... and 23-CH; (B) expansion of proton–proton TOCSY correlations for 3-CH and 23-CH; (C) expansion of proton–carbon HSQC showing groups having correlation to 3-CH and 23-CH (for details, see text) ... Identification of minor products of vitamin D3 metabolism by P450scc Fig Identification of 20,23-dihydroxyvitamin D3 (A) Expansion of proton–proton COSY correlations for 3-CH and 23-CH; (B) expansion of ... confirms that no hydroxylation occurs in the A-ring The new hydroxylated CH shows correlations in the COSY spectrum to four protons, and analysis of HSQC indicates that these protons belong to...
Ngày tải lên: 18/02/2014, 17:20
... cloned into pGEM-T (Promega), and sequenced on both strands The full-length clone was cloned into pRSETa for bacterial expression of antigen Antigen was expressed by recombinant expression in BL21(DE3) ... cytochrome P450-mediated liver and brain anandamide metabolism Biochem Pharmacol 50, 677–686 22 Strobel HW, Thompson CM & Antonovic L (2001) Cytochromes P450 in brain: Function and significance ... 3,3¢-diaminobenzidine (DAB) staining was granular and confined to the cytoplasm of the cells Based on their size and shape the cells labelled in all brain regions appeared to be neurons Blood vessels were also...
Ngày tải lên: 19/02/2014, 07:20
Tài liệu Báo cáo khóa học: Point mutations associated with insecticide resistance in the Drosophila cytochrome P450 Cyp6a2 enable DDT metabolism doc
... able to hydroxylate testosterone at one position identified as 2b with no significant variation in the specific activity As a consequence, we considered testosterone hydroxylation at the 2b position ... modulated in two variants among five, we can exclude any effect of these mutations on the electron transfer process To elucidate the mechanism by which mutations on the J helix and in the vicinity ... migration in dichloromethane/acetone (4 : 1; v/v), second migration in chloroform/ ethyl acetate/ethanol (40 : 10 : 7; v/v/v)] Cold markers migrated alongside the testosterone metabolites After autoradiography...
Ngày tải lên: 19/02/2014, 12:20
Tài liệu Báo cáo khoa học: Models and mechanisms of O-O bond activation by cytochrome P450 A critical assessment of the potential role of multiple active intermediates in oxidative catalysis doc
... electron largely transferred to O2 in an autoxidative process (Scheme 2) Spontaneous autodecomposition of oxy-cytochrome 2B4 to release ferric pigment and superoxide [37] has been shown to occur ... with residues such as alanine or valine proved to be deleterious to conversion of androgens to estrogens [276] Based on an active site ể FEBS 2004 O-O Bond activation by cytochrome P450 (Eur J Biochem ... above To quantitatively assess the signicance of electron transfer in the transition states of hydroxylation reactions, studies on the regioselectivity of nitroacenaphthene oxygenation were conducted...
Ngày tải lên: 19/02/2014, 16:20
Báo cáo khoa học: Arabidopsis thaliana CYP77A4 is the first cytochrome P450 able to catalyze the epoxidation of free fatty acids in plants potx
... co-expressed with a given bait P450 during plant development, on stress and hormone treatment, and in mutant wild-type comparisons Based on the functional annotation of co-expressed genes, a metabolic ... assessed by future studies of A thaliana mutated in the coding sequence of CYP77A4 Results Selection, cloning and expression of CYP77A4 An approach based on an in silico analysis predicted that CYP77A4 ... Incubations were performed at 27 °C and contained 20 pmol of CYP77A4 They were stopped after 30 by the addition of 20 lL of acetonitrile (containing 0.2% acetic acid) and directly spotted onto TLC...
Ngày tải lên: 07/03/2014, 03:20
Báo cáo khoa học: Inter-flavin electron transfer in cytochrome P450 reductase – effects of solvent and pH identify hidden complexity in mechanism potx
... half-reaction kinetically, a constant ionic strength must be maintained, because the observed rate constants of CPR reduction have been found to signicantly increase with the total ion concentration ... phase; DeLHA and DeLA are the amplitudes of the protonated and deprotonated species, respectively Proton inventory experiments were analysed by plotting the ratio of the rate constant kn, obtained ... compilation ê 2008 FEBS 4541 Electron transfer in cytochrome P450 reductase S Brenner et al CPR [30]) and the second on the four-electron reduction by a second molecule of NADPH ($ and $ 3ặs)1,...
Ngày tải lên: 07/03/2014, 06:20
Báo cáo khoa học: D88A mutant of cytochrome P450nor provides kinetic evidence for direct complex formation with electron donor NADH ppt
... reduction step for P450nor wild-type and mutant enzymes kobs, Observed first-order rate constant for reduction (I formation); kdec, first-order rate constant for spontaneous decomposition of I; ... reaction (one-step reaction; Eqn 6), as the reaction of P450nor is too rapid (more than 1000 s)1 at 10 °C) [7] for an enzymatic reaction in which electron transfer from or to NAD is involved To discriminate ... (electron transfer) reaction (Eqn 5) On the other hand, the possibility cannot be ruled out yet that the electron transfer from NADH to P450nor is carried out in a manner like in a chemical reaction...
