Three Classes of Motion in the Dynamic Neutron-Scattering Susceptibility of a Globular Protein

Hong, Liang; Smolin, Nikolai; Lindner, Benjamin; Sokolov, Alexei P.; Smith, Jeremy C.

doi:10.1103/physrevlett.107.148102

Cited by 81 publications

(150 citation statements)

References 25 publications

(72 reference statements)

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“…The Nyquist theorem was found to be violated for a number of glassforming materials, where a kink in the MSD vs. temperature is often observed at the laboratory glass transition [6]. More complex behavior, with several kinks [7][8][9], was observed for proteins in partially hydrated powders or in the polycrystalline form [10,11].…”

Section: Introductionmentioning

confidence: 99%

Dynamical and orientational structural crossovers in low-temperature glycerol

2016

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Mean square displacements of hydrogen atoms in glass-forming materials and proteins, as reported by incoherent elastic neutron scattering, show kinks in their temperature dependence. This crossover, known as the dynamical transition, connects two approximately linear regimes. It is often assigned to the dynamical freezing of subsets of molecular modes at the point of equality between their corresponding relaxation times and the instrumental observation window. The origin of the dynamical transition in glass-forming glycerol is studied here by extensive molecular dynamics simulations. We find the dynamical transition to occur for both the center of mass translations and the molecular rotations at the same temperature, insensitive to changes of the observation window. Both the translational and rotational dynamics of glycerol show a dynamic crossover from the structural to a secondary relaxation at the temperature of the dynamical transition. A significant and discontinuous increase in the orientational Kirkwood factor and in the dielectric constant is observed in the same range of temperatures. We, however, do not find any indications of a true thermodynamic transition to an ordered low-temperature phase. We therefore suggest that all observed crossovers are dynamic in character. The increase in the dielectric constant is related to the dynamic freezing of dipolar domains on the time-scale of simulations.

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Section: Introductionmentioning

confidence: 99%

Dynamical and orientational structural crossovers in low-temperature glycerol

2016

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“…Recent simulations of hydrated lysozyme showed accordingly that whereas hydration water has diffusive-like translational motion, proteins exhibit only localized atomic fluctuations on the pico-to nano-second time scale. 69 The same conclusions were drawn from a neutron scattering study of D 2 O hydrated hydrogenated GFP (green fluorescent protein) and a H 2 O hydrated sample of fully deuterated GFP. 9 The values obtained for the proton mobility as a function of temperature for the two hydrated samples ( Fig.…”

Section: Discussionmentioning

confidence: 65%

Hydration water and peptide dynamics – two sides of a coin. A neutron scattering and adiabatic calorimetry study at low hydration and cryogenic temperatures

Bastos

Alves

Maia

et al. 2013

Phys. Chem. Chem. Phys.

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In the present work we bridge neutron scattering and calorimetry in the study of a low-hydration sample of a 15-residue hybrid peptide from cecropin and mellitin CA(1-7)M(2-9) of proven antimicrobial activity.Quasielastic and low-frequency inelastic neutron spectra were measured at defined hydration levelsa nominally 'dry' sample (specific residual hydration h = 0.060 g/g), a H 2 O-hydrated (h = 0.49) and a D 2 Ohydrated one (h = 0.51). Averaged mean square proton mobilities were derived over a large temperature range (50-300 K) and the vibrational density of states (VDOS) were evaluated for the hydrated samples. The heat capacity of the H 2 O-hydrated CA(1-7)M(2-9) peptide was measured by adiabatic calorimetry in the temperature range 5-300 K, for different hydration levels. The glass transition and water crystallization temperatures were derived in each case. The existence of different types of water was inferred and their amounts calculated. The heat capacities as obtained from direct calorimetric measurements were compared to the values derived from the neutron spectroscopy by way of integrating appropriately normalized VDOS functions. While there is remarkable agreement with respect to both temperature dependence and glass transition temperatures, the results also show that the VDOS derived part represents only a fraction of the total heat capacity obtained from calorimetry. Finally our results indicate that both hydration water and the peptide are involved in the experimentally observed transitions.

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“…The intrinsic T D is defined as the temperature at which the intrinsic r 2 shows a marked increase with increasing temperature. There can be more than one T D [13,15].…”

Section: Introductionmentioning

confidence: 99%

“…As temperature is increased the MSD increases and often goes through a marked increase at a specific temperature or temperatures, T D , denoted the dynamical transition. [1][2][3][12][13][14][15][16] The onset of large values of MSD are associated with the onset of function in proteins. [3,[17][18][19][20][21][22] Essentially, the large amplitude MSD enables contact between different parts of the protein which promotes chemical activity, function and possible folding.…”

Section: Introductionmentioning

confidence: 99%

Intrinsic mean-square displacements in proteins

Vural

Glyde

2012

Phys. Rev. E

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The thermal mean square displacement (MSD) of hydrogen in proteins and its associated hydration water is measured by neutron scattering experiments and used an indicator of protein function. The observed MSD as currently determined depends on the energy resolution width of the neutron scattering instrument employed. We propose a method for obtaining the intrinsic MSD of H in the proteins, one that is independent of the instrument resolution width. The intrinsic MSD is defined as the infinite time value of r 2 that appears in the Debye-Waller factor. The method consists of fitting a model to the resolution broadened elastic incoherent structure factor or to the resolution dependent MSD. The model contains the intrinsic MSD, the instrument resolution width and a rate constant characterizing the motions of H in the protein. The method is illustrated by obtaining the intrinsic MSD r 2 of heparan sulphate (HS-0.4), Ribonuclease A and Staphysloccal Nuclase (SNase) from data in the literature.

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Three Classes of Motion in the Dynamic Neutron-Scattering Susceptibility of a Globular Protein

Cited by 81 publications

References 25 publications

Dynamical and orientational structural crossovers in low-temperature glycerol

Dynamical and orientational structural crossovers in low-temperature glycerol

Hydration water and peptide dynamics – two sides of a coin. A neutron scattering and adiabatic calorimetry study at low hydration and cryogenic temperatures

Intrinsic mean-square displacements in proteins

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