Sulfur K-edge X-ray absorption spectroscopy as an experimental probe for S-nitroso proteins

Szilágyi, Róbert K.; Schwab, David E.

doi:10.1016/j.bbrc.2005.02.127

Cited by 13 publications

(12 citation statements)

References 48 publications

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“…Therefore, and also due to the not‐less‐important property as light‐sensitive compounds, converting them into NO donor drugs5, 6 and their atmospheric implications,7 a wide range of spectroscopic and analytical methods has been applied in all of these studies 8…”

Section: Methodsmentioning

confidence: 99%

The Structure and Conformation of (CH₃)₃CSNO

Cánneva

Erben

Romano

et al. 2015

Chemistry A European J

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The gas-phase molecular structure of (CH3 )3 CSNO was investigated by using electron diffraction, allowing the first experimental geometrical parameters for an S-nitrosothiol species to be elucidated. Depending on the orientation of the -SNO group, two conformers (anti and syn) are identified in the vapor of (CH3 )3 CSNO at room temperature, the syn conformer being less abundant. The conformational landscape is further scrutinized by using vibrational spectroscopy techniques, including gas-phase and matrix-isolation IR spectroscopy, resulting in a contribution of ca. 80:20 for the anti:syn abundance ratio, in good agreement with the computed value at the MP2(full)/cc-pVTZ level of approximation. The UV/Vis and resonance Raman spectra also show the occurrence of the conformational equilibrium in the liquid phase, with a moderate post-resonance Raman signature associated with the 350 nm electronic absorption.

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Section: Methodsmentioning

confidence: 99%

The Structure and Conformation of (CH₃)₃CSNO

Cánneva

Erben

Romano

et al. 2015

Chemistry A European J

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“…S K-edge XANES shows sensitivity to changes in the 460 electronic environment of the sulfur absorber. For example, perturbation in the electron donating 461 ability of the organic moiety changes the energy positions of pre-edge features by affecting the 462 effective nuclear charge on the sulfur atom (Szilagyi and Schwab, 2005 (Figure 4b and 4c). However, monosulfides, such as S in 467 methionine and cysteine, exhibit similar spectral features and are hard to distinguish 468…”

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confidence: 99%

Stoichiometry of mercury-thiol complexes on bacterial cell envelopes

Mishra

Shoenfelt

et al. 2017

Chemical Geology

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30We have examined the speciation of Hg(II) complexed with intact cell suspensions (10 13 31 cells L -1 ) of Bacillus subtilis, a common gram-positive soil bacterium, Shewanella oneidensis 32 MR-1, a facultative gram-negative aquatic organism, and Geobacter sulfurreducens, a gram-33 negative anaerobic bacterium capable of Hg-methylation at Hg(II) loadings spanning four orders 34 of magnitude (120 nM to 350 µM) at pH 5.5 (±0.2). The coordination environments of Hg on 35 bacterial cells were analyzed using synchrotron based X-ray Absorption Near Edge Structure 36 (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy at the Hg LIII 37 edge. The abundance of thiols on intact cells was determined by a fluorescence-spectroscopy 38 based method using a soluble bromobimane, monobromo(trimethylammonio)bimane (qBBr) to 39 block thiol sites, and potentiometric titrations of biomass with and without qBBr treatment. The 40 chemical forms of S on intact bacterial cells were determined using S k-edge XANES 41 spectroscopy. 42Hg(II) was found to complex entirely with cell bound thiols at low Hg:biomass ratios. 43 For Bacillus subtilis and Shewanella oneidensis MR-1 cells, the Hg-S stoichiometry changed 44 from Hg-S3 to Hg-S2 and Hg-S (where 'S' represents a thiol site such as is present on cysteine) 45 progressively as the Hg(II) loading increased on the cells. However, Geobacter sulfurreducens 46 did not form Hg-S3 complexes. Because the abundance of thiol was highest for Geobacter 47 sulfurreducens (75 µM/g wet weight) followed by Shewanella oneidensis MR-1 (50 µM/g wet 48 weight) and Bacillus subtilis (25 µM/g wet weight), the inability of Hg(II) to form Hg-S3 49 complexes on Geobacter sulfurreducens suggests that the density and reactivity of S-amino acid 50 containing cell membrane proteins on Geobacter sulfurreducens are different from those of 51Bacillus subtilis and Shewanella oneidensis MR-1. Upon saturation of the high affinity thiol sites 52 at higher Hg:biomass ratios, Hg(II) was found to form a chelate with -hydroxy carboxylate 53anion. The stoichiometry of cell envelope bound Hg-thiol complexes and the associated 54 abundance of thiols on the cell envelopes provide important insights for understanding the 55 differences in the rate and extent of uptake and redox transformations of Hg in the environment. Introduction 66Mercury is a common contaminant found in many terrestrial and aquatic systems, and its 67 bioaccumulation in organisms, including humans, is a major environmental concern (Mergler et 68 al, 2007). The solubility, speciation, toxicity and the ultimate fate of Hg within aquatic 69 ecosystems is dependent on a large number of chemical and biological variables (Morel et al., 70 1998;Barkay and Schaefer, 2001). In aquatic systems, Hg solubility is high under oxygen-rich 71 acidic conditions but it is significantly inhibited under anoxic sulfide-rich waters (Martell and 72 Smith, 1974). The Hg-sulfide complexes are among the strongest complexes of all known Hg 73 i...

