxylation
Biochemical Pharmacology, 2012Co-Authors: Yoshio Hosoi, Norie Murayama, Makiko Shimizu, Masahiro Utoh, Yasuhiro Uno, Hideki Fujino, Mitsunori Shukuya, Kazuhide Iwasaki, Hiroshi YamazakiAbstract:Abstract Cynomolgus monkeys are widely used as primate models in preclinical studies. However, some differences are occasionally seen between monkeys and humans in the activities of cytochrome P450 enzymes. R - and S -warfarin are model substrates for stereoselective oxidation in humans. In this current research, the activities of monkey liver microsomes and 14 recombinantly expressed monkey cytochrome P450 enzymes were analyzed with respect to R - and S -warfarin 6- and 7-Hydroxylation. Monkey liver microsomes efficiently mediated both R - and S -warfarin 7-Hydroxylation, in contrast to human liver microsomes, which preferentially catalyzed S -warfarin 7-Hydroxylation. R -Warfarin 7-Hydroxylation activities in monkey liver microsomes were not inhibited by α-naphthoflavone or ketoconazole, and were roughly correlated with P450 2C19 levels and flurbiprofen 4-Hydroxylation activities in microsomes from 20 monkey livers. In contrast, S -warfarin 7-Hydroxylation activities were not correlated with the four marker drug oxidation activities used. Among the 14 recombinantly expressed monkey P450 enzymes tested, P450 2C19 had the highest activities for R - and S -warfarin 7-Hydroxylations. Monkey P450 3A4 and 3A5 slowly mediated R - and S -warfarin 6-Hydroxylations. Kinetic analysis revealed that monkey P450 2C19 had high V max and low K m values for R -warfarin 7-Hydroxylation, comparable to those for monkey liver microsomes. Monkey P450 2C19 also mediated S -warfarin 7-Hydroxylation with V max and V max / K m values comparable to those for recombinant human P450 2C9. R -warfarin could dock favorably into monkey P450 2C19 modeled. These results collectively suggest high activities for monkey liver P450 2C19 toward R - and S -warfarin 6- and 7-Hydroxylation in contrast to the saturation kinetics of human P450 2C9-mediated S -warfarin 7-Hydroxylation.
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involvement of human cytochrome p450 2b6 in the ω and 4 Hydroxylation of the anesthetic agent propofol
Xenobiotica, 2007Co-Authors: Norie Murayama, Masafumi Minoshima, F. Peter Guengerich, Makiko Shimizu, Hiroshi YamazakiAbstract:Human liver microsomal cytochrome P450s (P450s or CYP) involved in the oxidative biotransformation of the anesthetic agent propofol were investigated. Of six cDNA-expressed human P450 enzymes tested, CYP2B6 and CYP1A2, followed by CYP3A4, had high catalytic activities at a 20 µM propofol concentration, corresponding to clinical plasma levels. Km and kcat values for propofol ω- and 4-hydroxyation were 27 µM and 21 nmol ω-hydroxypropofol formed/min/nmol CYP2B6 and 30 µM and 42 nmol 4-hydroxypropofol formed/min/nmol CYP2B6, respectively. CYP2B6 expressed in HepG2 cells also effectively catalyzed propofol ω- and 4-Hydroxylation. In a panel of individual human liver microsomes, propofol ω- and 4-Hydroxylation activities (at the substrate concentration of 20 µM) were highly correlated with CYP2B6 contents, and moderately with CYP3A4 contents. Anti-CYP2B6 antibody inhibited both ω- and 4-Hydroxylation activities in human liver samples that contained relatively high levels of CYP2B6, whereas α-naphthoflavone and ...
