Quantum behavior of water protons in protein hydration shell.
Quantum effects on the water proton dynamics over the surface of a hydrated protein are measured by means of broadband dielectric spectroscopy and deep inelastic neutron scattering. Dielectric spectroscopy indicates a reduced energy barrier for a hydrogenated protein sample compared to a deuterated one, along with a large and temperature-dependent isotopic ratio, in good agreement with theoretical studies. Recent deep inelastic neutron scattering data have been reanalyzed, and now show that the momentum distribution of water protons reflects a characteristic delocalization at ambient temperatures. These experimental findings might have far-reaching implications for enzymatic catalysis involving proton transfer processes, as in the case of the lysozyme protein studied in this report.
Pagnotta
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Centro de Fisica des Materiales, Centro Mixto CSIC-UPV/EHU, Donostia-San Sebastian, Spain.
Bruni
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F
Senesi
R
R
Pietropaolo
A
A
D000465:Algorithms; D006865:Hydrogenation; D009502:Neutrons; D011506:Proteins / Q000737:chemistry*; D011522:Protons; D012542:Scattering, Radiation; D013057:Spectrum Analysis; D013696:Temperature; D014867:Water / Q000737:chemistry*
D011506:Proteins; D011522:Protons; D014867:Water