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“…pre-edge transition supported by quantitatively determining the S3p contributions. (12) (13) In particular, S K-edge XAS is selective for S3p contributions to π-bonding in RSNO-type systems. The experimentally determined nature of the SN bond in S-nitrosothiols is also in good agreement with detailed computational studies on these species.…”

Section: Introductionmentioning

confidence: 99%

The Nature of S-N Bonding in Sulfonamides and Related Compounds: Insights into π-Bonding Contributions from Sulfur K-Edge XAS

Okbinoglu¹,

Kennepohl

2020

Preprint

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Molecules containing sulfur-nitrogen bonds, like sulfonamides, have long been of interest due to their many uses and chemical properties. Understanding the factors that cause sulfonamide reactivity is important, yet their continues to be controversy regarding the relevance of S-N π bonding in describing these species. In this paper, we use sulfur K-edge x-ray absorption spectroscopy (XAS) in conjunction with density functional theory (DFT) to explore the role of S<sub>3p</sub> contributions to π-bonding in sulfonamides, sulfinamides and sulfenamides. We explore the nature of electron distribution of the sulfur atom and its nearest neighbors and extend the scope to explore the effects on rotational barriers along the sulfur-nitrogen axis. The experimental XAS data together with TD-DFT calculations confirm that sulfonamides, and the other sulfinated amides in this series, have essentially no S-N π bonding involving S<sub>3p</sub> contributions and that electron repulsion and is the dominant force that affect rotational barriers.

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Sulfur K-edge X-ray absorption spectroscopy as an experimental probe for S-nitroso proteins

Cited by 13 publications

References 48 publications

The Structure and Conformation of (CH₃)₃CSNO

The Structure and Conformation of (CH₃)₃CSNO

Stoichiometry of mercury-thiol complexes on bacterial cell envelopes

The Nature of S-N Bonding in Sulfonamides and Related Compounds: Insights into π-Bonding Contributions from Sulfur K-Edge XAS

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Sulfur K-edge X-ray absorption spectroscopy as an experimental probe for S-nitroso proteins

Cited by 13 publications

References 48 publications

The Structure and Conformation of (CH3)3CSNO

The Structure and Conformation of (CH3)3CSNO

Stoichiometry of mercury-thiol complexes on bacterial cell envelopes

The Nature of S-N Bonding in Sulfonamides and Related Compounds: Insights into π-Bonding Contributions from Sulfur K-Edge XAS

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The Structure and Conformation of (CH₃)₃CSNO

The Structure and Conformation of (CH₃)₃CSNO