Interaction Of H2S Research Articles

Hydrogen polysulfide (H2S n ) signaling along with hydrogen sulfide (H2S) and nitric oxide (NO).

Hydrogen sulfide (H2S) is a physiological mediator with various roles, including neuro-modulation, vascular tone regulation, and cytoprotection against ischemia-reperfusion injury, angiogenesis, and oxygen sensing. Hydrogen polysulfide (H2S n ), which possesses a higher number of sulfur atoms than H2S, recently emerged as a potential signaling molecule that regulates the activity of ion channels, a tumor suppressor, transcription factors, and protein kinases. Some of the previously reported effects of H2S are now attributed to the more potent H2S n . H2S n is produced by 3-mercaptopyruvate sulfurtransferase (3MST) from 3-mercaptopyruvate (3MP) and is generated by the chemical interaction of H2S with nitric oxide (NO). H2S n sulfhydrates (sulfurates) cysteine residues of target proteins and modifies their activity, whereas H2S sulfurates oxidized cysteine residues as well as reduces cysteine disulfide bonds. This review focuses on the recent progress made in studies concerning the production and physiological roles of H2S n and H2S.

Sulfmyoglobin conformational change: A role in the decrease of oxy-myoglobin functionality

This work is focused at understanding the interaction of H2S with Myoglobin (Mb), in particular the Sulfmyoglobin (SMb) product, whose physiological role is controversial and not well understood. The scattering curves, Guinier, Kratky, Porod and P(r) plots were analyzed for oxy-Mb and oxy-Hemoglobin I (oxyHbI) in the absence and presence of H2S, using Small and Wide Angle X-ray Scattering (SAXS/WAXS) technique. Three dimensional models were also generated from the SAXS/WAXS data. The results show that SMb formation, produced by oxyMb and H2S interaction, induces a change in the protein conformation where its envelope has a very small cleft and the protein is more flexible, less rigid and compact. Based on the direct relationship between Mb's structural conformation and its functionality, we suggest that the conformational change observed upon SMb formation plays a contribution to the protein decrease in O2 affinity and, therefore, on its functionality.

Gasotransmitters and Stomatal Closure: Is There Redundancy, Concerted Action, or Both?

Gasotransmitters and Stomatal Closure: Is There Redundancy, Concerted Action, or Both?

Influence of H2S interaction with prestrain on the mechanical properties of high-strength X80 steel

The influence of H2S interaction with prestrain on the mechanical properties of high-strength X80 steel was investigated by slow strain rate tensile tests and hydrogen content measurements. Results showed that elongation to failure first decreased and then increased with increasing prestrain. Moreover, hydrogen content decreased but the relative hydrogen embrittlement(HE) susceptibility, determined by measuring the relative reduction in failure time, increased as H2S introduction changed from the origin to the plastic stage. Fractography exhibited brittle fracture for H2S-introduced specimens and necking phenomenon decreased significantly compared with H2S-free specimens. Secondary cracks in the lateral fracture surface increased with increasing prestrain, indicating higher HE susceptibility. The observations were discussed on the basis of the hydrogen-enhanced decohesion mechanism, H2S interaction with prestrain was closely associated with mechanical property degradation.

H2S adsorption on graphene in the presence of sulfur: A density functional theory study

The high affinity of graphene for H2S makes it a potential adsorbent for separating H2S from industrial waste gas streams, and for its use in H2S sensors. The gas streams containing H2S also contain S atoms that can get bonded to graphene during adsorption. Moreover, at high temperatures, H2S dissociate at graphene defects leading to H2 desorption with S atom remaining on graphene. This study reports the effect of the presence of S atom on graphene on H2S adsorption using plane-wave density functional theory to assess the suitability of graphene-based adsorbents for continuous H2S capture. During H2S interaction with pristine graphene with S atom bonded to it, a surface cleaning mechanism was observed, where H2S exothermically removed S atom by forming H2S2. When S atom was doped in the single-vacancy defect of graphene, both physisorption and chemisorption of H2S was observed. The adsorption energy released during H2S physisorption on S-doped graphene was comparable to that for pristine graphene. However, during chemisorption, H2S dissociated on S-doped graphene to form HSSH bonded to graphene with the release of a high amount of energy. The results suggest that S atom in single-vacancy defects can enhance H2S capture on graphene.

