排序方式: 共有11条查询结果,搜索用时 15 毫秒
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Sebastián A. Suárez Marcelo A. MartíPablo M. De Biase Darío A. EstrinSara E. Bari Fabio Doctorovich 《Polyhedron》2007
The role of nitric oxide (NO) as a signalling molecule in biological systems has been thoroughly studied in the last decades. More recently, there has been an increasing interest in the one-electron reduction product of NO, namely nitroxyl (HNO/NO−). Some studies suggest that nitroxyl can be produced by nitric oxide synthases under certain conditions, and that distinct pharmacological effects are observed for NO and nitroxyl donors. HNO is capable of react with heme proteins, thiols, molecular oxygen, NO and HNO itself. However, only recently the different reactivity patterns are being thoroughly understood. Heme model compounds offer the opportunity to study the reaction kinetics without the complexity arising from ligand interactions with the protein matrix. In this study we analyzed the reaction between the commonly used nitroxyl donors sodium trioxodinitrate and toluene sulfohydroxamic acid, with the ferric model compounds microperoxidase-11 (MP11) and the cationic metalloporphyrin [FeIIITEPyP]5+ (Tetrakis N-ethylpyridinium-2yl porphyne). Our results show that there are two alternative modes of reactivity for nitroxyl donors towards heme in aqueous solutions. The first one comprises the heme assisted decomposition of the donor, enhancing its decomposition rate more than 100-fold. In the second, the donor produces HNO which subsequently reacts with the porphyrin. The observed rate constants (of about 105 M−1 s−1) are consistent with the estimated data for the HNO reaction with heme proteins, and may be controlled by the leaving water ligand. This rate constant probably represents an upper limit for the bimolecular rate constant of HNO towards these proteins. 相似文献
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MP-ifisanundecapeptideobtainedfrompepsindigestionofcytochromeC.Itisconsideredamodelforc-typecytochromes.MP-lIretainsaminoacidresidues11-21ofcytochromeC.Amongtheresidues,Cys-14andCys-17arebondedtothehemeCvinylgroupsandHis-18servesasaproximalfifthligandtotheFeatom.ItisconsideredaperoxidasebecauseitSactivityissimilartothatofperoxidasesinseveralways.ItwasreportedthatMP-ifcanundergothequasi-reversibleelectrochemicalreactionatmetalelectrodes.Inthispaper,electrochemicalreactionsandphotoreductio… 相似文献
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A bioelectrochemical platform has been constructed for the direct electron transfer and biosensing purposes of microperoxidase‐11 (MP‐11) immobilized on the chitosan dispersed multilayer graphene nanocomposite. The immobilized MP‐11 at the modified gold electrode displays a well‐defined and quasireversible redox peaks, with a formal potential of ?0.38 V/SCE in a buffer solution (pH 7.0). MP‐11 absorbed on the electrode surface exhibits high electrocatalytic activity toward the reduction of both oxygen and hydrogen peroxide and also shows good analytical performance for the amperometric detection of H2O2 with a linear range from 2.5 to 135 μM. These results indicate the graphene modified electrode might be used as a third generation biosensor for H2O2 detection. 相似文献
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Magneto‐controlled OR, AND and INHIB logic gates were designed using cobalt ferrite magnetic nanoparticles (CoFe2O4, saturated magnetization ca. 70 emu g?1, 17±2 nm diameter) functionalized with microperoxidase‐11. Tunable magnetic field generated by three external permanent magnets (NdFeB) upon moving them below the electrochemical cell resulted in translocation of the biofunctionalized magnetic nanoparticles between conductive and nonconductive domains of a solid plate. This resulted in electrochemically readable output signals with the Boolean logic controlled by the magnetic input signals. The current corresponding to the reversible redox process of the heme measured at ?0.4 V (vs. SCE) was considered as “1” output signal, while a small background current obtained from the conducting interface in the absence of the magnetic nanoparticles was considered as “0” output signal. Addition of H2O2 to the solution resulted in the generation of a cathodic catalytic current when the microperoxidase‐11‐functionalized magnetic nanoparticles are associated with the conductive domain of the support. This resulted in the amplification of “1” output signal and the increased difference between “1” and “0” signals generated by the cell, thus reducing the possibility of errors in the Boolean logic operations. 相似文献
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Aysu Yarman Thomas Nagel Nenad Gajovic‐Eichelmann Anna Fischer Ulla Wollenberger Frieder W. Scheller 《Electroanalysis》2011,23(3):611-618
We report on the redox behaviour of the microperoxidase‐11 (MP‐11) which has been electrostatically immobilized in a matrix of chitosan‐embedded gold nanoparticles on the surface of a glassy carbon electrode. MP‐11 contains a covalently bound heme c as the redox active group that exchanges electrons with the electrode via the gold nanoparticles. Electroactive surface concentration of MP‐11 at high scan rate is between 350±50 pmol cm?2, which reflects a multilayer process. The formal potential (E°′) of MP‐11 in the gold nanoparticles‐chitosan film was estimated to be ?(267.7±2.9) mV at pH 7.0. The heterogeneous electron transfer rate constant (ks) starts at 1.21 s?1 and levels off at 6.45 s?1 in the scan rate range from 0.1 to 2.0 V s?1. Oxidation and reduction of MP‐11 by hydrogen peroxide and superoxide, respectively have been coupled to the direct electron transfer of MP‐11. 相似文献
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Direct electrochemistry of cholesterol oxidase (ChOx) immobilized on the conductive poly‐3′,4′‐diamine‐2,2′,5′,2″‐terthiophene (PDATT) was achieved and used to create a cholesterol biosensor. A well‐defined redox peak was observed, corresponding to the direct electron transfer of the FAD/FADH2 of ChOx, and the rate constant (ks) was determined to be 0.75 s?1. Glutathione (GSH) covalently bonded with PDATT was used as a matrix for conjugating AuNPs, ChOx, and MP, simultaneously. MP co‐immobilized with ChOx on the AuNPs‐GSH/PDATT exhibited an excellent amperometric response to cholesterol. The dynamic range was from 10 to 130 μM with a detection limit of 0.3±0.04 μM. 相似文献
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Microperoxidase-11(MP-11) was immobilized on the surface of a silanized glass carbon electrode by means of the covalent bond with glutaraldehyde.The measurements of cyclic voltammetry demonstrated that the formal redox potential of immobilized MP-11 was -170mV.which is significantly more positive than that of MP-11 in a solution or immobilized on the surface of electrodes prepared with other methods.This MP-11 modified electrode showed a good electrocatalytic activity and stability for the reduction of oxygen and hydrogen peroxide. 相似文献