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[PMID]:28745873
[Au] Autor:Nauser T; Gebicki JM
[Ad] Endereço:Department of Chemistry and Applied Biosciences, Swiss Federal Institute of Technology , Zurich CH8093, Switzerland.
[Ti] Título:Physiological Concentrations of Ascorbate Cannot Prevent the Potentially Damaging Reactions of Protein Radicals in Humans.
[So] Source:Chem Res Toxicol;30(9):1702-1710, 2017 09 18.
[Is] ISSN:1520-5010
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The principal initial biological targets of free radicals formed under conditions of oxidative stress are the proteins. The most common products of the interaction are carbon-centered alkyl radicals which react rapidly with oxygen to form peroxyl radicals and hydroperoxides. All these species are reactive, capable of propagating the free radical damage to enzymes, nucleic acids, lipids, and endogenous antioxidants, leading finally to the pathologies associated with oxidative stress. The best chance of preventing this chain of damage is in early repair of the protein radicals by antioxidants. Estimate of the effectiveness of the physiologically significant antioxidants requires knowledge of the antioxidant tissue concentrations and rate constants of their reaction with protein radicals. Previous studies by pulse radiolysis have shown that only ascorbate can repair the Trp and Tyr protein radicals before they form peroxyl radicals under physiological concentrations of oxygen. We have now extended this work to other protein C-centered radicals generated by hydroxyl radicals because these and many other free radicals formed under oxidative stress can produce secondary radicals on virtually any amino acid residue. Pulse radiolysis identified two classes of rate constants for reactions of protein radicals with ascorbate, a faster one in the range (9-60) × 10 M s and a slow one with a range of (0.5-2) × 10 M s . These results show that ascorbate can prevent further reactions of protein radicals only in the few human tissues where its concentration exceeds about 2.5 mM.
[Mh] Termos MeSH primário: Ácido Ascórbico/química
Radicais Livres/química
Proteínas/química
[Mh] Termos MeSH secundário: Raios gama
Seres Humanos
Insulina/química
Muramidase/química
Óxidos de Nitrogênio/química
Radiólise de Impulso
Albumina Sérica/química
Espectrofotometria Ultravioleta
Triptofano/química
Tirosina/química
[Pt] Tipo de publicação:JOURNAL ARTICLE; RESEARCH SUPPORT, NON-U.S. GOV'T
[Nm] Nome de substância:
0 (Free Radicals); 0 (Insulin); 0 (Nitrogen Oxides); 0 (Proteins); 0 (Serum Albumin); 42HK56048U (Tyrosine); 8DUH1N11BX (Tryptophan); EC 3.2.1.17 (Muramidase); PQ6CK8PD0R (Ascorbic Acid)
[Em] Mês de entrada:1709
[Cu] Atualização por classe:180127
[Lr] Data última revisão:
180127
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170727
[St] Status:MEDLINE
[do] DOI:10.1021/acs.chemrestox.7b00160


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[PMID]:28939102
[Au] Autor:Nauser T; Gebicki JM
[Ad] Endereço:Laboratorium für Anorganische Chemie, Departement für Chemie und Angewandte Biowissenschaften, Eidgenössische Technische Hochschule (ETH) Zürich, CH - 8093 Zürich, Switzerland. Electronic address: nauser@inorg.chem.ethz.ch.
[Ti] Título:Reaction rates of glutathione and ascorbate with alkyl radicals are too slow for protection against protein peroxidation in vivo.
[So] Source:Arch Biochem Biophys;633:118-123, 2017 Nov 01.
[Is] ISSN:1096-0384
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:Reaction kinetics of amino acid and peptide alkyl radicals with GSH and ascorbate, the two most abundant endogenous antioxidants, were investigated by pulse radiolysis. Rate constants in the order of 10 M s were found. Alkyl radicals react at almost diffusion controlled rates and irreversibly with oxygen to form peroxyl radicals, and competition with this reaction is the benchmark for efficient repair in vivo. We consider repair of protein radicals and assume comparable rate constants for the reactions of GSH/ascorbate with peptide alkyl radicals and with alkyl radicals on a protein surface. Given physiological concentrations of oxygen, GSH and ascorbate, protein peroxyl radicals will always be a major product of protein alkyl radicals in vivo. Therefore, if they are formed by oxidative stress, protein alkyl radicals are a probable cause for biological damage.
