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Proton transport

About: Proton transport is a research topic. Over the lifetime, 5676 publications have been published within this topic receiving 221793 citations.


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Journal ArticleDOI
20 Aug 1999-Science
TL;DR: Overexpression of a vacuolar Na+/H+ antiport fromArabidopsis thaliana in Arabidopsis plants promotes sustained growth and development in soil watered with up to 200 millimolar sodium chloride, demonstrating the feasibility of engineering salt tolerance in plants.
Abstract: Agricultural productivity is severely affected by soil salinity. One possible mechanism by which plants could survive salt stress is to compartmentalize sodium ions away from the cytosol. Overexpression of a vacuolar Na+/H+antiport from Arabidopsis thaliana in Arabidopsisplants promotes sustained growth and development in soil watered with up to 200 millimolar sodium chloride. This salinity tolerance was correlated with higher-than-normal levels of AtNHX1transcripts, protein, and vacuolar Na+/H+(sodium/proton) antiport activity. These results demonstrate the feasibility of engineering salt tolerance in plants.

1,882 citations

Journal ArticleDOI
TL;DR: In this article, the authors apply the surface-hopping method to proton transfer in solution, where the quantum particle is an atom, using full classical mechanical molecular dynamics for the heavy atom degrees of freedom, including the solvent molecules.
Abstract: We apply ‘‘molecular dynamics with quantum transitions’’ (MDQT), a surface‐hopping method previously used only for electronic transitions, to proton transfer in solution, where the quantum particle is an atom. We use full classical mechanical molecular dynamics for the heavy atom degrees of freedom, including the solvent molecules, and treat the hydrogen motion quantum mechanically. We identify new obstacles that arise in this application of MDQT and present methods for overcoming them. We implement these new methods to demonstrate that application of MDQT to proton transfer in solution is computationally feasible and appears capable of accurately incorporating quantum mechanical phenomena such as tunneling and isotope effects. As an initial application of the method, we employ a model used previously by Azzouz and Borgis to represent the proton transfer reaction AH–B■A−–H+B in liquid methyl chloride, where the AH–B complex corresponds to a typical phenol–amine complex. We have chosen this model, in part, because it exhibits both adiabatic and diabatic behavior, thereby offering a stringent test of the theory. MDQT proves capable of treating both limits, as well as the intermediate regime. Up to four quantum states were included in this simulation, and the method can easily be extended to include additional excited states, so it can be applied to a wide range of processes, such as photoassisted tunneling. In addition, this method is not perturbative, so trajectories can be continued after the barrier is crossed to follow the subsequent dynamics.

1,150 citations

Journal ArticleDOI
28 Jun 2002-Science
TL;DR: A complementary DNA sequence in the green alga Chlamydomonas reinhardtiithat encodes a microbial opsin-related protein, which is suggested to be Channelopsin-1, which shows homology to the light-activated proton pump bacteriorhodopsin.
Abstract: Phototaxis and photophobic responses of green algae are mediated by rhodopsins with microbial-type chromophores. We report a complementary DNA sequence in the green alga Chlamydomonas reinhardtii that encodes a microbial opsin-related protein, which we term Channelopsin-1. The hydrophobic core region of the protein shows homology to the light-activated proton pump bacteriorhodopsin. Expression of Channelopsin-1, or only the hydrophobic core, in Xenopus laevis oocytes in the presence of all-trans retinal produces a light-gated conductance that shows characteristics of a channel selectively permeable for protons. We suggest that Channelrhodopsins are involved in phototaxis of green algae.

1,107 citations

Journal ArticleDOI
31 Jan 2008-Nature
TL;DR: The structure of the tetrameric M2 channel in complex with rimantadine, determined by NMR is presented and predicted to counter the effect of drug binding by either increasing the hydrophilicity of the pore or weakening helix–helix packing, thus facilitating channel opening.
Abstract: The integral membrane protein M2 of influenza virus forms pH-gated proton channels in the viral lipid envelope. The low pH of an endosome activates the M2 channel before haemagglutinin-mediated fusion. Conductance of protons acidifies the viral interior and thereby facilitates dissociation of the matrix protein from the viral nucleoproteins--a required process for unpacking of the viral genome. In addition to its role in release of viral nucleoproteins, M2 in the trans-Golgi network (TGN) membrane prevents premature conformational rearrangement of newly synthesized haemagglutinin during transport to the cell surface by equilibrating the pH of the TGN with that of the host cell cytoplasm. Inhibiting the proton conductance of M2 using the anti-viral drug amantadine or rimantadine inhibits viral replication. Here we present the structure of the tetrameric M2 channel in complex with rimantadine, determined by NMR. In the closed state, four tightly packed transmembrane helices define a narrow channel, in which a 'tryptophan gate' is locked by intermolecular interactions with aspartic acid. A carboxy-terminal, amphipathic helix oriented nearly perpendicular to the transmembrane helix forms an inward-facing base. Lowering the pH destabilizes the transmembrane helical packing and unlocks the gate, admitting water to conduct protons, whereas the C-terminal base remains intact, preventing dissociation of the tetramer. Rimantadine binds at four equivalent sites near the gate on the lipid-facing side of the channel and stabilizes the closed conformation of the pore. Drug-resistance mutations are predicted to counter the effect of drug binding by either increasing the hydrophilicity of the pore or weakening helix-helix packing, thus facilitating channel opening.

989 citations

Journal ArticleDOI
27 Jun 2002-Nature
TL;DR: The solution structures and transport mechanisms of hydrated hydroxide are reported from first-principles computer simulations that explicitly treat quantum and thermal fluctuations of all nuclei and find that the transport mechanism differs significantly from the proton hole picture.
Abstract: Compared to other ions, protons (H+) and hydroxide ions (OH-) exhibit anomalously high mobilities in aqueous solutions1. On a qualitative level, this behaviour has long been explained by ‘structural diffusion’—the continuous interconversion between hydration complexes driven by fluctuations in the solvation shell of the hydrated ions. Detailed investigations have led to a clear understanding of the proton transport mechanism at the molecular level2,3,4,5,6,7,8. In contrast, hydroxide ion mobility in basic solutions has received far less attention2,3,9,10, even though bases and base catalysis play important roles in many organic and biochemical reactions and in the chemical industry. The reason for this may be attributed to the century-old notion11 that a hydrated OH- can be regarded as a water molecule missing a proton, and that the transport mechanism of such a ‘proton hole’ can be inferred from that of an excess proton by simply reversing hydrogen bond polarities11,12,13,14,15,16,17,18. However, recent studies2,3 have identified OH- hydration complexes that bear little structural similarity to proton hydration complexes. Here we report the solution structures and transport mechanisms of hydrated hydroxide, which we obtained from first-principles computer simulations that explicitly treat quantum and thermal fluctuations of all nuclei19,20,21. We find that the transport mechanism, which differs significantly from the proton hole picture, involves an interplay between the previously identified hydration complexes2,3 and is strongly influenced by nuclear quantum effects.

835 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202364
2022121
2021198
2020213
2019173
2018161