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activities of rat cytochrome p450 3a and 2c isoforms are increased in vivo by magnesium sulfate as evidenced by enhanced oxidation of bupivacaine and testosterone in liver microsomes
Drug Metabolism and Pharmacokinetics, 2006Co-Authors: Miwako Saito, Makiko Shimizu, Hiroshi Yamazaki, Toshiyuki Okutomi, Yoshiaki Matsumoto, Sumio HokaAbstract:Summary: We previously reported that magnesium sulfate (MgSO 4 ) increases the threshold dose of bupivacaine in inducing seizure in rats. Cytochrome P450 (P450) isoforms involved in the biotransformation of bupivacaine to three oxidative metabolites and the effects of MgSO 4 in vivo on the P450 activities in rats were investigated. Of six cDNA-expressed rat P450 isoforms tested, CYP3A2 and CYP2C11 had high rates for N -debutlylation and 3′-Hydroxylation of bupivacaine, respectively. The liver microsomes prepared from male rats pretreated with intravenous administration of MgSO 4 (a bolus dose of 25 mg/kg, followed by infusion of 2.0 mg/kg/min for 6 h) showed increased V max values for N -debutylation and 3′-hydroxylaiton of bupivacaine compared to the liver microsomes from control rats. Administration of MgSO 4 also increased the activities of testosterone 6 β - and 16 α -Hydroxylation. Although the level of expression of CYP3A and CYP2C isoforms in the liver microsomes were unchanged, NADPH-P450 reductase and cytochrome b 5 were found to be induced by intravenous administration of MgSO 4 . These results suggest that CYP3A and CYP2C isoforms are activated by MgSO 4 in vivo as a consequence of enhanced microsomal electron transfer due to induction of NADPH-P450 reductase and cytochrome b 5 , leading to the increased metabolism and clearance of bupivacaine.
Christopher J. Schofield - One of the best experts on this subject based on the ideXlab platform.
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2 oxoglutarate dependent oxygenases
Annual Review of Biochemistry, 2015Co-Authors: Md Saiful Islam, Rasheduzzaman Chowdhury, Thomas M Leissing, Richard J Hopkinson, Christopher J. SchofieldAbstract:2-Oxoglutarate (2OG)-dependent oxygenases (2OGXs) catalyze a remarkably diverse range of oxidative reactions. In animals, these comprise Hydroxylations and N-demethylations proceeding via Hydroxylation; in plants and microbes, they catalyze a wider range including ring formations, rearrangements, desaturations, and halogenations. The catalytic flexibility of 2OGXs is reflected in their biological functions. After pioneering work identified the roles of 2OGXs in collagen biosynthesis, research revealed they also function in plant and animal development, transcriptional regulation, nucleic acid modification/repair, fatty acid metabolism, and secondary metabolite biosynthesis, including of medicinally important antibiotics. In plants, 2OGXs are important agrochemical targets and catalyze herbicide degradation. Human 2OGXs, particularly those regulating transcription, are current therapeutic targets for anemia and cancer. Here, we give an overview of the biochemistry of 2OGXs, providing examples linking to biological function, and outline how knowledge of their enzymology is being exploited in medicine, agrochemistry, and biocatalysis.
