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Full-Text Articles in Physical Sciences and Mathematics
Fundamental And Biotechnological Applications Of Neutron Scattering Measurements For Macromolecular Dynamics, M. Tehei, R. Daniel, G. Zaccai
Fundamental And Biotechnological Applications Of Neutron Scattering Measurements For Macromolecular Dynamics, M. Tehei, R. Daniel, G. Zaccai
Faculty of Science - Papers (Archive)
To explore macromolecular dynamics on the picosecond timescale, we used neutron spectroscopy. First, molecular dynamics were analyzed for the hyperthermophile malate dehydrogenase from Methanococcus jannaschii and a mesophilic homologue, the lactate dehydrogenase from Oryctolagus cunniculus muscle. Hyperthermophiles have elaborate molecular mechanisms of adaptation to extremely high temperature. Using a novel elastic neutron scattering approach that provides independent measurements of the global flexibility and of the structural resilience (rigidity), we have demonstrated that macromolecular dynamics represents one of these molecular mechanisms of thermoadaptation. The flexibilities were found to be similar for both enzymes at their optimal activity temperature and the resilience …
Dynamics Of Immobilized And Native Escherichia Coli Dihydrofolate Reductase By Quasielastic Neutron Scattering, M. Tehei, J. Smith, C. Monk, J. Ollivier, M. Oettl, V. Kurkal, J. L. Finney, R. M. Daniel
Dynamics Of Immobilized And Native Escherichia Coli Dihydrofolate Reductase By Quasielastic Neutron Scattering, M. Tehei, J. Smith, C. Monk, J. Ollivier, M. Oettl, V. Kurkal, J. L. Finney, R. M. Daniel
Faculty of Science - Papers (Archive)
The internal dynamics of native and immobilized Escherichia coli dihydrofolate reductase (DHFR) have been examined using incoherent quasielastic neutron scattering. These results reveal no difference between the high frequency vibration mean-square displacement of the native and the immobilized E. coli DHFR. However, length-scale-dependent, picosecond dynamical changes are found. On longer length scales, the dynamics are comparable for both DHFR samples. On shorter length scales, the dynamics is dominated by local jump motions over potential barriers. The residence time for the protons to stay in a potential well is t=7.95 ps for the native DHFR and t=20.36 ps for the immobilized …
Structure And Dynamics Of Sponge-Dominated Assemblages On Exposed And Sheltered Temperate Reefs, D. E. Roberts, S. P. Cummins, A. R. Davis, M. G. Chapman
Structure And Dynamics Of Sponge-Dominated Assemblages On Exposed And Sheltered Temperate Reefs, D. E. Roberts, S. P. Cummins, A. R. Davis, M. G. Chapman
Faculty of Science - Papers (Archive)
There have been few studies on the structure and dynamics of sponge-dominated assemblages, despite the fact that such assemblages are vulnerable to environmental impacts from many anthropogenic disturbances. Sponges are generally slow to recruit, slow growing and long lived; hence, they may be very vulnerable to anthropogenic and natural disturbances. In order to understand how such assemblages may respond to disturbance, it is essential to measure natural patterns of spatial differences and temporal changes, so that any future impact assessments can be identified. This study quantified and contrasted patterns of abundance in sponge-dominated assemblages on deep reefs (18 to 20 …