The origin of the dynamic transition in proteins

Khodadadi, Sheila; Pawlus, S.; Roh, Joon Ho; Sakai, Victoria García; Mamontov, Eugene; Sokolov, Alexei P.

doi:10.1063/1.2927871

Cited by 161 publications

(245 citation statements)

References 32 publications

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“…4, which we concluded must be due to the dynamics of the interfacial water since it is basically universal and present also in solid systems with only water molecules moving on the given time-scale, has also been suggested [37] to mainly arise from protein dynamics. Although fast local protein dynamics occurs on a similar time-scale as the main water process the small dielectric constant of a protein (ɛ ≈ 2-4) compared to that of water (ɛ ≈ 80 at room temperature) should ensure that the protein contribution to the dielectric relaxation process is minor compared to Fig.…”

Section: Discussionmentioning

confidence: 96%

The protein glass transition as measured by dielectric spectroscopy and differential scanning calorimetry

Jansson¹,

Swenson

2010

Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics

102

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The glass transition and its related dynamics of myoglobin in water and in a water-glycerol mixture have been investigated by dielectric spectroscopy and differential scanning calorimetry (DSC). For all samples, the DSC measurements display a glass transition that extends over a large temperature range. Both the temperature of the transition and its broadness decrease rapidly with increasing amount of solvent in the system. The dielectric measurements show several dynamical processes, due to both protein and solvent relaxations, and in the case of pure water as solvent the main protein process (which most likely is due to conformational changes of the protein structure) exhibits a dynamic glass transition (i.e. reaches a relaxation time of 100 s) at about the same temperature as the calorimetric glass transition temperature T g is found. This glass transition is most likely caused by the dynamic crossover and the associated vanishing of the α-relaxation of the main water relaxation, although it does not contribute to the calorimetric T g . This is in contrast to myoglobin in water-glycerol, where the main solvent relaxation makes the strongest contribution to the calorimetric glass transition. For all samples it is clear that several proteins processes are involved in the calorimetric glass transition and the broadness of the transition depends on how much these different relaxations are separated in time.

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Section: Discussionmentioning

confidence: 96%

The protein glass transition as measured by dielectric spectroscopy and differential scanning calorimetry

Jansson¹,

Swenson

2010

Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics

102

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“…For example, it has been reported that the transition is coupled to the onset of translational motions in hydration water [47][48][49]. In addition, it has been debated whether the transition is a real phenomenon, or merely a manifestation of the fact that the measurable atomic dynamics enter the experimentally accessible resolution window above certain temperatures [17,18,24,25,27]. In such a scenario, the dynamic motions of the biomolecules may increase without any discontinuity.…”

Section: Resultsmentioning

confidence: 99%

Mean-squared atomic displacements in hydrated lysozyme, native and denatured

2010

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We use elastic neutron scattering to demonstrate that a sharp increase in the mean-squared atomic displacements, commonly observed in hydrated proteins above 200 K and often referred to as the dynamical transition, is present in the hydrated state of both native and denatured lysozyme. A direct comparison of the native and denatured protein thus confirms that the presence of the transition in the mean-squared atomic displacements is not specific to biologically functional molecules.

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“…Since secondary β-relaxation processes exist also in the bulk solvent, the fluctuations localized in the hydration shell of the protein are classified as β h -relaxation and are expected to carry the dynamics distinct from the bulk [25]. The dynamical transition then occurs when the β hrelaxation of the hydration shell slows sufficiently down, with lowering temperature, to become longer than the instrumental time-scale (dynamical freezing) [26,27].…”

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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The origin of the dynamic transition in proteins

Cited by 161 publications

References 32 publications

The protein glass transition as measured by dielectric spectroscopy and differential scanning calorimetry

The protein glass transition as measured by dielectric spectroscopy and differential scanning calorimetry

Mean-squared atomic displacements in hydrated lysozyme, native and denatured

Dynamical and orientational structural crossovers in low-temperature glycerol

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