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factor inhibiting hypoxia inducible factor fih catalyses the post translational Hydroxylation of histidinyl residues within ankyrin repeat domains
FEBS Journal, 2011Co-Authors: Ming Yang, Rasheduzzaman Chowdhury, Timothy D W Claridge, Michael A Mcdonough, Benedikt M Kessler, Peter J Ratcliffe, Refaat B Hamed, Matthew E Cockman, Christopher J. SchofieldAbstract:Factor-inhibiting hypoxia-inducible factor (FIH) is an Fe(II)/2-oxoglutarate-dependent dioxygenase that acts as a negative regulator of the hypoxia-inducible factor (HIF) by catalysing β-Hydroxylation of an asparaginyl residue in its C-terminal transcriptional activation domain (CAD). In addition to the hypoxia-inducible factor C-terminal transcriptional activation domain (HIF-CAD), FIH also catalyses asparaginyl Hydroxylation of many ankyrin repeat domain-containing proteins, revealing a broad sequence selectivity. However, there are few reports on the selectivity of FIH for the Hydroxylation of specific residues. Here, we report that histidinyl residues within the ankyrin repeat domain of tankyrase-2 can be hydroxylated by FIH. NMR and crystallographic analyses show that the histidinyl Hydroxylation occurs at the β-position. The results further expand the scope of FIH-catalysed Hydroxylations. Database The coordinates for the structure have been deposited in the Protein Data Bank in Europe (PDBe; http://www.ebi.ac.uk/pdbe) under accession code 2y0i
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physiological and biochemical aspects of Hydroxylations and demethylations catalyzed by human 2 oxoglutarate oxygenases
Trends in Biochemical Sciences, 2011Co-Authors: Christoph Loenarz, Christopher J. SchofieldAbstract:Pioneering work in the 1960s defined prolyl and lysyl Hydroxylations as physiologically important oxygenase-catalyzed modifications in collagen biosynthesis; subsequent studies demonstrated that extracellular epidermal growth factor-like domains were hydroxylated at aspartyl and asparaginyl residues. More recent work on the hypoxia-sensing mechanism in animals has shown that prolyl and asparaginyl Hydroxylation of the hypoxia-inducible transcription factor play central roles in sensing hypoxia, by regulating protein–protein interactions in an oxygen-dependent manner. The collective results imply that protein Hydroxylation is more common than previously perceived. Most protein hydroxylases employ Fe(II) as a cofactor, and 2-oxoglutarate and oxygen as co-substrates. Related enzymes catalyze the demethylation of N ɛ -methyl lysine residues in histones and of N -methylated nucleic acids, as well as Hydroxylation of 5-methyl cytosine in DNA and 5-methoxycarbonylmethyluridine at the wobble position of tRNA. The combination of new molecular biological and analytical techniques is likely to reveal further roles for oxygenase-mediated modifications to biomacromolecules.
Norie Murayama - One of the best experts on this subject based on the ideXlab platform.
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induction of human cytochrome p450 3a enzymes in cultured placental cells by thalidomide and relevance to bioactivation and toxicity
Journal of Toxicological Sciences, 2017Co-Authors: Norie Murayama, Kazuyuki Arata, Yasuhiro Kazuki, Norio Shibata, F. Peter Guengerich, Daisuke Satoh, T Harada, Hiroshi YamazakiAbstract:Evidence has been presented for auto-induced human cytochrome P450 3A enzyme involvement in the teratogenicity and clinical outcome of thalidomide due to oxidation to 5-hydroxythalidomide and subsequent metabolic activation in livers. In this study, more relevant human placenta preparations and placental BeWo cells showed low but detectable P450 3A4/5 mRNA expression and drug oxidation activities. Human placental microsomal fractions from three subjects showed detectable midazolam 1´- and 4-Hydroxylation and thalidomide 5-Hydroxylation activities. Human placental BeWo cells, cultured in the recommended media, also indicated detectable midazolam 1´- and 4-Hydroxylation and thalidomide 5-Hydroxylation activities. To reduce any masking effects by endogenous hormones used in the recommended media, induction of P450 3A4/5 mRNA and oxidation activities were measured in placental BeWo cells cultured with a modified medium containing 5% charcoal-stripped fetal bovine serum. Thalidomide significantly induced P450 3A4/5, 2B6, and pregnane X receptor (PXR) mRNA levels 2 to 3-fold, but rifampicin only enhanced P450 3A5 and PXR mRNA under the modified media conditions. Under these modified conditions, thalidomide also significantly induced midazolam 1´-Hydroxylation and thalidomide 5-hydroxylaion activities 3-fold but not bupropion Hydroxylation activity. Taken together, activation of thalidomide to 5-hydroxythalidomide with autoinduction of P450 3A enzymes in human placentas, as well as livers, is suggested in vivo.
