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

Paciaroni, Alessandro; Orecchini, A.; Cornicchi, E.; Marconi, M.; Petrillo, C.; Haertlein, Michael; Moulin, Martine; Sacchetti, F.

doi:10.1080/14786430802464263

Cited by 15 publications

(19 citation statements)

References 37 publications

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“…the anharmonic onset of molecular displacements at temperature T d ) observed by either Mo¨ssbauer spectroscopy [32,33] or by neutron scattering [34][35][36][37][38][39][40][41][42][43], and explain the dependence of dynamic transition temperature T d on the energy resolution of the spectrometer used and the solvent of the hydrated protein.…”

Section: Introductionmentioning

confidence: 98%

Resolving the ambiguity of the dynamics of water and clarifying its role in hydrated proteins

Ngai

Capaccioli

Ancherbak

et al. 2011

Philosophical Magazine

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The dynamics of water in aqueous mixtures with various hydrophilic solutes can be probed over practically unrestricted temperature and frequency ranges, in contrast to bulk water where crystallization preempts such study. The characteristics of the dynamics of water and their trends observed in aqueous mixtures on varying the solutes and concentration of water, in conjunction with that of water confined in spaces of nanometer size, lead us to infer the fundamental traits of the dynamics of water. These include the universal secondary relaxation, here called the nu-relaxation, the low degree of intermolecular coupling/cooperativity, and the 'strong' character of the structural primary relaxation. The dynamics of hydration water in hydrated proteins at sufficiently high hydration levels are similar in every respect to that in aqueous mixtures. In particular, the nu-relaxation of hydration water has a relaxation time nearly the same as that of the nu-relaxation of aqueous mixtures above and below the glass transition temperature. This can explain the dynamics transition observed by Mossbauer spectroscopy and neutron scattering. The fact that it is coupled to atomic motions of the hydrated protein, like similar situation in aqueous mixtures, explains why the dynamic transition is observed by neutron scattering at the same temperature whether the hydration water is H(2)O or D(2)O. The possibility that the nu-relaxation of the solvent is instrumental for biological function of hydrated biomolecules is suggested by the comparable temperature dependences of the ligand escape rate and the reciprocal of the nu-relaxation time

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Section: Introductionmentioning

confidence: 98%

Resolving the ambiguity of the dynamics of water and clarifying its role in hydrated proteins

Ngai

Capaccioli

Ancherbak

et al. 2011

Philosophical Magazine

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“…In fact, the very basic glass transition was observed in solvated proteins by calorimetry [7,8,9,10,11,12], thermal expansion measurements [13], and Brillouin scattering [14], with the glass transition temperature T g decreasing on increasing the hydration level and generally falls within the range of 160 K to 200 K, and can be higher if water is totally absent in the solvent such as pure glycerol or the solvent is 20 wt% of water in the disaccaride, sucrose [12,13]. Besides the relation to glass transition, another general phenomenon exhibited by solvated proteins which has occupied much attention is the so-called dynamic transition (i.e., the anharmonic onset of molecular displacements given by the mean square displacement u 2 at temperature T d ) observed for instance by either Mössbauer spectroscopy [15,16] or by neutron scattering [7,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34]. The protein dynamic transition temperature T d depends on the time scale or energy resolution of the spectrometer used.…”

Section: Introductionmentioning

confidence: 99%

Evidence of Coexistence of Change of Caged Dynamics at T_g and the Dynamic Transition at T_d in Solvated Proteins