[Mh] Termos MeSH primário: Alanina/análogos & derivados
Antioxidantes/química
Ácido Ascórbico/química
Glutationa/química
Fenilalanina/análogos & derivados
Piperazinas/química
[Mh] Termos MeSH secundário: Cinética
Oxirredução
Estresse Oxidativo
Oxigênio/química
Peróxidos/química
Radiólise de Impulso
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Antioxidants); 0 (Peroxides); 0 (Piperazines); 3170-83-0 (perhydroxyl radical); 47E5O17Y3R (Phenylalanine); GAN16C9B8O (Glutathione); OF5P57N2ZX (Alanine); PQ6CK8PD0R (Ascorbic Acid); S88TT14065 (Oxygen)
[Em] Mês de entrada:1710
[Cu] Atualização por classe:171031
[Lr] Data última revisão:
171031
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170924
[St] Status:MEDLINE


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[PMID]:28418706
[Au] Autor:Georgiou CD; Zisimopoulos D; Kalaitzopoulou E; Quinn RC
[Ad] Endereço:1 Department of Biology, University of Patras , Patras, Greece .
[Ti] Título:Radiation-Driven Formation of Reactive Oxygen Species in Oxychlorine-Containing Mars Surface Analogues.
[So] Source:Astrobiology;17(4):319-336, 2017 Apr.
[Is] ISSN:1557-8070
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The present study demonstrates that γ-radiolyzed perchlorate-containing Mars soil salt analogues (in a CO atmosphere) generate upon H O wetting the reactive oxygen species (ROS) superoxide radical (O ), hydrogen peroxide (H O ), and hydroxyl radicals ( OH). This study also validates that analogue radiolysis forms oxychlorine species that, in turn, can UV-photolyze to OH upon UV photolysis. This investigation was made possible by the development of a new assay for inorganic-origin O and H O determination and by the modification of a previous assay for soil OH. Results show that radiolyzed Mg(ClO ) generates H O and OH; and when included as part of a mixture analogous to the salt composition of samples analyzed at the Mars Phoenix site, the analogue generated O , H O , and OH, with OH levels 150-fold higher than in the radiolyzed Mg(ClO ) samples. Radiolyzed Mars Phoenix site salt analogue that did not contain Mg(ClO ) generated only OH also at 150-fold higher concentration than Mg(ClO ) alone. Additionally, UV photolysis of the perchlorate γ radiolysis product chlorite (ClO ) generated the oxychlorine products trihalide (Cl ), chlorine dioxide (ClO ), and hypochlorite (ClO ), with the formation of OH by UV photolysis of ClO . While the generation of ROS may have contributed in part to CO production in the Viking Labeled Release (LR) experiment and O (g) release in the Viking Gas Exchange (GEx) experiment, our results indicate that they are not likely to be the major contributor to the LR and GEx results. However, due to their highly reactive nature, they are expected to play a significant role in the alteration of organics on Mars. Additionally, experiments with hypochlorite show that the thermal stability of NaClO is in the range of the thermal stability observed for thermally liable oxidant responsible for the Viking LR results. Key Words: Mars-Oxygen-Salts-Radiation-Habitability. Astrobiology 17, 319-336.