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oxidation of r and s omeprazole stereoselectively mediated by liver microsomal cytochrome p450 2c19 enzymes from cynomolgus monkeys and common marmosets
Biochemical Pharmacology, 2016Co-Authors: Shotaro Uehara, Norie Murayama, Masahiro Utoh, Yasuhiro Uno, Mirai Kawano, Takashi Inoue, Erika Sasaki, Hiroshi YamazakiAbstract:Racemic omeprazole has been used for clinically treating gastric acid-related diseases and also as a typical human cytochrome P450 (P450) 2C19 probe substrate in preclinical studies. S-Omeprazole has been developed as a single enantiomer medicine, which has been reported not to be associated with polymorphic human P450 2C19 phenotypes. In this study, 5-Hydroxylation and sulfoxidation activities, with respect to stereoselective R- and S-omeprazole oxidations by liver microsomes from experimental animals including non-human primates and humans, were investigated in vitro. Liver microsomes from humans, cynomolgus monkeys, and mice preferentially mediated R-omeprazole 5-Hydroxylations, however those from marmosets, minipigs, dogs, and rats preferentially mediated S-omeprazole 5-Hydroxylations. High catalytic activities were observed for recombinant human P450 2C19 in R-omeprazole 5-hydroxlations, cynomolgus monkey P450 2C19 in both R- and S-omeprazole 5-hydroxlations, and marmoset P450 2C19 in S-omeprazole 5-hydroxlations. On the other hand, human, cynomolgus monkey, and marmoset P450 3A enzymes preferentially mediated S-omeprazole sulfoxidations. Correlation and kinetic analyses revealed a high affinity of polymorphic cynomolgus monkey and marmoset liver microsomal P450 2C19 enzymes with respect to R- and S-omeprazole 5-Hydroxylations, respectively, and a high capacity of cynomolgus monkey and marmoset liver microsomal P450 3A4 for omeprazole 5-Hydroxylations and sulfoxidations. R-and S-omeprazole 5-Hydroxylation activities in cynomolgus monkey and marmoset liver microsomes were significantly different among wild-type, heterozygous, and homozygous animals genotyped for cynomolgus monkey P450 2C19 p.[(Phe100Asn; Ala103Val; Ile112Leu)] and for marmoset P450 2C19 p.[(Phe7Leu; Ser254Leu; Ile469Thr)], respectively. The results of this study demonstrate polymorphic cynomolgus monkey and marmoset P450 2C19-dependent omeprazole oxidation activities with individual variations similar to humans.
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monkey liver cytochrome p450 2c19 is involved in r and s warfarin 7 Hydroxylation
Biochemical Pharmacology, 2012Co-Authors: Yoshio Hosoi, Norie Murayama, Makiko Shimizu, Masahiro Utoh, Yasuhiro Uno, Hideki Fujino, Mitsunori Shukuya, Kazuhide Iwasaki, Hiroshi YamazakiAbstract:Abstract Cynomolgus monkeys are widely used as primate models in preclinical studies. However, some differences are occasionally seen between monkeys and humans in the activities of cytochrome P450 enzymes. R - and S -warfarin are model substrates for stereoselective oxidation in humans. In this current research, the activities of monkey liver microsomes and 14 recombinantly expressed monkey cytochrome P450 enzymes were analyzed with respect to R - and S -warfarin 6- and 7-Hydroxylation. Monkey liver microsomes efficiently mediated both R - and S -warfarin 7-Hydroxylation, in contrast to human liver microsomes, which preferentially catalyzed S -warfarin 7-Hydroxylation. R -Warfarin 7-Hydroxylation activities in monkey liver microsomes were not inhibited by α-naphthoflavone or ketoconazole, and were roughly correlated with P450 2C19 levels and flurbiprofen 4-Hydroxylation activities in microsomes from 20 monkey livers. In contrast, S -warfarin 7-Hydroxylation activities were not correlated with the four marker drug oxidation activities used. Among the 14 recombinantly expressed monkey P450 enzymes tested, P450 2C19 had the highest activities for R - and S -warfarin 7-Hydroxylations. Monkey P450 3A4 and 3A5 slowly mediated R - and S -warfarin 6-Hydroxylations. Kinetic analysis revealed that monkey P450 2C19 had high V max and low K m values for R -warfarin 7-Hydroxylation, comparable to those for monkey liver microsomes. Monkey P450 2C19 also mediated S -warfarin 7-Hydroxylation with V max and V max / K m values comparable to those for recombinant human P450 2C9. R -warfarin could dock favorably into monkey P450 2C19 modeled. These results collectively suggest high activities for monkey liver P450 2C19 toward R - and S -warfarin 6- and 7-Hydroxylation in contrast to the saturation kinetics of human P450 2C9-mediated S -warfarin 7-Hydroxylation.
