The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Dongping Zhong - One of the best experts on this subject based on the ideXlab platform.
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dynamics and mechanism of ultrafast water protein interactions
Proceedings of the National Academy of Sciences of the United States of America, 2016Co-Authors: Lijuan Wang, Dongping ZhongAbstract:Protein hydration is essential to its structure, dynamics, and function, but water–protein interactions have not been directly observed in real time at physiological temperature to our awareness. By using a tryptophan scan with femtosecond spectroscopy, we simultaneously measured the hydration water dynamics and protein side-chain motions with temperature dependence. We observed the heterogeneous hydration dynamics around the global protein surface with two types of coupled motions, collective water/side-chain reorientation in a few Picoseconds and cooperative water/side-chain restructuring in tens of Picoseconds. The ultrafast dynamics in hundreds of femtoseconds is from the outer-layer, bulk-type mobile water molecules in the hydration shell. We also found that the hydration water dynamics are always faster than protein side-chain relaxations but with the same energy barriers, indicating hydration shell fluctuations driving protein side-chain motions on the Picosecond time scales and thus elucidating their ultimate relationship.
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Dynamics and mechanism of ultrafast water–protein interactions
Proceedings of the National Academy of Sciences, 2016Co-Authors: Yangzhong Qin, Lijuan Wang, Dongping ZhongAbstract:Protein hydration is essential to its structure, dynamics, and function, but water–protein interactions have not been directly observed in real time at physiological temperature to our awareness. By using a tryptophan scan with femtosecond spectroscopy, we simultaneously measured the hydration water dynamics and protein side-chain motions with temperature dependence. We observed the heterogeneous hydration dynamics around the global protein surface with two types of coupled motions, collective water/side-chain reorientation in a few Picoseconds and cooperative water/side-chain restructuring in tens of Picoseconds. The ultrafast dynamics in hundreds of femtoseconds is from the outer-layer, bulk-type mobile water molecules in the hydration shell. We also found that the hydration water dynamics are always faster than protein side-chain relaxations but with the same energy barriers, indicating hydration shell fluctuations driving protein side-chain motions on the Picosecond time scales and thus elucidating their ultimate relationship.
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mapping hydration dynamics around a protein surface
Proceedings of the National Academy of Sciences of the United States of America, 2007Co-Authors: Luyuan Zhang, Lijuan Wang, Yi Yang, Oghaghare Okobiah, Dongping ZhongAbstract:Protein surface hydration is fundamental to its structure and activity. We report here the direct mapping of global hydration dynamics around a protein in its native and molten globular states, using a tryptophan scan by site-specific mutations. With 16 tryptophan mutants and in 29 different positions and states, we observed two robust, distinct water dynamics in the hydration layer on a few (≈1–8 ps) and tens to hundreds of Picoseconds (≈20–200 ps), representing the initial local relaxation and subsequent collective network restructuring, respectively. Both time scales are strongly correlated with protein's structural and chemical properties. These results reveal the intimate relationship between hydration dynamics and protein fluctuations and such biologically relevant water–protein interactions fluctuate on Picosecond time scales.
D. Phillips - One of the best experts on this subject based on the ideXlab platform.
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Picosecond time resolved resonance raman observation of the iso ch2i i photoproduct from the photoisomerization reaction of diiodomethane in the solution phase
Journal of Chemical Physics, 2000Co-Authors: Wai Ming Kwok, Anthony W Parker, Michael Towrie, Pavel Matousek, David Lee Phillips, D. PhillipsAbstract:We report a preliminary Picosecond Stokes and anti-Stokes time-resolved resonance Raman (267 nm pump and 400 nm probe excitation wavelengths) investigation of the initial formation and vibrational cooling of the iso-CH2I–I photoproduct species produced after ultraviolet excitation of diiodomethane in room temperature solutions. A comparison of the Picosecond resonance Raman spectra with previously reported nanosecond transient resonance Raman spectra and density functional theory computations shows that the iso-CH2I–I photoproduct species is predominantly responsible for the ∼385 nm transient absorption band observed from several Picoseconds to nanoseconds after ultraviolet excitation of diiodomethane in the solution phase. Similar results were obtained in both nonpolar solution (cyclohexane solvent) and polar solution (acetonitrile) solvent. The Picosecond resonance Raman spectra confirm that the iso-CH2I–I photoproduct species is formed vibrationally hot within several Picoseconds and then subsequently ...