[Mh] Termos MeSH primário: Cloro/química
Radiação Cósmica
Meio Ambiente Extraterreno
Marte
Espécies Reativas de Oxigênio/química
[Mh] Termos MeSH secundário: Cloratos/química
Peróxido de Hidrogênio/química
Radical Hidroxila/química
Compostos de Magnésio/química
Fotólise
Radiólise de Impulso
Superóxidos/química
Raios Ultravioleta
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Chlorates); 0 (Magnesium Compounds); 0 (Reactive Oxygen Species); 11062-77-4 (Superoxides); 3352-57-6 (Hydroxyl Radical); 4R7X1O2820 (Chlorine); BBX060AN9V (Hydrogen Peroxide); M536P01U3N (magnesium chlorate)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:170508
[Lr] Data última revisão:
170508
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170419
[St] Status:MEDLINE
[do] DOI:10.1089/ast.2016.1539


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[PMID]:28118761
[Au] Autor:Szabó L; Mile V; Tóth T; Balogh GT; Földes T; Takács E; Wojnárovits L
[Ad] Endereço:a Centre for Energy Research, Hungarian Academy of Sciences , Institute for Energy Security and Environmental Safety , Budapest , Hungary.
[Ti] Título:On the complex OH/ O -induced free radical chemistry of arylalkylamines with special emphasis on the contribution of the alkylamine side chain.
[So] Source:Free Radic Res;51(2):124-140, 2017 Feb.
[Is] ISSN:1029-2470
[Cp] País de publicação:England
[La] Idioma:eng
[Ab] Resumo:A full account of the OH-induced free radical chemistry of an arylalkylamine is given taking all the possible reaction pathways quantitatively into consideration. Such knowledge is indispensable when the alkylamine side chain plays a crucial role in biological activity. The fundamental reactions are investigated on the model compound N-methyl-3-phenypropylamine (MPPA), and extended to its biologically active analog, to the antidepressant fluoxetine (FLX). Pulse radiolysis techniques were applied including redox titration and transient spectral analysis supplemented with DFT calculations. The contribution of the amine moiety to the free radical-induced oxidation mechanism appeared to be appreciable. O was used to observe hydrogen atom abstraction events at pH 14 giving rise to the strongly reducing α-aminoalkyl radicals (∼38% of the radical yield) and to benzyl (∼4%), ß-aminoalkyl (∼24%), and aminyl radicals (∼31%) of MPPA. One-electron transfer was also observed yielding aminium radicals with low efficiency (∼3%). In the OH-induced oxidation protonated α-aminoalkyl (∼49%), ß-aminoalkyl (∼27%), benzyl radicals (∼4%), and aminium radicals (∼5%) are initially generated on the side chain of MPPA at pH 6, whereas hydroxycyclohexadienyl radicals (∼15%) were also produced. These initial events are followed by complex protonation-deprotonation reactions establishing acid-base equilibria; however, these processes are limited by the transient nature of the radicals and the kinetics of the ongoing reactions. The contribution of the radicals from the side chain alkylamine substituent of FLX totals up to ∼54% of the initially available oxidant yield.
[Mh] Termos MeSH primário: Aminas/química
Radicais Livres/química
Radical Hidroxila/química
Água/química
[Mh] Termos MeSH secundário: Transporte de Elétrons
Concentração de Íons de Hidrogênio
Cinética
Oxirredução
Radiólise de Impulso
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Amines); 0 (Free Radicals); 059QF0KO0R (Water); 3352-57-6 (Hydroxyl Radical)
[Em] Mês de entrada:1703
[Cu] Atualização por classe:170330
[Lr] Data última revisão:
170330
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:170126
[St] Status:MEDLINE
[do] DOI:10.1080/10715762.2017.1287356


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[PMID]:27992185
[Au] Autor:Fujikawa M; Kobayashi K; Tsutsui Y; Tanaka T; Kozawa T
[Ad] Endereço:The Institute of Scientific and Industrial Research, Osaka University , Mihogaoka 8-1, Osaka, Ibaraki 567-0047, Japan.
[Ti] Título:Rational Tuning of Superoxide Sensitivity in SoxR, the [2Fe-2S] Transcription Factor: Implications of Species-Specific Lysine Residues.
[So] Source:Biochemistry;56(2):403-410, 2017 Jan 17.
