Search results for "protein dynamics"
showing 10 items of 61 documents
Chemical Ligation and Isotope Labeling to Locate Dynamic Effects during Catalysis by Dihydrofolate Reductase.
2015
Abstract Chemical ligation has been used to alter motions in specific regions of dihydrofolate reductase from E. coli and to investigate the effects of localized motional changes on enzyme catalysis. Two isotopic hybrids were prepared; one with the mobile N‐terminal segment containing heavy isotopes (2H, 13C, 15N) and the remainder of the protein with natural isotopic abundance, and the other one with only the C‐terminal segment isotopically labeled. Kinetic investigations indicated that isotopic substitution of the N‐terminal segment affected only a physical step of catalysis, whereas the enzyme chemistry was affected by protein motions from the C‐terminal segment. QM/MM studies support th…
Dynamics of protein-water systems revealed by Rayleigh scattering of Mössbauer radiation (RSMR)
1990
A critical review of recent studies of protein dynamics by the RSMR technique is given. The main approximations in quantitative analyses of RSMR data are discussed and conclusions about dynamical properties of protein and interprotein water, deduced from experiments, are described.
Proteins in Saccharides Matrices and the Trehalose Peculiarity: Biochemical and Biophysical Properties
2015
Immobilization of proteins and other biomolecules in saccharide matrices leads to a series of peculiar properties that are relevant from the point of view of both biochemistry and biophysics, and have important implications on related fields such as food industry, pharmaceutics, and medicine. In the last years, the properties of biomolecules embedded into glassy matrices and/or highly concentrated solutions of saccharides have been thoroughly investigated, at the molecular level, through in vivo, in vitro, and in silico studies. These systems show an outstanding ability to protect biostructures against stress conditions; various mechanisms appear to be at the basis of such bioprotection, th…
Unveiling the timescale of the R-T transition in human hemoglobin.
2010
Time-resolved wide-angle X-ray scattering, a recently developed technique allowing to probe global structural changes of proteins in solution, was used to investigate the kinetics of R-T quaternary transition in human hemoglobin and to systematically compare it to that obtained with time-resolved optical spectroscopy under nearly identical experimental conditions. Our data reveal that the main structural rearrangement associated with the R-T transition takes place approximately 2 mus after the photolysis of hemoglobin at room temperature and neutral pH. This finding suggests that the 20-mus step observed with time-resolved optical spectroscopy corresponds to a small and localized structural…
Probing light-induced conformational transitions in bacterial photosynthetic reaction centers embedded in trehalose-water amorphous matrices.
2004
Abstract The coupling between electron transfer and protein dynamics has been studied in photosynthetic reaction centers (RC) from Rhodobacter sphaeroides by embedding the protein into room temperature solid trehalose–water matrices. Electron transfer kinetics from the primary quinone acceptor (Q A − ) to the photoxidized donor (P + ) were measured as a function of the duration of photoexcitation from 20 ns (laser flash) to more than 1 min. Decreasing the water content of the matrix down to ≈5×10 3 water molecules per RC causes a reversible four-times acceleration of P + Q A − recombination after the laser pulse. By comparing the broadly distributed kinetics observed under these conditions …
Myoglobin embedded in saccharide amorphous matrices: water-dependent domains evidenced by small angle X-ray scattering
2010
We report Small Angle X-ray Scattering (SAXS) measurements performed on samples of carboxy-myoglobin (MbCO) embedded in low-water trehalose glasses. Results showed that, in such samples, "low-protein" trehalose-water domains are present, surrounded by a protein-trehalose-water background; such finding is supported by Infrared Spectroscopy (FTIR) measurements. These domains, which do not appear in the absence of the protein and in analogous sucrose systems, preferentially incorporate the incoming water at the onset of rehydration, and disappear following large hydration. This observation suggests that, in organisms under anhydrobiosis, analogous domains could play a buffering role against th…
The impact of high hydrostatic pressure on structure and dynamics of beta-lactoglobulin
2013
Abstract Methods Combining small-angle X-ray and neutron scattering measurements with inelastic neutron scattering experiments, we investigated the impact of high hydrostatic pressure on the structure and dynamics of β-lactoglobulin (βLG) in aqueous solution. Background βLG is a relatively small protein, which is predominantly dimeric in physiological conditions, but dissociates to monomer below about pH 3. Results High-pressure structural results show that the dimer–monomer equilibrium, as well as the protein–protein interactions, are only slightly perturbed by pressure, and βLG unfolding is observed above a threshold value of 3000 bar. In the same range of pressure, dynamical results put …
Conformational substates and dynamic properties of carbonmonoxy hemoglobin.
2003
Heme pocket dynamics of human carbonmonoxy hemoglobin (HbCO) is studied by Fourier transform infrared spectroscopy. The CO stretching band at various temperatures in the interval 300-10 K is analyzed in terms of three taxonomic A substates; however, in HbCO the band attributed to the A(1) taxonomic substate accounts for approximately 90% of the total intensity in the pH range 8.8-4.5. Two different regimes as a function of temperature are observed: below 160 K, the peak frequency and the bandwidth of the A(1) band have constant values whereas, above this temperature, a linear temperature dependence is observed, suggesting the occurrence of transitions between statistical substates within th…
Conformation and concerted dynamics of the integrin-binding site and the C-terminal region of echistatin revealed by homonuclear NMR
2005
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Insights into amyloid fibrils dynamics from neutron scattering
2011
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