Ngày tải lên: 07/03/2014, 15:20
Báo cáo khoa học: Testosterone 1b-hydroxylation by human cytochrome P450 3A4 pdf
... of electron-transfer proteins: recommendations 1989 J Biol Chem 267, 665–677 Dorfman, R., Cook, J.W & Hamilton, J.B (1939) Conversion by the human of the testis hormone, testosterone, into the ... submitted [39] Porcine gonadal P450 19A1 (aromatase) converted testosterone to significant amounts of 1b-hydroxytestosterone, as well as 19-hydroxy- and 19-oxotestosterone and 17b-estradiol [39] ... 40 10 20 Based on total P450 Table Testosterone hydroxylation by various human P450 enzymes Assays were done (in triplicate) with bacterial membranes (ÔbicistronicÕ) containing P450 and NADPH-P450...
Ngày tải lên: 07/03/2014, 16:20
Báo cáo khoa học: Kinetic and binding studies with purified recombinant proteins ferredoxin reductase, ferredoxin and cytochrome P450 comprising the morpholine mono-oxygenase from Mycobacteriumsp. strain HE5 ppt
... couple towards the artificial electron acceptors NBT and cytochrome c were determined spectrophotometrically using an Uvikon 930 spectrophotometer (Kontron, Milton Keynes, UK) NBT reduction was ... iron content of the ferredoxin Fdmor was determined by atom absorption spectroscopy on 1156 B Sielaff and J R Andreesen an AAnalyst 800 (Perkin–Elmer, Boston, MA, USA) using electrothermal atomization ... AW, Cheesman MR, Reid GA, von Wachenfeldt C & Chapman SK (2003) Expression, purification and characterisation of a Bacillus subtilis ferredoxin: a potential electron transfer donor to cytochrome...
Ngày tải lên: 07/03/2014, 16:20
Báo cáo khoa học: The cytochrome P450scc system opens an alternate pathway of vitamin D3 metabolism docx
... Vitamin D is a membrane antioxidant Ability to inhibit iron-dependent lipid peroxidation in liposomes compared to cholesterol, ergosterol and tamoxifen and relevance to anticancer action FEBS Lett 326, ... (1986) Stoichiometry of mitochondrial cytochromes P-450, adrenodoxin and adrenodoxin reductase in adrenal cortex and corpus luteum Implications for membrane organization and gene regulation Eur ... gradient to 100% methanol and 0.1% acetic acid from 25 to 35 min; and 100% methanol and 0.1% acetic acid from 35 to 55 Note the marked disappearance of products 6, and enzymes involved in generation...
Ngày tải lên: 07/03/2014, 21:20
Báo cáo Y học: Baboon cytochrome P450 17a-hydroxylase/17,20-lyase (CYP17) Characterization of the adrenal microsomal and cloned enzymes docx
... baboon and human CYP17 are predominantly conservative with some differences resulting in a change in side chain size and polarity Exon and show the least homology between the baboon and human ... (sense), and 5¢-tatacccgggaagcttttaggtgctaccctcagcctg-3¢ (antisense) were Concentrations of cytochrome P450 and cytochrome b5 in baboon adrenal microsomes The dithionite reduced carbon monoxide ... dichloromethane phase was evaporated under N2 and the dried residue redissolved in methanol prior to HPLC analysis Separation and quantification of steroids Chromatography was performed on a Waters...
Ngày tải lên: 08/03/2014, 09:20
Báo cáo Y học: Substrates modulate the rate-determining step for CO binding in cytochrome P450cam (CYP101) A high-pressure stopped-flow study pdf
... Table 2) and the CO molecule has few or even only one pathway to approach the heme iron where it immediately sticks in the right position for bond formation leading to volume contraction (negative ... dissociation constants [3]: norcamphor (345 lM), norbornane (47 lM), camphane (1.1 lM), 1R-camphor (0.8 lM), 1.7 mM sodium dithionite, values for concentrations correspond to the mixture b The mean ... DHon ¼ DEon + PÆDV # [15] # where DEon is the internal energy of activation which may be assigned to the energy needed to break bonds or other contacts (e.g hydrogen bonds) or to induce a conformational...
Ngày tải lên: 08/03/2014, 23:20
Báo cáo khoa học: Kinetic deuterium isotope effects for 7-alkoxycoumarin O-dealkylation reactions catalyzed by human cytochromes P450 and in liver microsomes Rate-limiting C-H bond breaking in cytochrome P450 1A2 substrate oxidation pdf
... substantial contribution to this particular enzyme activity in liver microsomes, and the question can be raised as to whether the microsomal (and in vivo) rates are limited by reduction and other ... bond and a C-D bond at a single carbon [3] The value obtained from such an experiment can be used as an approximation of the true intrinsic kinetic deuterium isotope effect and for comparison ... reactions under all conditions Some shifting of the oxidations to the alternate 3-hydroxylation reactions occurs with some of the enzymes (with 7-OMe and 7-OEt coumarin), but not to the extent to...