[Is] ISSN:1520-4995
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:In Escherichia coli, the [2Fe-2S] transcriptional factor, SoxR, functions as a sensor of oxidative stress. The transcriptional activity in SoxR is regulated by the reversible oxidation and reduction of [2Fe-2S] clusters. We previously proposed that superoxide (O ) has a direct role as a signal for E. coli SoxR and that the sensitivity of the E. coli SoxR response to O is 10-fold higher than that of Pseudomonas aeruginosa SoxR. The difference between the two homologues reflects interspecies differences in the regulatory role of O activation. To investigate the determinants of SoxR's sensitivity to O , we substituted several amino acids that are not conserved among enteric bacteria SoxR homologues and investigated the interaction of SoxR with O using pulse radiolysis. The substitution of E. coli SoxR Lys residues 89 and 92 with Ala residues (K89AK92A), located close to [2Fe-2S] clusters, dramatically affected this protein's reaction with O . The second-order rate constant of the reaction was 3.3 × 10 M s , which was 10 times smaller than that of wild-type SoxR. Conversely, the corresponding substitution of Ala90 with Lys in P. aeruginosa SoxR increased the rate approximately 10-fold. In contrast, introductions of the Arg127Ser128Asp129 → Leu127Gln128Ala129 substitution into E. coli SoxR, and the corresponding substitution (Leu125Gln126Ala127 → Arg125Ser126Asp127) in P. aeruginosa SoxR, did not affect the reaction rates. In addition, the Lys mutation in E. coli SoxR (K89AK92A) showed a defect in vivo transcriptional activity by measuring ß-galactosidase expression in response to paraquat. Our findings clearly support the idea Lys is critical to the response to O and further transcriptional activity of SoxR.
[Mh] Termos MeSH primário: Proteínas de Bactérias/química
Escherichia coli/genética
Lisina/química
Pseudomonas aeruginosa/genética
Superóxidos/química
Fatores de Transcrição/química
[Mh] Termos MeSH secundário: Alanina/química
Alanina/metabolismo
Sequência de Aminoácidos
Substituição de Aminoácidos
Proteínas de Bactérias/genética
Proteínas de Bactérias/metabolismo
Escherichia coli/efeitos dos fármacos
Escherichia coli/metabolismo
Escherichia coli/efeitos da radiação
Cinética
Lisina/metabolismo
Modelos Moleculares
Mutação
Oxidantes/farmacologia
Estresse Oxidativo
Paraquat/farmacologia
Domínios Proteicos
Estrutura Secundária de Proteína
Pseudomonas aeruginosa/efeitos dos fármacos
Pseudomonas aeruginosa/metabolismo
Pseudomonas aeruginosa/efeitos da radiação
Radiólise de Impulso
Proteínas Recombinantes/química
Proteínas Recombinantes/genética
Proteínas Recombinantes/metabolismo
Alinhamento de Sequência
Especificidade da Espécie
Relação Estrutura-Atividade
Superóxidos/metabolismo
Fatores de Transcrição/genética
Fatores de Transcrição/metabolismo
Ativação Transcricional
beta-Galactosidase/genética
beta-Galactosidase/metabolismo
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Bacterial Proteins); 0 (Oxidants); 0 (Recombinant Proteins); 0 (Transcription Factors); 11062-77-4 (Superoxides); 137804-81-0 (SoxR protein, Bacteria); EC 3.2.1.23 (beta-Galactosidase); K3Z4F929H6 (Lysine); OF5P57N2ZX (Alanine); PLG39H7695 (Paraquat)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:170515
[Lr] Data última revisão:
170515
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:161220
[St] Status:MEDLINE
[do] DOI:10.1021/acs.biochem.6b01096


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[PMID]:27869553
[Au] Autor:Yamashita S; Ma J; Marignier JL; Hiroki A; Taguchi M; Mostafavi M; Katsumura Y
[Ad] Endereço:a Nuclear Professional School, School of Engineering, The University of Tokyo, Shirakata-shirane 2-22, Tokai-mura, Naka-gun, Ibaraki, 319-1188 Japan.