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involvement of human cytochrome p450 2b6 in the ω and 4 Hydroxylation of the anesthetic agent propofol
Xenobiotica, 2007Co-Authors: Norie Murayama, Masafumi Minoshima, F. Peter Guengerich, Makiko Shimizu, Hiroshi YamazakiAbstract:Human liver microsomal cytochrome P450s (P450s or CYP) involved in the oxidative biotransformation of the anesthetic agent propofol were investigated. Of six cDNA-expressed human P450 enzymes tested, CYP2B6 and CYP1A2, followed by CYP3A4, had high catalytic activities at a 20 µM propofol concentration, corresponding to clinical plasma levels. Km and kcat values for propofol ω- and 4-hydroxyation were 27 µM and 21 nmol ω-hydroxypropofol formed/min/nmol CYP2B6 and 30 µM and 42 nmol 4-hydroxypropofol formed/min/nmol CYP2B6, respectively. CYP2B6 expressed in HepG2 cells also effectively catalyzed propofol ω- and 4-Hydroxylation. In a panel of individual human liver microsomes, propofol ω- and 4-Hydroxylation activities (at the substrate concentration of 20 µM) were highly correlated with CYP2B6 contents, and moderately with CYP3A4 contents. Anti-CYP2B6 antibody inhibited both ω- and 4-Hydroxylation activities in human liver samples that contained relatively high levels of CYP2B6, whereas α-naphthoflavone and ...
Eiji Itagaki - One of the best experts on this subject based on the ideXlab platform.
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purification and properties of cytochrome p 450 p 450lun catalyzing steroid 11β Hydroxylation in curvularia lunata
Biochimica et Biophysica Acta, 1993Co-Authors: Kenzi Suzuki, Kenichiro Sanga, Yoko Chikaoka, Eiji ItagakiAbstract:Addition of 11-deoxycortisol to the culture medium of Curvularia lunata induced the increase of cytochrome P-450 content and steroid 11 beta-hydroxylase activity. The enzyme in cell-free extract produces cortisol from 11-deoxycortisol in the presence of NADPH and O2. The enzyme was partially stabilized by glycerol, 11-deoxycortisol, GSH and PMSF. The Hydroxylation activity was strongly inhibited by carbon monooxide and sulfhydryl reagents. Cytochrome P-450 located on the microsomal fraction was solubilized with Triton X-100 and sodium cholate and purified to apparent homogeneity by column chromatography. The purified cytochrome P-450 (P-450lun) has a molecular mass of 60 kDa and exhibits the absorption maximum at 392 nm in the spectrum of oxidized form in the presence of 11-deoxycortisol. The reduced CO difference spectrum has a maximal peak at 448 nm. 11 beta-Hydroxylation of 11-deoxycortisol was reconstituted by cytochrome P-450lun, C. lunata NADPH-cytochrome P-450 reductase and DLPC in the presence of NADPH and O2 with a turnover number of 207 nmol/min per nmol of cytochrome P-450. The reductase and DLPC could be partially replaced with the enzyme purified from yeast or pig testis microsome and lipids purified from C. lunata, respectively. P-450lun catalyzes bifunctionally 11 beta- and 14 alpha-Hydroxylations of 11-deoxycortisol. Deoxycorticosterone, progesterone, androstenedione and testosterone are hydroxylated in the similar manner.