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Picosecond time-resolved resonance Raman observation of the iso-CH2I–I photoproduct from the “photoisomerization” reaction of diiodomethane in the solution phase
Journal of Chemical Physics, 2000Co-Authors: Wai Ming Kwok, Anthony W Parker, Michael Towrie, Pavel Matousek, Chensheng Ma, David Lee Phillips, D. PhillipsAbstract:We report a preliminary Picosecond Stokes and anti-Stokes time-resolved resonance Raman (267 nm pump and 400 nm probe excitation wavelengths) investigation of the initial formation and vibrational cooling of the iso-CH2I–I photoproduct species produced after ultraviolet excitation of diiodomethane in room temperature solutions. A comparison of the Picosecond resonance Raman spectra with previously reported nanosecond transient resonance Raman spectra and density functional theory computations shows that the iso-CH2I–I photoproduct species is predominantly responsible for the ∼385 nm transient absorption band observed from several Picoseconds to nanoseconds after ultraviolet excitation of diiodomethane in the solution phase. Similar results were obtained in both nonpolar solution (cyclohexane solvent) and polar solution (acetonitrile) solvent. The Picosecond resonance Raman spectra confirm that the iso-CH2I–I photoproduct species is formed vibrationally hot within several Picoseconds and then subsequently ...
Masaaki Fujii - One of the best experts on this subject based on the ideXlab platform.
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electron proton decoupling in excited state hydrogen atom transfer in the gas phase
Angewandte Chemie, 2015Co-Authors: Mitsuhiko Miyazaki, Ryuhei Ohara, Kota Daigoku, Kenro Hashimoto, Jonathan R Woodward, Claude Dedonder, Christophe Jouvet, Masaaki FujiiAbstract:Hydrogen-release by photoexcitation, excited-state-hydrogen-transfer (ESHT), is one of the important photochemical processes that occur in aromatic acids and is responsible for photoprotection of biomolecules. The mechanism is described by conversion of the initial state to a charge-separated state along the O(N)-H bond elongation, leading to dissociation. Thus ESHT is not a simple H-atom transfer in which a proton and a 1s electron move together. Here we show that the electron-transfer and the proton-motion are decoupled in gas-phase ESHT. We monitor electron and proton transfer independently by Picosecond time-resolved near-infrared and infrared spectroscopy for isolated phenol-(ammonia)5 , a benchmark molecular cluster. Electron transfer from phenol to ammonia occurred in less than 3 Picoseconds, while the overall H-atom transfer took 15 Picoseconds. The observed electron-proton decoupling will allow for a deeper understanding and control of of photochemistry in biomolecules.
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Electron–Proton Decoupling in Excited-State Hydrogen Atom Transfer in the Gas Phase
Angewandte Chemie International Edition, 2015Co-Authors: Mitsuhiko Miyazaki, Ryuhei Ohara, Kota Daigoku, Kenro Hashimoto, Jonathan R.woodward, Claude Dedonder, Christophe Jouvet, Masaaki FujiiAbstract:Hydrogen-release by photoexcitation, excited-state- hydrogen-transfer (ESHT), is one of the important photo- chemical processes that occur in aromatic acids and is responsible for photoprotection of biomolecules. The mecha- nism is described by conversion of the initial state to a charge- separated state along the O(N)-H bond elongation, leading to dissociation. Thus ESHT is not a simple H-atom transfer in which a proton and a 1s electron move together. Here we show that the electron-transfer and the proton-motion are decoupled in gas-phase ESHT. We monitor electron and proton transfer independently by Picosecond time-resolved near-infrared and infrared spectroscopy for isolated phenol–(ammonia)5, a benchmark molecular cluster. Electron transfer from phenol to ammonia occurred in less than 3 Picoseconds, while the overall H-atom transfer took 15 Picoseconds. The observed electron-proton decoupling will allow for a deeper understanding and control of of photochemistry in biomolecules
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Electron–Proton Decoupling in Excited-State Hydrogen Atom Transfer in the Gas Phase
Angewandte Chemie International Edition, 2015Co-Authors: Mitsuhiko Miyazaki, Ryuhei Ohara, Kota Daigoku, Kenro Hashimoto, Jonathan R.woodward, Claude Dedonder, Christophe Jouvet, Masaaki FujiiAbstract:Hydrogen-release by photoexcitation, excited-state- hydrogen-transfer (ESHT), is one of the important photo- chemical processes that occur in aromatic acids and is responsible for photoprotection of biomolecules. The mecha- nism is described by conversion of the initial state to a charge- separated state along the O(N)-H bond elongation, leading to dissociation. Thus ESHT is not a simple H-atom transfer in which a proton and a 1s electron move together. Here we show that the electron-transfer and the proton-motion are decoupled in gas-phase ESHT. We monitor electron and proton transfer independently by Picosecond time-resolved near-infrared and infrared spectroscopy for isolated phenol–(ammonia)5, a benchmark molecular cluster. Electron transfer from phenol to ammonia occurred in less than 3 Picoseconds, while the overall H-atom transfer took 15 Picoseconds. The observed electron-proton decoupling will allow for a deeper understanding and control of of photochemistry in biomolecules
François Hache - One of the best experts on this subject based on the ideXlab platform.
