Temperature dependence of fast fluctuations in single- and double-stranded DNA molecules: a neutron scattering investigation

Abstract

. Temperature dependence of fast fluctuations in single-and double-stranded DNA molecules. A neutron scattering investigation.. Philosophical Magazine, Taylor & Francis, 2007, 87 (3-5) AbstractThrough elastic neutron scattering measurements we have investigated the picosecond dynamics of dry and hydrated powders of DNA in the double-stranded (dsDNA) and single-stranded (ssDNA) state, in the wide temperature range from 20 to 300 K. The extracted mean square displacements of DNA hydrogen atoms exhibit an onset of anharmonicity at around 100 K. The dynamics of the hydrated samples shows a further anharmonic contribution appearing at a temperature T d = 230 -240 K. Such dynamical behaviour is similar to the well-studied dynamical transition found in hydrated protein powders. The mean square displacements of dsDNA and ssDNA are practically superimposed in the whole temperature range for both dry and hydrated samples. This suggests that the DNA local mobility in the picosecond timescale does not depend on the single-or double-stranded conformation.

Coupled thermal fluctuations of proteins and protein hydration water on the picosecond timescale

“…In a number of previous works, hydrated protein powders were shown to exhibit a dynamical transition at around 200-220 K [15,17,35]. Similar values were found for hydrated DNA [18,37]. Very recently, it has been suggested that the dynamical transition of hydration water is the effect of a fragile-to-strong dynamical crossover, which is characterised by the change in the temperature dependence of quantities such as the average translational relaxation time, and corresponds to a transition in water structure from a predominantly high-density (more fluid state) to a low-density (less fluid state) form [13].…”

“…Such a coupling is quite evident even in the most intriguing phenomenon which characterises the dynamics of proteins in the picosecond timescale, the so-called "dynamical transition". This event, which consists in the activation above 200-220K of large-amplitude anharmonic protein internal motions, is well visible in hydrated biomolecules whereas it cannot be detected in dry systems [14][15][16][17][18]. It has been proposed that the protein dynamical transition does not correspond to a real "transition", but it is likely the signature of the onset of the conformational mean square displacements (MSD) [19].…”

The “Protein Dynamical Transition” Does Not Require the Protein Polypeptide Chain

“…The Journal of Physical Chemistry Letters LETTER the same temperature region has also been observed in DNA 22 and transfer RNA (tRNA), 23 suggesting that it is not a peculiar feature of peptide polymers.…”

The role of primitive relaxation in the dynamics of aqueous mixtures, nano-confined water and hydrated proteins

“…Approximately the same T D from 225 to 240 K were reported the following studies using IN13. (1) D 2 O hydrated myoglobin by Doster et al [77], (2) C-phycocyanin (C-PC) by Köper et al [107], (3) various deuterated sucrose/water and trehalose/water mixtures by Magazú et al [108], (4) hydrated single-stranded and double-stranded DNA [109], and (5) ferric horse myoglobin (met-Mb) hydrated with D 2 O at 20% level [110].…”