The Peroxidatic Thiol of Peroxiredoxin 1 is Nitrosated by Nitrosoglutathione but Coordinates to the Dinitrosyl Iron Complex of Glutathione.

Protein S-nitrosation is an important consequence of NO●·metabolism with implications in physiology and pathology. The mechanisms responsible for S-nitrosation in vivo remain debatable and kinetic data on protein S-nitrosation by different agents are limited. 2-Cys peroxiredoxins, in particular Prx1 and Prx2, were detected as being S-nitrosated in multiple mammalian cells under a variety of conditions.

The bicarbonate/carbon dioxide pair increases hydrogen peroxide-mediated hyperoxidation of human peroxiredoxin 1.

2-Cys peroxiredoxins (Prxs) rapidly reduce HO, thereby acting as antioxidants and also as sensors and transmitters of HO signals in cells. Interestingly, eukaryotic 2-Cys Prxs lose their peroxidase activity at high HO levels. Under these conditions, HO oxidizes the sulfenic acid derivative of the Prx peroxidatic Cys (CSOH) to the sulfinate (CSO) and sulfonated (CSO) forms, redirecting the CSOH intermediate from the catalytic cycle to the hyperoxidation/inactivation pathway.

Urate hydroperoxide oxidizes human peroxiredoxin 1 and peroxiredoxin 2.

Urate hydroperoxide is a product of the oxidation of uric acid by inflammatory heme peroxidases. The formation of urate hydroperoxide might be a key event in vascular inflammation, where there is large amount of uric acid and inflammatory peroxidases. Urate hydroperoxide oxidizes glutathione and sulfur-containing amino acids and is expected to react fast toward reactive thiols from peroxiredoxins (Prxs).

A 14.7 kDa protein from Francisella tularensis subsp. novicida (named FTN_1133), involved in the response to oxidative stress induced by organic peroxides, is not endowed with thiol-dependent peroxidase activity.

Francisella genus comprises Gram-negative facultative intracellular bacteria that are among the most infectious human pathogens. A protein of 14.7 KDa named as FTN_1133 was previously described as a novel hydroperoxide resistance protein in F.

Insights into the specificity of thioredoxin reductase-thioredoxin interactions. A structural and functional investigation of the yeast thioredoxin system.

The enzymatic activity of thioredoxin reductase enzymes is endowed by at least two redox centers: a flavin and a dithiol/disulfide CXXC motif. The interaction between thioredoxin reductase and thioredoxin is generally species-specific, but the molecular aspects related to this phenomenon remain elusive. Here, we investigated the yeast cytosolic thioredoxin system, which is composed of NADPH, thioredoxin reductase (ScTrxR1), and thioredoxin 1 (ScTrx1) or thioredoxin 2 (ScTrx2).

Crystallization and preliminary X-ray analysis of a decameric form of cytosolic thioredoxin peroxidase 1 (Tsa1), C47S mutant, from Saccharomyces cerevisiae.

Saccharomyces cerevisiae cytosolic thioredoxin peroxidase 1 (cTPxI or Tsa1) is a bifunctional enzyme with protective roles in cellular defence against oxidative and thermal stress that exhibits both peroxidase and chaperone activities. Protein overoxidation and/or high temperatures induce great changes in its quaternary structure and lead to its assembly into large complexes that possess chaperone activity. A recombinant mutant of Tsa1 from S.

Reactive cysteine in proteins: protein folding, antioxidant defense, redox signaling and more.

Cysteine plays structural roles in proteins and can also participate in electron transfer reactions, when some structural folds provide appropriated environments for stabilization of its sulfhydryl group in the anionic form, called thiolate (RS(-)). In contrast, sulfhydryl group of free cysteine has a relatively high pK(a) (8,5) and as a consequence is relatively inert for redox reaction in physiological conditions. Thiolate is considerable more powerful as nucleophilic agent than its protonated form, therefore, reactive cysteine are present mainly in its anionic form in proteins.

Crystallization and preliminary X-ray diffraction analysis of NADPH-dependent thioredoxin reductase I from Saccharomyces cerevisiae.

Thioredoxin reductase 1 (Trr1) from Saccharomyces cerevisiae is a member of the family of pyridine nucleotide-disulfide oxidoreductases capable of reducing the redox-active disulfide bond of the cytosolic thioredoxin 1 (Trx1) and thioredoxin 2 (Trx2). NADPH, Trr1 and Trx1 (or Trx2) comprise the thioredoxin system, which is involved in several biological processes, including the reduction of disulfide bonds and response to oxidative stress. Recombinant Trr1 was expressed in Escherichia coli as a His6-tagged fusion protein and purified by nickel-affinity chromatography.

Crystallization and preliminary X-ray diffraction analysis of an oxidized state of Ohr from Xylella fastidiosa.

Xylella fastidiosa organic hydroperoxide-resistance protein (Ohr) is a dithiol-dependent peroxidase that is widely conserved in several pathogenic bacteria with high affinity for organic hydroperoxides. The protein was crystallized using the hanging-drop vapour-diffusion method in the presence of PEG 4000 as precipitant after treatment with organic peroxide (t-butyl hydroperoxide). X-ray diffraction data were collected to a maximum resolution of 1.

Organic hydroperoxide resistance gene encodes a thiol-dependent peroxidase.

ohr (organic hydroperoxide resistance gene) is present in several species of bacteria, and its deletion renders cells specifically sensitive to organic peroxides. The goal of this work was to determine the biochemical function of Ohr from Xylella fastidiosa. All of the Ohr homologues possess two cysteine residues, one of them located in a VCP motif, which is also present in all of the proteins from the peroxiredoxin family.