Water formation reaction on Pt(111): Role of the proton transfer

2005 ◽  
Vol 122 (20) ◽  
pp. 204704 ◽  
Author(s):  
Masanari Nagasaka ◽  
Hiroshi Kondoh ◽  
Toshiaki Ohta
Keyword(s):  
Proton Transfer ◽  
Formation Reaction ◽  
Water Formation

The Role of Conserved Residues in the DEDDh Motif: the Proton-Transfer Mechanism of HIV-1 RNase H

ACS Catalysis ◽  
2021 ◽  
pp. 7915-7927
Author(s):  
Simon L. Dürr ◽  
Olga Bohuszewicz ◽  
Dénes Berta ◽  
Reynier Suardiaz ◽  
Pablo G. Jambrina ◽  
...  
Keyword(s):  
Proton Transfer ◽  
Rnase H ◽  
Transfer Mechanism ◽  
Conserved Residues ◽  
Hiv 1

scholarly journals Revealing the role of excited state proton transfer (ESPT) in excited state hydrogen transfer (ESHT): systematic study in phenol–(NH3)n clusters

2021 ◽  
Author(s):  
Christophe Jouvet ◽  
Mitsuhiko Miyazaki ◽  
Masaaki Fujii
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Systematic Study ◽  
General Model ◽  
Hydrogen Transfer ◽  
Excited State Proton Transfer

A general model of excited state hydrogen transfer (ESHT) which unifies ESHT and the excited state proton transfer (ESPT) is presented from experimental and theoretical works on phenol–(NH3)n. The hidden role of ESPT is revealed.

Role of Solvent in Excited-State Proton Transfer in Hypericin

1994 ◽  
Vol 98 (34) ◽  
pp. 8352-8358 ◽  
Author(s):  
F. Gai ◽  
M. J. Fehr ◽  
J. W. Petrich
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Excited State Proton Transfer ◽  
Role Of Solvent

Eddy Modulation of Air–Sea Interaction and Convection

2008 ◽  
Vol 38 (1) ◽  
pp. 65-83 ◽  
Author(s):  
Ivana Cerovečki ◽  
John Marshall
Keyword(s):  
Heat Flux ◽  
Heat Budget ◽  
Formation Rate ◽  
Mean Flow ◽  
Mode Water ◽  
Ocean Eddies ◽  
Eddy Heat Flux ◽  
Water Formation ◽  
Transformed Eulerian Mean

Abstract Eddy modulation of the air–sea interaction and convection that occurs in the process of mode water formation is analyzed in simulations of a baroclinically unstable wind- and buoyancy-driven jet. The watermass transformation analysis of Walin is used to estimate the formation rate of mode water and to characterize the role of eddies in that process. It is found that diabatic eddy heat flux divergences in the mixed layer are comparable in magnitude, but of opposite sign, to the surface air–sea heat flux and largely cancel the direct effect of buoyancy loss to the atmosphere. The calculations suggest that mode water formation estimates based on climatological air–sea heat flux data and outcrops, which do not fully resolve ocean eddies, may neglect a large opposing term in the heat budget and are thus likely to significantly overestimate true formation rates. In Walin’s watermass transformation framework, this manifests itself as a sensitivity of formation rate estimates to the averaging period over which the outcrops and air–sea fluxes are subjected. The key processes are described in terms of a transformed Eulerian-mean formalism in which eddy-induced mean flow tends to cancel the Eulerian-mean flow, resulting in weaker residual mean flow, subduction, and mode water formation rates.

Crystal structure of the wild-type and D30A mutant thioredoxin h of Chlamydomonas reinhardtii and implications for the catalytic mechanism

2001 ◽  
Vol 359 (1) ◽  
pp. 65-75 ◽  
Author(s):  
Valeria MENCHISE ◽  
Catherine CORBIER ◽  
Claude DIDIERJEAN ◽  
Michele SAVIANO ◽  
Ettore BENEDETTI ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Proton Transfer ◽  
Chlamydomonas Reinhardtii ◽  
Catalytic Mechanism ◽  
Structural Data ◽  
Careful Analysis ◽  
Wild Type ◽  
Thioredoxin H ◽  
Dynamics Simulations