Molecular Dynamics Simulations of Small Clusters and Liquid Hydrogen Sulfide at Different Thermodynamic Conditions.

A new force field for the intermolecular H2S-H2S interaction has been used to study the most relevant properties of the hydrogen sulfide system from gaseous to liquid phases by means of molecular dynamics (MD) simulations. In order to check the validity of the interaction formulation, ab initio CCSD(T)/aug-cc-pVTZ calculations, including the counterpoise correction on the H2S, (H2S)2, and (H2S)3 structures optimized at the MP2/aug-cc-pVDZ level, have been performed. The (H2S)2,3 systems have been characterized by performing NVE MD simulations at decreasing values of the temperature, while the liquid sulfide behavior has been investigated considering a NpT ensemble of 512 molecules at several thermodynamic states, defined by different pressure and temperature values. Additional calculations using an ensemble of 2197 molecules at two different temperatures have been performed to investigate the liquid/vapor interface of the system. The S-S, S-H, and H-H radial distribution functions and the coordination number, calculated at the same conditions used in X-ray and neutron diffraction experiments, and the evaluated thermodynamic and structural properties have been compared successfully with experimental data, thus confirming the reliability of the force field formulation and of the MD predictions.

H2S- and NO-Signaling Pathways in Alzheimer's Amyloid Vasculopathy: Synergism or Antagonism?

Alzheimer's type of neurodegeneration dramatically affects H2S and NO synthesis and interactions in the brain, which results in dysregulated vasomotor function, brain tissue hypoperfusion and hypoxia, development of perivascular inflammation, promotion of Aβ deposition, and impairment of neurogenesis/angiogenesis. H2S- and NO-signaling pathways have been described to offer protection against Alzheimer's amyloid vasculopathy and neurodegeneration. This review describes recent developments of the increasing relevance of H2S and NO in Alzheimer's disease (AD). More studies are however needed to fully determine their potential use as therapeutic targets in Alzheimer's and other forms of vascular dementia.

At the Molecular Level through Photophysical Studies: Structural Implications on the Reactivity of Dual-Site Sensitive Positional Isomers Toward a Gasotransmitter (H2S)

A combined experimental and theoretical approach has enabled us to understand at the molecular level the importance of positional and electronic effects of chemical functionality present in molecular system that acts as an optical signaling agent. The present study demonstrates the structural implications of isomeric dual-site reactive (nitro and sulfonte ester groups) molecular probes (P1, P2, and P3) on optical signaling of hydrogen sulfide (H2S), a known emerging mediator in human physiological activities and diseases. The reactivity of these probes toward H2S was established using fluorescence signaling studies. The reductive interaction of H2S with nitro functionality of P2 resulted in the formation of orange fluorescent amine derivative P2′, while the nucleophilic S–O bond cleavage of sulfonate ester group of P3 produced sulfonothionic acid derivative P3′ as a green emissive fluorescent species. Crystal structure determination and structure–reactivity relationship studies demonstrated positional as well as electronic effects of nitro functionality on the reactivity of these probes. While the electronic effect is responsible for increasing the reactivity of sulfonate functionality, the accessibility of the reactive site by H2S is dictated by the steric factor. Although both −M (mesomeric) and −I (inductive) effects of nitro functionality are supposed to be prominent in P1 and P3, crystal structure analysis revealed a steric crowding on P1created by nitro group as well as out-of-plane arrangement of nitro group, which in turn makes P1 much less reactive than P3. In the case of P2, the probe is free from steric effect, but the weak −I effect and the absence of −M effect made sulfonate functionality nonreactive toward H2S. At the same time, slow reductive interaction of nitro group of P2 yielded orange emissive fluorescent species P2′.

