Thermal fluctuations of DNA enclosed by glycerol-water glassy matrices: an elastic neutron scattering investigation.
Through elastic neutron scattering measurements, we investigated the thermal fluctuations of DNA enclosed by glycerol-water glassy matrices, at different levels of hydration, over the wide temperature range from 20 to 300 K. For all the samples, the extracted hydrogen mean square displacements (MSD) show a purely vibrational harmonic trend at very low temperatures, and a first onset of anharmonic dynamics above approximately 100 K. Such onset is consistent with the activation of DNA methyl group rotational motions. Then, at a certain temperature Td, the MSD show a second onset of anharmonicity, which corresponds to the DNA dynamical transition. The Td values vary as a function of the hydration degree of the environment. The crucial role of the solvent mobility to activate the DNA thermal fluctuations is proposed, together with a preferential hydration effect of the DNA phosphate groups. Finally, a comparison between the average mobility of homologous samples of DNA and the lysozyme protein is considered.
Cornicchi
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Dipartimento di Fisica dell'Università di Perugia, CEMIN (Centro di Eccellenza per i Materiali Innovativi Nanostrutturati) and INFM CRS-SOFT, Via Pascoli, 06123 Perugia, Italy. elena.cornicchi@fisica.unipg.it
Capponi
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Marconi
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Onori
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Paciaroni
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D000818:Animals; D004247:DNA / Q000737:chemistry*; D004548:Elasticity; D005990:Glycerol / Q000737:chemistry* / Q000494:pharmacology*; D009068:Movement / Q000187:drug effects; D009113:Muramidase / Q000737:chemistry; D033363:Neutron Diffraction; D044366:Transition Temperature; D014867:Water / Q000737:chemistry* / Q000494:pharmacology*
D014867:Water; D004247:DNA; D009113:Muramidase; D005990:Glycerol