Thioredoxins are ubiquitous proteins which catalyse the reduction of disulphide bridges on target proteins. The catalytic mechanism proceeds via a mixed disulphide intermediate whose breakdown should be enhanced by the involvement of a conserved buried residue, Asp-30, as a base catalyst towards residue Cys-39. We report here the crystal structure of wild-type and D30A mutant thioredoxin h from Chlamydomonas reinhardtii, which constitutes the first crystal structure of a cytosolic thioredoxin isolated from a eukaryotic plant organism. The role of residue Asp-30 in catalysis has been revisited since the distance between the carboxylate OD1 of Asp-30 and the sulphur SG of Cys-39 is too great to support the hypothesis of direct proton transfer. A careful analysis of all available crystal structures reveals that the relative positioning of residues Asp-30 and Cys-39 as well as hydrophobic contacts in the vicinity of residue Asp-30 do not allow a conformational change sufficient to bring the two residues close enough for a direct proton transfer. This suggests that protonation/deprotonation of Cys-39 should be mediated by a water molecule. Molecular-dynamics simulations, carried out either in vacuo or in water, as well as proton-inventory experiments, support this hypothesis. The results are discussed with respect to biochemical and structural data.

A novel assessment of the role of the methyl radical and water formation channel in the CH3OH + H reaction

2017 ◽  
Vol 19 (36) ◽  
pp. 24467-24477 ◽  
Author(s):  
Flávio O. Sanches-Neto ◽  
Nayara D. Coutinho ◽  
Valter H. Carvalho-Silva
Keyword(s):  
Atomic Hydrogen ◽  
Methyl Radical ◽  
Water Formation

A number of experimental and theoretical papers accounted almost exclusively for two channels in the reaction of atomic hydrogen with methanol. However, several astrochemical studies claimed the importance of another channel for this reaction.

scholarly journals Role of air–sea fluxes and ocean surface density in the production of deep waters in the eastern subpolar gyre of the North Atlantic

Ocean Science ◽  
2021 ◽  
Vol 17 (5) ◽  
pp. 1353-1365
Author(s):  
Tillys Petit ◽  
M. Susan Lozier ◽  
Simon A. Josey ◽  
Stuart A. Cunningham
Keyword(s):  
North Atlantic ◽  
Surface Density ◽  
Ocean Surface ◽  
Density Field ◽  
The North ◽  
Iceland Basin ◽  
Deep Waters ◽  
Water Formation ◽  
Dense Water Formation

Abstract. Wintertime convection in the North Atlantic Ocean is a key component of the global climate as it produces dense waters at high latitudes that flow equatorward as part of the Atlantic Meridional Overturning Circulation (AMOC). Recent work has highlighted the dominant role of the Irminger and Iceland basins in the production of North Atlantic Deep Water. Dense water formation in these basins is mainly explained by buoyancy forcing that transforms surface waters to the deep waters of the AMOC lower limb. Air–sea fluxes and the ocean surface density field are both key determinants of the buoyancy-driven transformation. We analyze these contributions to the transformation in order to better understand the connection between atmospheric forcing and the densification of surface water. More precisely, we study the impact of air–sea fluxes and the ocean surface density field on the transformation of subpolar mode water (SPMW) in the Iceland Basin, a water mass that “pre-conditions” dense water formation downstream. Analyses using 40 years of observations (1980–2019) reveal that the variance in SPMW transformation is mainly influenced by the variance in density at the ocean surface. This surface density is set by a combination of advection, wind-driven upwelling and surface fluxes. Our study shows that the latter explains ∼ 30 % of the variance in outcrop area as expressed by the surface area between the outcropped SPMW isopycnals. The key role of the surface density in SPMW transformation partly explains the unusually large SPMW transformation in winter 2014–2015 over the Iceland Basin.

Role of Water in Catalyzing Proton Transfer in Glucose Dehydration to 5-Hydroxymethylfurfural

ChemCatChem ◽  
2017 ◽  
Vol 9 (14) ◽  
pp. 2784-2789 ◽  
Author(s):  
Feng Zhou ◽  
Xiang Sun ◽  
Di Wu ◽  
Yugen Zhang ◽  
Haibin Su
Keyword(s):  
Proton Transfer

Isolated complexes of the amino acid arginine with polyether and polyamine macrocycles, the role of proton transfer

2017 ◽  
Vol 19 (46) ◽  
pp. 31345-31351 ◽  
Author(s):  
Juan Ramón Avilés-Moreno ◽  
Giel Berden ◽  
Jos Oomens ◽  
Bruno Martínez-Haya
Keyword(s):  
Amino Acid ◽  
Carboxylic Acid ◽  
Proton Transfer ◽  
Acid Group ◽  
Side Group ◽  
Carboxylic Acid Group

Protonated arginine interacts with 12-crown-4 through the guanidinium side group. In the complex with the N-substituted analog cyclen, the dominant conformation is the result of the proton transfer from the carboxylic acid group of the amino acid to the macrocycle.

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