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purification and properties of cytochrome p 450 p 450lun catalyzing steroid 11β Hydroxylation in curvularia lunata
Biochimica et Biophysica Acta, 1993Co-Authors: Kenzi Suzuki, Kenichiro Sanga, Yoko Chikaoka, Eiji ItagakiAbstract:Abstract Addition of 11-deoxycortisol to the culture medium of Curvularia lunata induced the increase of cytochrome P -450 content and steroid 11β-hydroxylase activity. The enzyme in cell-free extract produces cortisol from 11-deoxycortisol in the presence of NADPH and O 2 . The enzyme was partially stabilized by glycerol, 11-deoxycortisol, GSH and PMSF. The Hydroxylation activity was strongly inhibited by carbon monooxid and sulfhydryl reagents. Cytochrome P -450 located on the microsomal fraction was solubilized with Triton X-100 and sodium cholate and purified to apparent homogeneity by column chromatography. The purified cytochrome P -450 ( P -450 lun ) has a molecular mass of 60 kDa and exhibits the absorption maxium at 392 nm in the spectrum of oxidized form in the presence of 11-deoxycortisol. The reduced CO difference spectrum has a maximal peak at 448 nm. 11β-Hydroxylation of 11-deoxycortisol was reconstituted by cytochrome P -450 lun , C. lunata NADPH-cytochrome P -450 reductase and DLPC in the presence of NADPH and O 2 with a turnover number of 207 nmol/min per nmol of cytochrome P -450. The reductase and DLPC could be partially replaced with the enzyme purified from yeast or pig testis microsome and lipids purified from C. lunata , respectively. P -450 lun catalyzes bifunctionally 11β- and 14α-Hydroxylations of 11-deoxycortisol. Deoxycorticosterone, progesterone, androstenedione and testosterone are hydroxylated in the similar manner.
Makiko Shimizu - One of the best experts on this subject based on the ideXlab platform.
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monkey liver cytochrome p450 2c19 is involved in r and s warfarin 7 Hydroxylation
Biochemical Pharmacology, 2012Co-Authors: Yoshio Hosoi, Norie Murayama, Makiko Shimizu, Masahiro Utoh, Yasuhiro Uno, Hideki Fujino, Mitsunori Shukuya, Kazuhide Iwasaki, Hiroshi YamazakiAbstract:Abstract Cynomolgus monkeys are widely used as primate models in preclinical studies. However, some differences are occasionally seen between monkeys and humans in the activities of cytochrome P450 enzymes. R - and S -warfarin are model substrates for stereoselective oxidation in humans. In this current research, the activities of monkey liver microsomes and 14 recombinantly expressed monkey cytochrome P450 enzymes were analyzed with respect to R - and S -warfarin 6- and 7-Hydroxylation. Monkey liver microsomes efficiently mediated both R - and S -warfarin 7-Hydroxylation, in contrast to human liver microsomes, which preferentially catalyzed S -warfarin 7-Hydroxylation. R -Warfarin 7-Hydroxylation activities in monkey liver microsomes were not inhibited by α-naphthoflavone or ketoconazole, and were roughly correlated with P450 2C19 levels and flurbiprofen 4-Hydroxylation activities in microsomes from 20 monkey livers. In contrast, S -warfarin 7-Hydroxylation activities were not correlated with the four marker drug oxidation activities used. Among the 14 recombinantly expressed monkey P450 enzymes tested, P450 2C19 had the highest activities for R - and S -warfarin 7-Hydroxylations. Monkey P450 3A4 and 3A5 slowly mediated R - and S -warfarin 6-Hydroxylations. Kinetic analysis revealed that monkey P450 2C19 had high V max and low K m values for R -warfarin 7-Hydroxylation, comparable to those for monkey liver microsomes. Monkey P450 2C19 also mediated S -warfarin 7-Hydroxylation with V max and V max / K m values comparable to those for recombinant human P450 2C9. R -warfarin could dock favorably into monkey P450 2C19 modeled. These results collectively suggest high activities for monkey liver P450 2C19 toward R - and S -warfarin 6- and 7-Hydroxylation in contrast to the saturation kinetics of human P450 2C9-mediated S -warfarin 7-Hydroxylation.