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Observation of ultrafast conformational changes in carboxy-myoglobin by time-resolved circular dichroism
2005Co-Authors: Thibault Dartigalongue, François HacheAbstract:A time-resolved circular dichroism experiment is carried out on carboxy-myoglobin. CD is measured with a sub-Picosecond time resolution after ligand dissociation. We observe a decrease of the CD signal in a few Picoseconds followed by a 100 ps relaxation towards the deoxy-myoglobin values. Thanks to a calculation developed after the polarizability theory, we are able to assign this signal to a global reorganization of the protein conformation.
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Observation of sub-100 ps conformational changes in photolyzed carbonmonoxy-myoglobin probed by time-resolved circular dichroism
Chemical Physics Letters, 2005Co-Authors: Thibault Dartigalongue, François HacheAbstract:A time-resolved circular dichroism (CD) experiment is carried out on carbonmonoxy-myoglobin. The CD is measured with a sub-Picosecond time resolution after ligand dissociation and the data are interpreted thanks to a classical CD calculation based on the polarizability theory. We observe a decrease of the CD signal in a few Picoseconds and a sub-100 ps relaxation towards steady-state deoxy-myoglobin values which we assign to a stress of the proximal histidine which relaxes with the global reorganization of the protein from its liganded geometry to its deliganded one. 2005 Elsevier B.V. All rights reserved
Wai Ming Kwok - One of the best experts on this subject based on the ideXlab platform.
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Picosecond time resolved resonance raman observation of the iso ch2i i photoproduct from the photoisomerization reaction of diiodomethane in the solution phase
Journal of Chemical Physics, 2000Co-Authors: Wai Ming Kwok, Anthony W Parker, Michael Towrie, Pavel Matousek, David Lee Phillips, D. PhillipsAbstract:We report a preliminary Picosecond Stokes and anti-Stokes time-resolved resonance Raman (267 nm pump and 400 nm probe excitation wavelengths) investigation of the initial formation and vibrational cooling of the iso-CH2I–I photoproduct species produced after ultraviolet excitation of diiodomethane in room temperature solutions. A comparison of the Picosecond resonance Raman spectra with previously reported nanosecond transient resonance Raman spectra and density functional theory computations shows that the iso-CH2I–I photoproduct species is predominantly responsible for the ∼385 nm transient absorption band observed from several Picoseconds to nanoseconds after ultraviolet excitation of diiodomethane in the solution phase. Similar results were obtained in both nonpolar solution (cyclohexane solvent) and polar solution (acetonitrile) solvent. The Picosecond resonance Raman spectra confirm that the iso-CH2I–I photoproduct species is formed vibrationally hot within several Picoseconds and then subsequently ...
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Picosecond time-resolved resonance Raman observation of the iso-CH2I–I photoproduct from the “photoisomerization” reaction of diiodomethane in the solution phase
Journal of Chemical Physics, 2000Co-Authors: Wai Ming Kwok, Anthony W Parker, Michael Towrie, Pavel Matousek, Chensheng Ma, David Lee Phillips, D. PhillipsAbstract:We report a preliminary Picosecond Stokes and anti-Stokes time-resolved resonance Raman (267 nm pump and 400 nm probe excitation wavelengths) investigation of the initial formation and vibrational cooling of the iso-CH2I–I photoproduct species produced after ultraviolet excitation of diiodomethane in room temperature solutions. A comparison of the Picosecond resonance Raman spectra with previously reported nanosecond transient resonance Raman spectra and density functional theory computations shows that the iso-CH2I–I photoproduct species is predominantly responsible for the ∼385 nm transient absorption band observed from several Picoseconds to nanoseconds after ultraviolet excitation of diiodomethane in the solution phase. Similar results were obtained in both nonpolar solution (cyclohexane solvent) and polar solution (acetonitrile) solvent. The Picosecond resonance Raman spectra confirm that the iso-CH2I–I photoproduct species is formed vibrationally hot within several Picoseconds and then subsequently ...
