The Experts below are selected from a list of 6 Experts worldwide ranked by ideXlab platform
Nelson Ramos Stradiotto - One of the best experts on this subject based on the ideXlab platform.
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electrochemical evidence of Sulfinic Acid Derivative as an intermediate in the reduction of aromatic sulfonyl chloride in an aprotic medium
Eclética Química, 2005Co-Authors: A C D Angelo, Sonia M A Jorge, Nelson Ramos StradiottoAbstract:The electrochemical reduction of p-nitrobenzenesulfonyl chloride (NBSCl) in dimethylsulfoxide (DMSO) solution is used here as a model to investigate the role of Sulfinic Acid Derivative in this compound's global reduction process. Cyclic voltammetric experiments reveal the production of Sulfinic Acid Derivative, which is important in chemical reactions involving the original compound and other intermediates. This paper also discusses the probable mechanisms of the reduction.
A C D Angelo - One of the best experts on this subject based on the ideXlab platform.
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electrochemical evidence of Sulfinic Acid Derivative as an intermediate in the reduction of aromatic sulfonyl chloride in an aprotic medium
Eclética Química, 2005Co-Authors: A C D Angelo, Sonia M A Jorge, Nelson Ramos StradiottoAbstract:The electrochemical reduction of p-nitrobenzenesulfonyl chloride (NBSCl) in dimethylsulfoxide (DMSO) solution is used here as a model to investigate the role of Sulfinic Acid Derivative in this compound's global reduction process. Cyclic voltammetric experiments reveal the production of Sulfinic Acid Derivative, which is important in chemical reactions involving the original compound and other intermediates. This paper also discusses the probable mechanisms of the reduction.
Sonia M A Jorge - One of the best experts on this subject based on the ideXlab platform.
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electrochemical evidence of Sulfinic Acid Derivative as an intermediate in the reduction of aromatic sulfonyl chloride in an aprotic medium
Eclética Química, 2005Co-Authors: A C D Angelo, Sonia M A Jorge, Nelson Ramos StradiottoAbstract:The electrochemical reduction of p-nitrobenzenesulfonyl chloride (NBSCl) in dimethylsulfoxide (DMSO) solution is used here as a model to investigate the role of Sulfinic Acid Derivative in this compound's global reduction process. Cyclic voltammetric experiments reveal the production of Sulfinic Acid Derivative, which is important in chemical reactions involving the original compound and other intermediates. This paper also discusses the probable mechanisms of the reduction.
Ursini Fulvio - One of the best experts on this subject based on the ideXlab platform.
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The mycobacterial thioredoxin peroxidase can act as a one-cysteine peroxiredoxin
2006Co-Authors: M. Trujillo, P. Mauri, L. Benazzi, M. Comini, A. De Palma, L. Flohe, R. Radi, M. Stehr, M. Singh, Ursini FulvioAbstract:Abstract Thioredoxin peroxidase (TPx) has been reported to dominate the defense against H(2)O(2), other hydroperoxides, and peroxynitrite at the expense of thioredoxin (Trx) B and C in Mycobacterium tuberculosis (Mt). By homology, the enzyme has been classified as an atypical 2-C-peroxiredoxin (Prx), with Cys(60) as the "peroxidatic" cysteine (C(P)) forming a complex catalytic center with Cys(93) as the "resolving" cysteine (C(R)). Site-directed mutagenesis confirms Cys(60) to be C(P) and Cys(80) to be catalytically irrelevant. Replacing Cys(93) with serine leads to fast inactivation as seen by conventional activity determination, which is associated with oxidation of Cys(60) to a Sulfinic Acid Derivative. However, in comparative stopped-flow analysis, WT-MtTPx and MtTPx C93S reduce peroxynitrite and react with TrxB and -C similarly fast. Reduction of pre-oxidized WT-MtTPx and MtTPx C93S by MtTrxB is demonstrated by monitoring the redox-dependent tryptophan fluorescence of MtTrxB. Furthermore, MtTPx C93S remains stable for 10 min at a morpholinosydnonimine hydrochloride-generated low flux of peroxynitrite and excess MtTrxB in a dihydrorhodamine oxidation model. Liquid chromatography-tandem mass spectrometry analysis revealed disulfide bridges between Cys(60) and Cys(93) and between Cys(60) and Cys(80) in oxidized WT-MtTPx. Reaction of pre-oxidized WT-MtTPx and MtTPx C93S with MtTrxB C34S or MtTrxC C40S yielded dead-end intermediates in which the Trx mutants are preferentially linked via disulfide bonds to Cys(60) and never to Cys(93) of the TPx. It is concluded that neither Cys(80) nor Cys(93) is required for the catalytic cycle of the peroxidase. Instead, MtTPx can react as a 1-C-Prx with Cys(60) being the site of attack for both the oxidizing and the reducing substrate. The role of Cys(93) is likely to conserve the oxidation equivalents of the sulfenic Acid state of C(P) as a disulfide bond to prevent overoxidation of Cys(60) under a restricted supply of reducing substrate
M. Trujillo - One of the best experts on this subject based on the ideXlab platform.
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The mycobacterial thioredoxin peroxidase can act as a one-cysteine peroxiredoxin
2006Co-Authors: M. Trujillo, P. Mauri, L. Benazzi, M. Comini, A. De Palma, L. Flohe, R. Radi, M. Stehr, M. Singh, Ursini FulvioAbstract:Abstract Thioredoxin peroxidase (TPx) has been reported to dominate the defense against H(2)O(2), other hydroperoxides, and peroxynitrite at the expense of thioredoxin (Trx) B and C in Mycobacterium tuberculosis (Mt). By homology, the enzyme has been classified as an atypical 2-C-peroxiredoxin (Prx), with Cys(60) as the "peroxidatic" cysteine (C(P)) forming a complex catalytic center with Cys(93) as the "resolving" cysteine (C(R)). Site-directed mutagenesis confirms Cys(60) to be C(P) and Cys(80) to be catalytically irrelevant. Replacing Cys(93) with serine leads to fast inactivation as seen by conventional activity determination, which is associated with oxidation of Cys(60) to a Sulfinic Acid Derivative. However, in comparative stopped-flow analysis, WT-MtTPx and MtTPx C93S reduce peroxynitrite and react with TrxB and -C similarly fast. Reduction of pre-oxidized WT-MtTPx and MtTPx C93S by MtTrxB is demonstrated by monitoring the redox-dependent tryptophan fluorescence of MtTrxB. Furthermore, MtTPx C93S remains stable for 10 min at a morpholinosydnonimine hydrochloride-generated low flux of peroxynitrite and excess MtTrxB in a dihydrorhodamine oxidation model. Liquid chromatography-tandem mass spectrometry analysis revealed disulfide bridges between Cys(60) and Cys(93) and between Cys(60) and Cys(80) in oxidized WT-MtTPx. Reaction of pre-oxidized WT-MtTPx and MtTPx C93S with MtTrxB C34S or MtTrxC C40S yielded dead-end intermediates in which the Trx mutants are preferentially linked via disulfide bonds to Cys(60) and never to Cys(93) of the TPx. It is concluded that neither Cys(80) nor Cys(93) is required for the catalytic cycle of the peroxidase. Instead, MtTPx can react as a 1-C-Prx with Cys(60) being the site of attack for both the oxidizing and the reducing substrate. The role of Cys(93) is likely to conserve the oxidation equivalents of the sulfenic Acid state of C(P) as a disulfide bond to prevent overoxidation of Cys(60) under a restricted supply of reducing substrate