et al. 2012

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Mössbauer spectroscopy and neutron scattering measurements on proteins embedded in solvents including water and aqueous mixtures have emphasized the observation of the distinctive temperature dependence of the atomic mean square displacements, , commonly referred to as the dynamic transition at some temperature T(d). At low temperatures, increases slowly, but it assumes stronger temperature dependence after crossing T(d), which depends on the time/frequency resolution of the spectrometer. Various authors have made connection of the dynamics of solvated proteins, including the dynamic transition to that of glass-forming substances. Notwithstanding, no connection is made to the similar change of temperature dependence of obtained by quasielastic neutron scattering when crossing the glass transition temperature T(g), generally observed in inorganic, organic, and polymeric glass-formers. Evidences are presented here to show that such a change of the temperature dependence of from neutron scattering at T(g) is present in hydrated or solvated proteins, as well as in the solvent used, unsurprisingly since the latter is just another organic glass-former. If unaware of the existence of such a crossover of at T(g), and if present, it can be mistaken as the dynamic transition at T(d) with the ill consequences of underestimating T(d) by the lower value T(g) and confusing the identification of the origin of the dynamic transition. The obtained by neutron scattering at not so low temperatures has contributions from the dissipation of molecules while caged by the anharmonic intermolecular potential at times before dissolution of cages by the onset of the Johari-Goldstein β-relaxation or of the merged α-β relaxation. The universal change of at T(g) of glass-formers, independent of the spectrometer resolution, had been rationalized by sensitivity to change in volume and entropy of the dissipation of the caged molecules and its contribution to . The same rationalization applies to hydrated and solvated proteins for the observed change of at T(g).

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“…Because such fleeting minds in nonliving matter possess no memory and no means for communication with the surrounding world, they lack many of the features that we attribute to human consciousness. In the presence of interfaces provided by lipid membranes or protein biomolecules, however, water molecules can form extended hydrogen bond networks (Paciaroni et al, 2008;Fayer, 2012;Stöhr & Tkatchenko, 2019) whose interfacial orientational relaxation timescale of 18 ps is almost an order of magnitude larger compared with the relaxation time of 2.6 ps in bulk water (Fayer, 2012). This already illustrates how the presence of biomolecules supplies a form of ultrafast memory for thin layers of interfacial water.…”

Section: Physical Properties and Theoretical Utility Of Quantum Informationmentioning

confidence: 92%

Quantum information theoretic approach to the mind–brain problem

Georgiev

2020

Progress in Biophysics and Molecular Biology

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The brain is composed of electrically excitable neuronal networks regulated by the activity of voltage-gated ion channels. Further portraying the molecular composition of the brain, however, will not reveal anything remotely reminiscent of a feeling, a sensation or a conscious experience. In classical physics, addressing the mind-brain problem is a formidable task because no physical mechanism is able to explain how the brain generates the unobservable, inner psychological world of conscious experiences and how in turn those conscious experiences steer the underlying brain processes toward desired behavior. Yet, this setback does not establish that consciousness is non-physical. Modern quantum physics affirms the interplay between two types of physical entities in Hilbert space: unobservable quantum states, which are vectors describing what exists in the physical world, and quantum observables, which are operators describing what can be observed in quantum measurements. Quantum no-go theorems further provide a framework for studying quantum brain dynamics, which has to be governed by a physically admissible Hamiltonian. Comprising consciousness of unobservable quantum information integrated in quantum brain states explains the origin of the inner privacy of conscious experiences and revisits the dynamic timescale of conscious processes to picosecond conformational transitions of neural biomolecules. The observable brain is then an objective construction created from classical bits of information, which are bound by Holevo's theorem, and obtained through the measurement of quantum brain observables. Thus, quantum information theory clarifies the distinction between the unobservable mind and the observable brain, and supports a solid physical foundation for consciousness research.

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

Cited by 15 publications

References 37 publications

Resolving the ambiguity of the dynamics of water and clarifying its role in hydrated proteins

Resolving the ambiguity of the dynamics of water and clarifying its role in hydrated proteins

Evidence of Coexistence of Change of Caged Dynamics at T_g and the Dynamic Transition at T_d in Solvated Proteins

Quantum information theoretic approach to the mind–brain problem

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

Cited by 15 publications

References 37 publications

Resolving the ambiguity of the dynamics of water and clarifying its role in hydrated proteins

Resolving the ambiguity of the dynamics of water and clarifying its role in hydrated proteins

Evidence of Coexistence of Change of Caged Dynamics at Tg and the Dynamic Transition at Td in Solvated Proteins

Quantum information theoretic approach to the mind–brain problem

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Evidence of Coexistence of Change of Caged Dynamics at T_g and the Dynamic Transition at T_d in Solvated Proteins