Some members of the glutathione peroxidase (GPx) family have been reported to accept thioredoxin as reducing substrate. However, the selenocysteine-containing ones oxidise thioredoxin (Trx), if at all, at extremely slow rates. In contrast, the Cys homolog of Drosophila melanogaster exhibits a clear preference for Trx, the net forward rate constant, k'(+2), for reduction by Trx being 1.5x10(6) M(-1) s(-1), but only 5.4 M(-1) s(-1) for glutathione. Like other CysGPxs with thioredoxin peroxidase activity, Drosophila melanogaster (Dm)GPx oxidized by H(2)O(2) contained an intra-molecular disulfide bridge between the active-site cysteine (C45; C(P)) and C91. Site-directed mutagenesis of C91 in DmGPx abrogated Trx peroxidase activity, but increased the rate constant for glutathione by two orders of magnitude. In contrast, a replacement of C74 by Ser or Ala only marginally affected activity and specificity of DmGPx. Furthermore, LC-MS/MS analysis of oxidized DmGPx exposed to a reduced Trx C35S
%0 Journal Article
%1 Maiorino.20070126
%A ?,
%D 2007/01/26/
%J J Mol Biol
%K Amino_Acid Amino_Acid_Sequence Animals Chemical Dimerization Disulfides Drosophila_melanogaster IFZ Kinetics Models Molecular Molecular_Sequence_Data Mutagenesis Peroxidases Peroxiredoxins Sequence_Homology Site-Directed Substrate_Specificity Thioredoxins glutathione_peroxidase
%N 4
%P 1033-1046
%T The thioredoxin specificity of Drosophila GPx: a paradigm for a peroxiredoxin-like mechanism of many glutathione peroxidases
%V 365
%X Some members of the glutathione peroxidase (GPx) family have been reported to accept thioredoxin as reducing substrate. However, the selenocysteine-containing ones oxidise thioredoxin (Trx), if at all, at extremely slow rates. In contrast, the Cys homolog of Drosophila melanogaster exhibits a clear preference for Trx, the net forward rate constant, k'(+2), for reduction by Trx being 1.5x10(6) M(-1) s(-1), but only 5.4 M(-1) s(-1) for glutathione. Like other CysGPxs with thioredoxin peroxidase activity, Drosophila melanogaster (Dm)GPx oxidized by H(2)O(2) contained an intra-molecular disulfide bridge between the active-site cysteine (C45; C(P)) and C91. Site-directed mutagenesis of C91 in DmGPx abrogated Trx peroxidase activity, but increased the rate constant for glutathione by two orders of magnitude. In contrast, a replacement of C74 by Ser or Ala only marginally affected activity and specificity of DmGPx. Furthermore, LC-MS/MS analysis of oxidized DmGPx exposed to a reduced Trx C35S
@article{Maiorino.20070126,
abstract = {Some members of the glutathione peroxidase (GPx) family have been reported to accept thioredoxin as reducing substrate. However, the selenocysteine-containing ones oxidise thioredoxin (Trx), if at all, at extremely slow rates. In contrast, the Cys homolog of Drosophila melanogaster exhibits a clear preference for Trx, the net forward rate constant, k'(+2), for reduction by Trx being 1.5x10(6) M(-1) s(-1), but only 5.4 M(-1) s(-1) for glutathione. Like other CysGPxs with thioredoxin peroxidase activity, Drosophila melanogaster (Dm)GPx oxidized by H(2)O(2) contained an intra-molecular disulfide bridge between the active-site cysteine (C45; C(P)) and C91. Site-directed mutagenesis of C91 in DmGPx abrogated Trx peroxidase activity, but increased the rate constant for glutathione by two orders of magnitude. In contrast, a replacement of C74 by Ser or Ala only marginally affected activity and specificity of DmGPx. Furthermore, LC-MS/MS analysis of oxidized DmGPx exposed to a reduced Trx C35S},
added-at = {2008-10-14T16:07:18.000+0200},
author = {?},
biburl = {https://www.bibsonomy.org/bibtex/2482c03361f814d195909dd986d35fd68/nutribiochem},
interhash = {4d10ba897691efb358377cddd30906b3},
intrahash = {482c03361f814d195909dd986d35fd68},
journal = {J Mol Biol},
keywords = {Amino_Acid Amino_Acid_Sequence Animals Chemical Dimerization Disulfides Drosophila_melanogaster IFZ Kinetics Models Molecular Molecular_Sequence_Data Mutagenesis Peroxidases Peroxiredoxins Sequence_Homology Site-Directed Substrate_Specificity Thioredoxins glutathione_peroxidase},
number = 4,
pages = {1033-1046},
timestamp = {2008-10-14T16:08:42.000+0200},
title = {The thioredoxin specificity of Drosophila GPx: a paradigm for a peroxiredoxin-like mechanism of many glutathione peroxidases},
volume = 365,
year = {2007/01/26/}
}