- Surface-enhanced resonance Raman scattering spectroscopy applied to phytochrome and its model compounds. 1. Biliverdin photoisomers
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The application of surface-enhanced resonance Raman scattering (SERRS) spectroscopy to the analysis of the configuration of biliverdin dimethyl ester (BVDE) is reported. SERRS spectra obtained by adsorption of the compounds onto an electrochemically roughened silver electrode and recorded at 77 K were intense and free of significant photodegradation. The similarity of the SERRS and resonance Raman (RR) spectra obtained under identical conditions suggests that no perturbation of the electronic structure of the BVDE occurs upon interaction with the silver surface, and that the distribution of conformers comprising the BVDE solution is not changed. SERRS spectra of the deuterated and monoprotonated Z,Z,Z isomer are also presented. To investigate the influence of configuration upon the Raman spectrum we have synthesized and purified the E,Z,Z and Z,Z,E isomers of BVDE. Excellent SERRS spectra were obtained from the solutions of the compounds eluted directly from the TLC plates. Comparison of these isomers to the more stable Z,Z,Z isomer reveals differences in frequencies and relative intensities associated with the change in molecular geometry upon isomerization. Most significant is the change in intensity of bands observed at 1255 and at 1245 cm-1, a band that has been previously correlated to changes in conformation of the closely related phycocyanin chromophore.
- Holt,Farrens,Song,Cotton
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- Heme-iron utilization by Leptospira interrogans requires a heme oxygenase and a plastidic-type ferredoxin-NADP+ reductase
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Background Heme oxygenase catalyzes the conversion of heme to iron, carbon monoxide and biliverdin employing oxygen and reducing equivalents. This enzyme is essential for heme-iron utilization and contributes to virulence in Leptospira interrogans. Methods A phylogenetic analysis was performed using heme oxygenases sequences from different organisms including saprophytic and pathogenic Leptospira species. L. interrogans heme oxygenase (LepHO) was cloned, overexpressed and purified. The structural and enzymatic properties of LepHO were analyzed by UV-vis spectrophotometry and 1H NMR. Heme-degrading activity, ferrous iron release and biliverdin production were studied with different redox partners. Results A plastidic type, high efficiently ferredoxin-NADP+ reductase (LepFNR) provides the electrons for heme turnover by heme oxygenase in L. interrogans. This catalytic reaction does not require a ferredoxin. Moreover, LepFNR drives the heme degradation to completeness producing free iron and α-biliverdin as the final products. The phylogenetic divergence between heme oxygenases from saprophytic and pathogenic species supports the functional role of this enzyme in L. interrogans pathogenesis. Conclusions Heme-iron scavenging by LepHO in L. interrogans requires only LepFNR as redox partner. Thus, we report a new substrate of ferredoxin-NADP+ reductases different to ferredoxin and flavodoxin, the only recognized protein substrates of this flavoenzyme to date. The results presented here uncover a fundamental step of heme degradation in L. interrogans. General significance Our findings contribute to understand the heme-iron utilization pathway in Leptospira. Since iron is required for pathogen survival and infectivity, heme degradation pathway may be relevant for therapeutic applications.
- Soldano, Anabel,Yao, Huili,Rivera, Mario,Ceccarelli, Eduardo A.,Catalano-Dupuy, Daniela L.
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p. 3208 - 3217
(2014/12/10)
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- The synthesis of [10-13C]bilirubin IXα
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The total synthesis of [10-13C]bilirubin IXα, the principal waste product of haem degradation, is described. Site specific labelling was accomplished by the Vilsmeier formylation of one of the dipyrrolic fragments using [1-13C]dimethylformamide. The penultimate dehydrohalogenation reaction was complicated by a competing elimination reaction which yielded a bridged biliverdin derivative. [10-13C]bilirubin IXα was prepared in an overall yield of 6% (from the step where 13C was introduced) with quantitative isotopic incorporation.