[Ti] Título:Radiation-Induced Chemical Reactions in Hydrogel of Hydroxypropyl Cellulose (HPC): A Pulse Radiolysis Study.
[So] Source:Radiat Res;186(6):650-658, 2016 Dec.
[Is] ISSN:1938-5404
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:We performed studies on pulse radiolysis of highly transparent and shape-stable hydrogels of hydroxypropyl cellulose (HPC) that were prepared using a radiation-crosslinking technique. Several fundamental aspects of radiation-induced chemical reactions in the hydrogels were investigated. With radiation doses less than 1 kGy, degradation of the HPC matrix was not observed. The rate constants of the HPC composing the matrix, with two water decomposition radicals [hydroxyl radical ( OH) and hydrated electron ([Formula: see text])] in the gels, were determined to be 4.5 × 10 and 1.8 × 10 M s , respectively. Direct ionization of HPC in the matrix slightly increased the initial yield of [Formula: see text], but the additionally produced amount of [Formula: see text] disappeared immediately within 200 ps, indicating fast recombination of [Formula: see text] with hole radicals on HPC or on surrounding hydration water molecules. Reactions of [Formula: see text] with nitrous oxide (N O) and nitromethane (CH NO ) were also examined. Decay of [Formula: see text] due to scavenging by N O and CH NO were both slower in hydrogels than in aqueous solutions, showing slower diffusions of the reactants in the gel matrix. The degree of decrease in the decay rate was more effective for N O than for CH NO , revealing lower solubility of N O in gel than in water. It is known that in viscous solvents, such as ethylene glycol, CH NO exhibits a transient effect, which is a fast reaction over the contact distance of reactants and occurs without diffusions of reactants. However, such an effect was not observed in the hydrogel used in the current study. In addition, the initial yield of [Formula: see text], which is affected by the amount of the scavenged precursor of [Formula: see text], in hydrogel containing N O was slightly higher than that in water containing N O, and the same tendency was found for CH NO .
[Mh] Termos MeSH primário: Celulose/análogos & derivados
Hidrogéis/química
[Mh] Termos MeSH secundário: Celulose/química
Cinética
Radiólise de Impulso
Água/química
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Hydrogels); 059QF0KO0R (Water); 9004-34-6 (Cellulose); RFW2ET671P (hydroxypropylcellulose)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:170522
[Lr] Data última revisão:
170522
[Sb] Subgrupo de revista:IM; S
[Da] Data de entrada para processamento:161122
[St] Status:MEDLINE
[do] DOI:10.1667/RR14539.1


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[PMID]:27379473
[Au] Autor:Kobayashi K; Nakagaki M; Ishikawa H; Iwai K; O'Brian MR; Ishimori K
[Ad] Endereço:The Institute of Scientific and Industrial Research, Osaka University , Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan.
[Ti] Título:Redox-Dependent Dynamics in Heme-Bound Bacterial Iron Response Regulator (Irr) Protein.
[So] Source:Biochemistry;55(29):4047-54, 2016 Jul 26.
[Is] ISSN:1520-4995
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The iron response regulator (Irr) protein from Bradyrhizobium japonicum mediates iron-dependent regulation of heme biosynthesis. Irr degrades in response to heme availability through a process that involves the binding of heme to Cys-29 in the heme regulatory motif (HRM) in the presence of molecular oxygen. In this work, we assessed the dynamics of one-electron reduction of heme-bound Irr by monitoring the formation of transient intermediates by pulse radiolysis. Hydrated electrons generated by pulse radiolysis reduced heme iron-bound Irr, facilitating the binding of molecular oxygen to the heme iron in Irr through an initial intermediate with an absorption maximum at 420 nm. This initial intermediate was converted to a secondary intermediate with an absorption maximum at 425 nm, with a first-order rate constant of 1.0 × 10(4) s(-1). The Cys-29 → Ala (C29A) mutant of Irr, on the other hand, did not undergo the secondary phase, implying that ligand exchange of Cys-29 for another ligand takes place during the process. Spectral changes during the reduction of the heme-bound Irr revealed that binding of CO to ferrous heme consisted of two phases with kon values of 1.3 × 10(5) and 2.5 × 10(4) M(-1) s(-1), a finding consistent with the presence of two distinct hemes in Irr. In aerobic solutions, by contrast, oxidation of the ferrous heme to the ferric form was found to be a two-phase process. The C29A mutant was similarly oxidized, but this occurred as a single-phase process. We speculate that a reactive oxygen species essential for degradation of the protein is generated during the oxidation process.