Fast Response and High Sensitivity of ZnO Nanowires-Cobalt Phthalocyanine Heterojunction Based H2S Sensor.

The room temperature chemiresistive response of n-type ZnO nanowire (ZnO NWs) films modified with different thicknesses of p-type cobalt phthalocyanine (CoPc) has been studied. With increasing thickness of CoPc (>15 nm), heterojunction films exhibit a transition from n- to p-type conduction due to uniform coating of CoPc on ZnO. The heterojunction films prepared with a 25 nm thick CoPc layer exhibit the highest response (268% at 10 ppm of H2S) and the fastest response (26 s) among all samples. The X-ray photoelectron spectroscopy and work function measurements reveal that electron transfer takes place from ZnO to CoPc, resulting in formation of a p-n junction with a barrier height of 0.4 eV and a depletion layer width of ∼8.9 nm. The detailed XPS analysis suggests that these heterojunction films with 25 nm thick CoPc exhibit the least content of chemisorbed oxygen, enabling the direct interaction of H2S with the CoPc molecule, and therefore exhibit the fastest response. The improved response is attributed to the high susceptibility of the p-n junctions to the H2S gas, which manipulates the depletion layer width and controls the charge transport.

Hydrogen peroxide might be a downstream signal molecule of hydrogen sulfide in seed germination of mung bean (Vigna radiata)

AbstractHydrogen sulfide (H

Predicting H2S Oxidative Dehydrogenation over Graphene Oxides from First Principles

Spin-polarized periodic density functional theory was performed to characterize H2S adsorption and dissociation on graphene oxides (GO) surface. The comprehensive reaction network of H2S oxidation with epoxy and hydroxyl groups of GO was discussed. It is shown that the reduction reaction is mainly governed by epoxide ring opening and hydroxyl hydrogenation which is initiated by H transfer from H2S or its derivatives. Furthermore, the presence of another OH group at the opposite side relative to the adsorbed H2S activates the oxygen group to facilitate epoxide ring opening and hydroxyl hydrogenation. For H2S interaction with -O and -OH groups adsorption on each side of graphene, the pathway is a favorable reaction path by the introduction of intermediate states, the predicted energy barriers are 3.2 and 10.4 kcal/mol, respectively, the second H transfer is the rate-determining step in the whole reaction process. In addition, our calculations suggest that both epoxy and hydroxyl groups can enhance the binding of S to the C—C bonds and the effect of hydroxyl group is more local than that of the epoxy.

Seasonal changes in infaunal community structure in a hypertrophic brackish canal: Effects of hypoxia, sulfide, and predator–prey interaction

We conducted a one-year survey of macrozoobenthic community structure at 5 stations in a eutrophic canal in inner Tokyo Bay, focusing on the impacts of hypoxia, sediment H2S, and species interaction in the littoral soft-bottom habitats. Complete defaunation or decreasing density of less-tolerant taxa occurred under hypoxia during warmer months, especially at subtidal or sulfidic stations; this was followed by rapid recolonization by opportunistic polychaetes in fall–winter. Sedimentary H2S increased the mortality of macroinvertebrates under hypoxia or delayed population recovery during recolonization. The density of several polychaetes (e.g., Pseudopolydora reticulata) declined in winter, coincident with immigration of the predator Armandia lanceolata. This suggests that absence of A. lanceolata under moderate hypoxia enabled the proliferation of prey taxa. We conclude that oxygen concentration, sediment H2S, and hypoxia-induced changes in species interactions are potential drivers for spatiotemporal changes in macrozoobenthic assemblage structure in hypoxia-prone soft-bottom communities.

H2S interaction with HKUST-1 and ZIF-8 MOFs: A multitechnique study

The interaction of H2S with HKUST-1 and ZIF-8 MOFs has been studied by means of FT-IR, Raman, DRUV-Vis-NIR and PXRD techniques. At very low equilibrium pressure (below 5 mbar) a stepwise structural distortion is observed in both HKUST-1 and ZIF-8. At higher equilibrium pressures (20–60 mbar), PXRD technique, in particular, showed the structural destruction of HKUST-1 with formation of a covallite (CuS) phase and some structural distortion of ZIF-8.

