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Full-Text Articles in Life Sciences
Down To Atomic-Scale Intracellular Water Dynamics, M. Jasnin, M. Moulin, M. Haertlein, G. Zaccai, M. Tehei
Down To Atomic-Scale Intracellular Water Dynamics, M. Jasnin, M. Moulin, M. Haertlein, G. Zaccai, M. Tehei
Faculty of Science - Papers (Archive)
Water constitutes the intracellular matrix in which biological molecules interact. Understanding its dynamic state is a main scientific challenge, which continues to provoke controversy after more than 50 years of study. We measured water dynamics in vivo in the cytoplasm of Escherichia coli by using neutron scattering and isotope labelling. Experimental timescales covered motions from pure water to interfacial water, on an atomic length scale. In contrast to the widespread opinion that water is ‘tamed’ by macromolecular confinement, the measurements established that water diffusion within the bacteria is similar to that of pure water at physiological temperature.
In Vivo Measurement Of Internal And Global Macromolecular Motions In E. Coli, M. Jasnin, M. Moulin, M. Haertlein, G. Zaccai, M. Tehei
In Vivo Measurement Of Internal And Global Macromolecular Motions In E. Coli, M. Jasnin, M. Moulin, M. Haertlein, G. Zaccai, M. Tehei
Faculty of Science - Papers (Archive)
We present direct quasielastic neutron scattering measurements, in vivo, of macromolecular dynamics in E. coli. The experiments were performed on a wide range of time-scales, to cover the large panel of internal and self-diffusion motions. Three major internal processes were extracted at physiological temperature: a fast picosecond (ps) process that corresponded to restricted jump diffusion motions, and two slower processes that resulted from reorientational motions occurring in about 40 ps and 90 ps, respectively. The analysis of the fast process revealed that the cellular environment leads to an appreciable increase in internal molecular flexibility and diffusive motion rates compared to …
Solvent Isotope Effect On Macromolecular Dynamics In E. Coli, M. Jasnin, M. Tehei, M. Moulin, M. Haertlein, G. Zaccai
Solvent Isotope Effect On Macromolecular Dynamics In E. Coli, M. Jasnin, M. Tehei, M. Moulin, M. Haertlein, G. Zaccai
Faculty of Science - Papers (Archive)
Elastic incoherent neutron scattering was used to explore solvent isotope effects on average macromolecular dynamics in vivo. Measurements were performed on living E. coli bacteria containing H2O and D2O, respectively, close to physiological conditions of temperature. Global macromolecular flexibility, expressed as mean square fluctuation (MSF) values, and structural resilience in a free energy potential, expressed as a mean effective force constant, hk0i, were extracted in the two solvent conditions. They referred to the average contribution of all macromolecules inside the cell, mostly dominated by the internal motions of the protein fraction. Flexibility and resilience were both found to be smaller …
From Shell To Cell: Neutron Scattering Studies Of Biological Water Dynamics And Coupling To Activity, A. Frölich, F. Gabel, M. Jasnin, U. Lehnert, D. Oesterhelt, A. Stadler, M. Tehei, M. Weik, K. Wood, G. Zaccai
From Shell To Cell: Neutron Scattering Studies Of Biological Water Dynamics And Coupling To Activity, A. Frölich, F. Gabel, M. Jasnin, U. Lehnert, D. Oesterhelt, A. Stadler, M. Tehei, M. Weik, K. Wood, G. Zaccai
Faculty of Science - Papers (Archive)
An integrated picture of hydration shell dynamics and of its coupling to functional macromolecular motions is proposed from studies on a soluble protein, on a membrane protein in its natural lipid environment, and on the intracellular environment in bacteria and red blood cells. Water dynamics in multimolar salt solutions was also examined, in the context of the very slow water component previously discovered in the cytoplasm of extreme halophilic archaea. The data were obtained from neutron scattering by using deuterium labelling to focus on the dynamics of different parts of the complex systems examined.