[Mh] Termos MeSH primário: Proteínas de Bactérias/química
Proteínas de Bactérias/metabolismo
Heme/química
Ferro/química
Fatores de Transcrição/química
Fatores de Transcrição/metabolismo
[Mh] Termos MeSH secundário: Substituição de Aminoácidos
Proteínas de Bactérias/genética
Sítios de Ligação
Cinética
Ligantes
Mutagênese Sítio-Dirigida
Oxirredução
Oxigênio/metabolismo
Radiólise de Impulso
Proteínas Recombinantes/química
Proteínas Recombinantes/genética
Proteínas Recombinantes/metabolismo
Fatores de Transcrição/genética
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Bacterial Proteins); 0 (Ligands); 0 (Recombinant Proteins); 0 (Transcription Factors); 0 (iron response regulator protein, Bacteria); 42VZT0U6YR (Heme); E1UOL152H7 (Iron); S88TT14065 (Oxygen)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:170509
[Lr] Data última revisão:
170509
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160706
[St] Status:MEDLINE
[do] DOI:10.1021/acs.biochem.6b00512


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[PMID]:27203407
[Au] Autor:Mummadisetti MP; Frankel LK; Bellamy HD; Sallans L; Goettert JS; Brylinski M; Bricker TM
[Ad] Endereço:Division of Biochemistry and Molecular Biology, Department of Biological Sciences, Louisiana State University , Baton Rouge, Louisiana 70803, United States.
[Ti] Título:Use of Protein Cross-Linking and Radiolytic Labeling To Elucidate the Structure of PsbO within Higher-Plant Photosystem II.
[So] Source:Biochemistry;55(23):3204-13, 2016 Jun 14.
[Is] ISSN:1520-4995
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:We have used protein cross-linking with the zero-length cross-linker 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, and radiolytic footprinting coupled with high-resolution tandem mass spectrometry, to examine the structure of higher-plant PsbO when it is bound to Photosystem II. Twenty intramolecular cross-linked residue pairs were identified. On the basis of this cross-linking data, spinach PsbO was modeled using the Thermosynechococcus vulcanus PsbO structure as a template, with the cross-linking distance constraints incorporated using the MODELLER program. Our model of higher-plant PsbO identifies several differences between the spinach and cyanobacterial proteins. The N-terminal region is particularly interesting, as this region has been suggested to be important for oxygen evolution and for the specific binding of PsbO to Photosystem II. Additionally, using radiolytic mapping, we have identified regions on spinach PsbO that are shielded from the bulk solvent. These domains may represent regions on PsbO that interact with other components, as yet unidentified, of the photosystem.
[Mh] Termos MeSH primário: Reagentes para Ligações Cruzadas
Cianobactérias/metabolismo
Complexo de Proteína do Fotossistema II/química
Proteínas de Plantas/química
Radiólise de Impulso
Spinacia oleracea/metabolismo
[Mh] Termos MeSH secundário: Sequência de Aminoácidos
Cristalografia por Raios X
Cianobactérias/crescimento & desenvolvimento
Espectrometria de Massas
Modelos Moleculares
Complexo de Proteína do Fotossistema II/metabolismo
Proteínas de Plantas/metabolismo
Ligação Proteica
Conformação Proteica
Pegadas de Proteínas
Homologia de Sequência de Aminoácidos
Spinacia oleracea/crescimento & desenvolvimento
Síncrotrons
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Cross-Linking Reagents); 0 (Photosystem II Protein Complex); 0 (Plant Proteins); 0 (oxygen-evolving enhancer protein 1, plant)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:170502
[Lr] Data última revisão:
170502
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160521
[St] Status:MEDLINE
[do] DOI:10.1021/acs.biochem.6b00365


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[PMID]:27126506
[Au] Autor:Wherland S; Miyazaki K; Pecht I
[Ad] Endereço:Department of Chemistry, Washington State University , Pullman, Washington 99164-4630, United States.