Interaction of H2O and H2S with Cu(111) and the impact of the electric field: the rotating & translating adsorbate, and the rippled surface.

The interactions of H2O and H2S monomers with Cu(111) in the absence and presence of an external electric field are studied using density functional theory. It is found that the adsorption is accompanied by a rippled pattern of the surface Cu atoms and electron accumulation on the surface Cu atoms surrounding the adsorption site. The response of the H2O/Cu(111) and H2S/Cu(111) interfaces to the external electric field is computed up to the field magnitude of 10(10) V m(-1). The results show that H2O rotates and translates much more with an electric field than H2S does. The extent of the surface deformation changes considerably with the applied electric field, which influences the translation pattern of the adsorbates. On the other hand, the rotation of the adsorbates is correlated to the dipole moment of the molecules and their adsorption energies.

H2S in the Vasculature: Controversy of Mechanisms in Physiology, Pathology and Beyond

Hydrogen sulfide (H2S) is an endogenously gaseous messenger with a number of physiological effects. Pharmacological and genetic models point toward an important role for this vasodilator gas in the regulation of vascular tone, cardiac response to ischemia/reperfusion injury, and inflammation among others. Understanding the complex interaction of H2S with basic cellular signaling and its impact on endothelial and smooth muscle physiology may provide insights into the early stages of developing vascular inflammation and atherosclerosis or related vascular pathologies. The underlying mechanism of action is not completely understood. Recent evidence suggests a key role of H2S in protecting mitochondria against oxidative damage, regulation of ion channels and modulation of eNOS activity. This review will focus on the key role of H2S in the regulation of vascular function including free radical production and its physiological role in health and disease

O–S Bond Activation in Structures Isoelectronic with Ferric Peroxide Species Known in O–O‐Activating Enzymes: Relevance for Sulfide Activation and Sulfite Reductases

AbstractThe interactions of H2S with FeIVO porphyrin radical‐cation structures and of peroxide‐like H2OS systems with ferric heme have been investigated by DFT. The data are relevant for the formation of sulfheme in globins and for the catalytic cycle of sulfite reductases. Heme FeOS systems (and their protonated versions) feature relatively accessible potential energy surfaces for O–S bond formation and cleavage, and for the insertion of S at the meso position of the heme; O–S bond cleavage is thermodynamically favorable only in diprotonated versions of the FeOS unit, FeIVO + H2S, or the ferric–HOSH isomer. The insertion at the meso position is reminiscent of heme oxygenase meso‐hydroxylation via a ferric–hydroperoxo intermediate. Although axial imidazole and methylthiolate yield similar reaction profiles in all themodels studied, the FeIVO + H2S reaction is another case of our previously advocated “thiolate obstruction”, in which thiolate hinders rather than favors reactions at the heme center.

Interaction of H2S with ZrO2 and its influence on reactivity of surface oxygen

ZrO2 catalysts can be efficiently applied to convert tars into less harmful compounds in biomass gasification gas clean-up, also in the presence of H2S. In fact, H2S has even been observed to enhance naphthalene (a model compound for tar) oxidation activity on ZrO2. Sulfur binding and its effect on the reactivity of surface oxygen species, including OH groups as well surface lattice oxygen, on ZrO2 was studied using temperature-programmed methods. At 30°C approx. half of the adsorbed H2S was physisorbed and the other part dissociated titrating terminal OH groups. This dissociated H2S was strongly adsorbed. Moreover, it was found that after treatment with H2S until 400°C half of the adsorbed species were irreversibly adsorbed. H2S adsorbed inducing desorption of water at two distinct temperatures (∼170 and 280°C) during temperature ramp. Thus, H2S adsorption at elevated temperatures produced surface sulfur by replacement of surface lattice oxygen at two types of minority sites (max. 5% of a monolayer). Therefore we suggest that multicoordinated OH groups and surface lattice oxygen at defective sites are involved. CO-TPR revealed increased reactivity of surface lattice oxygen on ZrO2 with increasing amount of sulfur on the surface. In addition, strong adsorption of carbonates was suppressed by the presence of sulfur. The observed H2S-induced enhancement of naphthalene oxidation in gasification gas clean-up is suggested to be caused by the increased reactivity of surface oxygen species in the vicinity of sulfur species on the surface.