- Sturrock,Bull,Kirsch
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p. 263 - 274
(2007/10/02)
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- On the Fate of Biliverdin-IIIα-dimethyl Ester Formed by Scrambling During Syntheses of Biliverdin-IXα-dimethyl Ester from Bilirubin
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In the preparations of biliverdin-IXα-dimethyl ester (2b) from bilirubin-IXα (1) the ratio of the XIIIα- and IIIα-isomers 3b and 4b, formed via intermolecular scrambling, should be unity.However, irrespective of the synthetic variant considered, the amount of 4b obtained usually is exceptionally low.This is partly ascribed to a consecutive reaction of 4b in acidic methanol affording the chiral diastereomeric bridged biliverdins 5(a and b) and 6(a and b), respectively. - Keywords: Biliverdin-IIIα; Bridged biliverdins; Bilatrienes
- Krois, Daniel,Lehner, Harald
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p. 575 - 580
(2007/10/02)
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- Chemical Studies on Products Obtained from Verdohemochrome IXα Dimethyl Ester by Treatment with Ammonia under Air
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Verdohemochrome IXα dimethyl ester gave 5-azaprotohemin IX dimethyl ester (2) and six tripyrrin derivatives upon treatment with ammonia under air, followed by methylation.The reaction of 2 with
- Saito, Setsuo,Tamura, Norihiro
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p. 4037 - 4050
(2007/10/02)
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- POLYMER BOUND PYRROLE COMPOUNDS- II. SYNTHESIS AND PROPERTIES OF POLYSTYRENE-BOUND LINEAR TETRAPYRROLE PIGMENTS AND RELATED 5(1H)-PYRROMETHENONES
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The title chromophores have been reversibly and covalently attached to differently functionalized polystyrenes including the α-poly(styrene-co-divinylbenzene), and its desnitro derivate.The influence on the reaction
- Castan, Pilar,Giralt, Ernest,Perez, Juan C.,Ribo, Josef M.,Siscart, Nuria,Trull, Francesc R.
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p. 2593 - 2608
(2007/10/02)
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- Cyclization of Biliverdins to Verdohaemochromes
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Iron(II) octaethylverdohaemochrome was obtained both by cyclization of octaethylbiliverdin in the presence of FeSO4 and pyridine, and by coupled oxidation of octaethylhaemin and ascorbic acid with O2 in the presence of pyridine.The compound obtained by cyclization of biliverdin IXα dimethyl ester was, however, different from that obtained by the methylation of iron(II) protoverdohaemochrome IXα , the product of coupled oxidation of the protohaem in myoglobin.The electronic absorption spectra of the pyridine and tosylmethyl isocyanide (TsCH2NC) complexes, (14) and (15), of the product of cyclization were different from the spectra of the same complexes, (11) and (12), of the product of coupled oxidation.The product of cyclization was reduced to the product of coupled oxidation by sodium dithionite.It is postulated that compounds (14) and (15) are bis(pyridine) and bis(isocyanide) coordination complexes of iron(III) protoverdohaemochrome dimethyl ester.The positions of the maxima in the absorption spectra of compounds (16) and (17), the pyridine and TsCH2NC complexes of both the product of coupled oxidation of mesohaemin dimethyl ester and the product of cyclization of mesobiliverdin dimethyl ester, indicated that these compounds are analogues, not of (11) and (12), but of (14) and (15).Iron(II) azaporphyrins (7) and (13) were prepared by treatment of the corresponding iron(II) oxaporphyrins (5) and (11) with ammonia.
- Saito, Setsuo,Itano, Harvey A.
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- BILE PIGMENT STUDIES - VII NEW SYNTHESES OF BILIVERDIN-IXα DIMETHYL ESTER AND TWO RELATED MONO-VINYL-ETHYL ISOMERS
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Using the recently developed route through di-t-butyl b-bilene-1,19-dicarboxylates, new syntheses of biliverdin-IXα dimethyl ester (1) and two related mono-vinyl-mono-ethyl isomers (2) and (3), are described.The two dihydro-derivatives of (1) are importan
- Smith, Kevin M.,Pandey, Ravindra K.
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p. 1749 - 1754
(2007/10/02)
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- POLYMER BOUND PYRROLE COMPOUNDS. REVERSIBLE ANCHORING OF BILIRUBIN AND BILIVERDIN TO A POLYSTIRENE MATRIX
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Both bilirubin and biliverdin, via their cesium salts, have been covalently attached to an insoluble polystyrene matrix (the so-called Nbb-resin), some chemical transformations have been carried out upon the supported pigments, and the resulting products have been detached by alkaline methanol.
- Giralt, Ernest,Ribo, Josep Ma.,Trull, Francesc R.
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p. 4145 - 4146
(2007/10/02)
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- The Structure of "Photobilirubin"
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Anaerobic irradiation of bilirubin in the region of the main absorption band produces the diastereomers of (Z,E)- and (E,Z)-configurations with high quantum yield.The structure of these "photobilirubins" is proven by a chemical correlation with the corresponding diastereomers of biliverdindimethylester characterised before.Their 1H-NMR spectroscopic features have been recorded and are discussed. - Keywords: (Z,Z)-, (Z,E)- and (E,Z)-Bilirubin; Photobilirubin; Neonatal jaundice; Phototherapy
- Falk, Heinz,Mueller, Norbert,Ratzenhofer, Michael,Winsauer, Karl
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p. 1421 - 1432
(2007/10/02)
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