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Incoherent neutron scattering of copper azurin: A comparison with molecular dynamics simulation results

TitoloIncoherent neutron scattering of copper azurin: A comparison with molecular dynamics simulation results
Tipo di pubblicazioneArticolo su Rivista peer-reviewed
Anno di Pubblicazione1999
AutoriPaciaroni, A., Stroppolo M.E., Arcangeli Caterina, Bizzarri A.R., Desideri A., and Cannistraro S.
RivistaEuropean Biophysics Journal
Volume28
Paginazione447-456
ISSN01757571
Parole chiavearticle, azurin, Bacterial Proteins, Computer simulation, Copper, copper derivative, Escherichia coli, Hydration, Models, Molecular, molecular dynamics, neutron scattering, Protein Structure, Pseudomonas aeruginosa, Radiation, Scattering, simulation, Temperature, Water
Abstract

The low-frequency dynamics of copper azurin has been studied at different temperatures for a dry and deuterium hydrated sample by incoherent neutron scattering and the experimental results have been compared with molecular dynamics (MD) simulations carried out in the same temperature range. Experimental Debye-Waller factors are consistent with a dynamical transition at approximately 200 K which appears partially suppressed in the dry sample. Inelastic and quasielastic scattering indicate that hydration water modulates both vibrational and diffusive motions. The low-temperature experimental dynamical structure factor of the hydrated protein shows an excess of inelastic scattering peaking at about 3 meV and whose position is slightly shifted downwards in the dry sample. Such an excess is reminiscent of the 'boson peak' observed in glass-like materials. This vibrational peak is quite well reproduced by MD simulations, although at a lower energy. The experimental quasielastic scattering of the two samples at 300 K shows a two- step relaxation behaviour with similar characteristic times, while the corresponding intensities differ only by a scale factor. Also, MD simulations confirm the two-step diffusive trend, but the slow process seems to be characterized by a decay faster than the experimental one. Comparison with incoherent neutron scattering studies carried out on proteins having different structure indicates that globular proteins display common elastic, quasielastic and inelastic features, with an almost similar hydration dependence, irrespective of their secondary and tertiary structure.

Note

cited By 40

URLhttps://www.scopus.com/inward/record.uri?eid=2-s2.0-0032873476&doi=10.1007%2fs002490050227&partnerID=40&md5=a3baf36cd84d9ae737f8287e15338aae
DOI10.1007/s002490050227
Citation KeyPaciaroni1999447