DFT study of adsorption and dissociation behavior of H2S on Fe-doped graphene

Understanding the interaction mechanisms of hydrogen sulfide (H2S) with graphene is important in developing graphene-based sensors for gas detection and removal. In this study, the effects of doped Fe atom on interaction of H2S with graphene were investigated by density functional theory calculations. Analyses of adsorption energy, electron density difference, and density of states indicated that the doped Fe atom can significantly improve the interaction of H2S gas molecules with graphene, as well as Pt-doped graphene. The location of the sulfur atom is important in the interactions between H2S and Fe-doped graphene. The influence of the FeS distance can be very weak within a certain distance, as simulated in this study.

Hydrogen Sulfide Detection Using a Gold Nanoparticle/Metalloprotein Based Probe

We present a simple method for direct detection of hydrogen sulfide (H2S) in an aqueous solution. This method represents a novel biosensor based on metalloprotein cytochrome c (cyt c) with the localized surface plasmon resonance of gold nanoparticles (AuNPs). For this purpose, we develop a new approach based on attaching chemically-modified cyt c onto AuNPs. Here, by reacting H2S with protein heme center, its conformation changes in the locality of the heme moiety. The conformational changes occurring in the protein alter the spectral characteristics by changing the dielectric properties of AuNPs. The conformational changes of cyt c induced by the H2S interaction are characterized by the UV-visible absorption spectroscopy and the circular dichroism technique. The limit of the detection and sensitivity of the AuNPs/cyt c biosensor are evaluated by using UV-visible spectroscopy. According to the experiments, it is revealed that H2S can be detected at a concentration of 4.0 μM (1.3 ppb) by the fabricated AuNPs/cyt c biosensor. In addition, the sensor retains activity and gives reproducible results after storage in 4°C for 60 d. This simple and cost-effective sensing platform provides a rapid and convenient detection for H2S at concentrations far below the hazardous limit.

The therapeutic potential of cystathionine β-synthetase/hydrogen sulfide inhibition in cancer.

Cancer represents a major socioeconomic problem; there is a significant need for novel therapeutic approaches targeting tumor-specific pathways. In colorectal and ovarian cancers, an increase in the intratumor production of hydrogen sulfide (H2S) from cystathionine β-synthase (CBS) plays an important role in promoting the cellular bioenergetics, proliferation, and migration of cancer cells. It also stimulates peritumor angiogenesis inhibition or genetic silencing of CBS exerts antitumor effects both in vitro and in vivo, and potentiates the antitumor efficacy of anticancer therapeutics. Recently published studies are reviewed, implicating CBS overexpression and H2S overproduction in tumor cells as a tumor-growth promoting "bioenergetic fuel" and "survival factor," followed by an overview of the experimental evidence demonstrating the anticancer effect of CBS inhibition. Next, the current state of the art of pharmacological CBS inhibitors is reviewed, with special reference to the complex pharmacological actions of aminooxyacetic acid. Finally, new experimental evidence is presented to reconcile a controversy in the literature regarding the effects of H2S donor on cancer cell proliferation and survival. From a basic science standpoint, future directions in the field include the delineation of the molecular mechanism of CBS up-regulation of cancer cells and the delineation of the interactions of H2S with other intracellular pathways of cancer cell metabolism and proliferation. From the translational science standpoint, future directions include the translation of the recently emerging roles of H2S in cancer into human diagnostic and therapeutic approaches.