[Ti] Título:Intramolecular Electron Transfer in the Bacterial Two-Domain Multicopper Oxidase mgLAC.
[So] Source:Biochemistry;55(21):2960-6, 2016 May 31.
[Is] ISSN:1520-4995
[Cp] País de publicação:United States
[La] Idioma:eng
[Ab] Resumo:The kinetics of the intramolecular electron transfer process in mgLAC, a bacterial two-domain multicopper oxidase (MCO), were investigated by pulse radiolysis. The reaction is initiated by CO2(-) radicals produced in anaerobic, aqueous solutions of the enzyme by microsecond pulses of radiation. A sequence of pulses of CO2(-) radicals enables examination of the reductive half-cycle of the MCO catalysis. This is done by titrations of the Type 1 (T1) Cu(II) site and monitoring of the time course and amplitude of its reoxidation by internal electron transfer (ET) to the Type 3 site. Comparison of the internal ET kinetics observed for mgLAC with those of other MCOs studied by pulse radiolysis shows that they exhibit distinct reactivities. One main cause for the different reactivities is the broad range of T1 copper redox potentials, from the moderate potential of bacterial enzymes to the high potential of fungal laccases, and this possibly also reflects evolutionary quaternary structural adaptation of the MCO family to the wide range of reducing substrates that they oxidize while maintaining efficient reduction of the common substrate, molecular oxygen.
[Mh] Termos MeSH primário: Proteínas de Bactérias/química
Cobre/química
Elétrons
Lacase/química
Oxirredutases/química
[Mh] Termos MeSH secundário: Transporte de Elétrons
Cinética
Modelos Moleculares
Oxirredução
Radiólise de Impulso
Termodinâmica
[Pt] Tipo de publicação:JOURNAL ARTICLE
[Nm] Nome de substância:
0 (Bacterial Proteins); 789U1901C5 (Copper); EC 1.- (Oxidoreductases); EC 1.10.3.2 (Laccase)
[Em] Mês de entrada:1705
[Cu] Atualização por classe:170509
[Lr] Data última revisão:
170509
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160430
[St] Status:MEDLINE
[do] DOI:10.1021/acs.biochem.6b00158


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[PMID]:26931377
[Au] Autor:Sevilla MD; Kumar A; Adhikary A
[Ad] Endereço:Department of Chemistry, Oakland University , Rochester, Michigan 48309, United States.
[Ti] Título:Comment on "Proton Transfer of Guanine Radical Cations Studied by Time-Resolved Resonance Raman Spectroscopy Combined with Pulse Radiolysis".
[So] Source:J Phys Chem B;120(11):2984-6; discussion 2987-9, 2016 Mar 24.
[Is] ISSN:1520-5207
[Cp] País de publicação:United States
[La] Idioma:eng
[Mh] Termos MeSH primário: Prótons
Radiólise de Impulso
[Mh] Termos MeSH secundário: Cátions/química
Radicais Livres/química
Guanina/química
Análise Espectral Raman
[Pt] Tipo de publicação:COMMENT; JOURNAL ARTICLE; RESEARCH SUPPORT, N.I.H., EXTRAMURAL
[Nm] Nome de substância:
0 (Cations); 0 (Free Radicals); 0 (Protons); 5Z93L87A1R (Guanine)
[Em] Mês de entrada:1608
[Cu] Atualização por classe:170324
[Lr] Data última revisão:
170324
[Sb] Subgrupo de revista:IM
[Da] Data de entrada para processamento:160303
[St] Status:MEDLINE
[do] DOI:10.1021/acs.jpcb.5b12607



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