Ngày tải lên: 16/03/2014, 13:20
Báo cáo khoa học: The first cytochrome P450 in ferns Evidence for its involvement in phytoecdysteroid biosynthesis in Polypodium vulgare doc
... dose– response between ketoconazole concentration and E bioconversion in vivo An 80% inhibition of hydroxylase reaction occurred when 17.8 nmol of ketoconazole was applied topically to calli This ... inhibitors used in fungi, plants and mammals to block P450 pathways inhibit E bioconversion in P vulgare calli A dose–response relation between ketoconazole concentration and a decrease in the E to ... separation of membrane proteins solubilized in Triton X-114: application to the purification of plant cytochromes P-450 and b5 Anal Biochem 197, 125–131 40 Andersen MD & Moller BL (1998) Double Triton...
Ngày tải lên: 16/03/2014, 23:20
Báo cáo khoa học: Two CCAAT/enhancer binding protein sites in the cytochrome P4503A1 locus Potencial role in the glucocorticoid response ppt
... receptor, has defined an alternative steroid regulatory pathway [39] However, other critical transcription factors are likely to participate in the organization of the transcription initiation complex ... (2000) Dexamethasone induces pregnane X receptor and retinoid X receptor-a expression in human hepatocytes: synergistic increase of CYP3A4 induction by pregnane X receptor activators Mol Pharmacol ... expression of several transcription factors in the hepatocyte C/EBP concentration was recently shown to vary as a function of the differentiation of long-term human primary hepatocytes in culture [46]...
Ngày tải lên: 17/03/2014, 09:20
Báo cáo khoa học: Key substrate recognition residues in the active site of a plant cytochrome P450, CYP73A1 ppt
... (mean distances between two atoms, mean Phi and Psi values), and their standard deviations The distance cutoff ˚ between two atoms was set to A, except for interblock CB atoms where no cutoff ... with no constraints From each model, Phi and Psi additional constraints for nonconserved residues were derived in order to restrain them in an allowed region of the Ramachandran region DYANA was ... microsomes were used to test for CYP73-independent reactions and to evaluate extraction yields Product elution was monitored by photodiode array detection Retention times of I3C and its oxygenated...
Ngày tải lên: 17/03/2014, 10:20
Báo cáo khoa học: Metabolism of N-methyl-amide by cytochrome P450s Formation and characterization of highly stable carbinol-amide intermediate pdf
... the transition states involved in the elimination reaction Based on reaction conditions, three types of mechanism can be considered: neutral, cationic and anionic Because highly basic conditions ... favorable protonation site of the carbinol-amide is the Ocarbonyl atom (d4) This O-carbonyl protonated intermediate can evolve through a deformylation transition state (d6) leading to O-protonated ... shown) NMR analysis A proton NMR spectrum was recorded in CDCl3 at room temperature on a mixture of M1 and M2, and was analyzed in the p.p.m region characteristic of N-methyl proton resonances of...
Ngày tải lên: 22/03/2014, 16:20
Báo cáo khoa học: Cytochrome P450 metabolizing fatty acids in plants: characterization and physiological roles pptx
... each plant species contains only one CYP703 [37] CYP704B1 and CYP704B2 belong to a conserved and ancient P450 family in moss and seed plants This suggests that reactions catalysed by CYP703 and ... x-hydroxylation, diacid formation x-hydroxylation, diacid formation x-hydroxylation x-hydroxylation x-hydroxylation x-hydroxylation x-hydroxylation x-hydroxylation x-hydroxylation in-chain hydroxylation ... Candida maltosa to grow on media containing aliphatic hydrocarbons as a sole source of carbon and energy (reviewed in [18]) In plants, besides enhancement of FA hydroxylases at the transcriptional...
Ngày tải lên: 22/03/2014, 16:21
Báo cáo khoa học: The role of cytochrome P450 monooxygenases in microbial fatty acid metabolism pdf
... infection, together with other genes regarding the utilization of nonconventional carbon sources [20] These findings suggest that, on the one hand, alkane degradation is required for breaking the plant’s ... oxidation often also mediate subterminal oxidation The corresponding secondary alcohols are oxidized to ketones and a Baeyer–Villiger monooxygenase converts them to esters, which are cleaved to give ... verticilloides and Fusarium proliferatum, both widespread plantpathogens infecting maize and other grains, rendering this mycotoxin a common contaminant of corn Fumonisin is hepatotoxic and nephrotoxic,...
Ngày tải lên: 22/03/2014, 16:21