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involvement of human cytochrome p450 2b6 in the ω and 4 Hydroxylation of the anesthetic agent propofol
Xenobiotica, 2007Co-Authors: Norie Murayama, Masafumi Minoshima, F. Peter Guengerich, Makiko Shimizu, Hiroshi YamazakiAbstract:Human liver microsomal cytochrome P450s (P450s or CYP) involved in the oxidative biotransformation of the anesthetic agent propofol were investigated. Of six cDNA-expressed human P450 enzymes tested, CYP2B6 and CYP1A2, followed by CYP3A4, had high catalytic activities at a 20 µM propofol concentration, corresponding to clinical plasma levels. Km and kcat values for propofol ω- and 4-hydroxyation were 27 µM and 21 nmol ω-hydroxypropofol formed/min/nmol CYP2B6 and 30 µM and 42 nmol 4-hydroxypropofol formed/min/nmol CYP2B6, respectively. CYP2B6 expressed in HepG2 cells also effectively catalyzed propofol ω- and 4-Hydroxylation. In a panel of individual human liver microsomes, propofol ω- and 4-Hydroxylation activities (at the substrate concentration of 20 µM) were highly correlated with CYP2B6 contents, and moderately with CYP3A4 contents. Anti-CYP2B6 antibody inhibited both ω- and 4-Hydroxylation activities in human liver samples that contained relatively high levels of CYP2B6, whereas α-naphthoflavone and ...
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activities of rat cytochrome p450 3a and 2c isoforms are increased in vivo by magnesium sulfate as evidenced by enhanced oxidation of bupivacaine and testosterone in liver microsomes
Drug Metabolism and Pharmacokinetics, 2006Co-Authors: Miwako Saito, Makiko Shimizu, Hiroshi Yamazaki, Toshiyuki Okutomi, Yoshiaki Matsumoto, Sumio HokaAbstract:Summary: We previously reported that magnesium sulfate (MgSO 4 ) increases the threshold dose of bupivacaine in inducing seizure in rats. Cytochrome P450 (P450) isoforms involved in the biotransformation of bupivacaine to three oxidative metabolites and the effects of MgSO 4 in vivo on the P450 activities in rats were investigated. Of six cDNA-expressed rat P450 isoforms tested, CYP3A2 and CYP2C11 had high rates for N -debutlylation and 3′-Hydroxylation of bupivacaine, respectively. The liver microsomes prepared from male rats pretreated with intravenous administration of MgSO 4 (a bolus dose of 25 mg/kg, followed by infusion of 2.0 mg/kg/min for 6 h) showed increased V max values for N -debutylation and 3′-hydroxylaiton of bupivacaine compared to the liver microsomes from control rats. Administration of MgSO 4 also increased the activities of testosterone 6 β - and 16 α -Hydroxylation. Although the level of expression of CYP3A and CYP2C isoforms in the liver microsomes were unchanged, NADPH-P450 reductase and cytochrome b 5 were found to be induced by intravenous administration of MgSO 4 . These results suggest that CYP3A and CYP2C isoforms are activated by MgSO 4 in vivo as a consequence of enhanced microsomal electron transfer due to induction of NADPH-P450 reductase and cytochrome b 5 , leading to the increased metabolism and clearance of bupivacaine.
