Molecular dynamics simulations of tubulin structure and calculations of electrostatic properties of microtubules

Tuszyski, J. A.; Brown, Janice A.; Crawford, Ellen; Carpenter, Eric J.; Nip, M. L. A.; Dixon, J.M.; Satari, M. V.

doi:10.1016/j.mcm.2005.05.002

Cited by 107 publications

(104 citation statements)

References 17 publications

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“…It was reported [23] that a large negative charge is distributed (≈20e per TB monomer) on the surface of MTs with visible asymmetry between the + and − ends. The TB's permanent dipole moment was calculated as approximately 1800 debye [24], almost perpendicular to the protofilament axis. Chiral ferroelectric features of TB dimers within polymerized MTs underlied a LQ model [18] for the non-linear dynamics of a single MT leading to the above mentioned solitonic trigger mechanism for ACC.…”

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confidence: 99%

Gravitational Symmetry Breaking Leads to a Polar Liquid Crystal Phase of Microtubules In Vitro

et al. 2005

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Abstract. Recent space-flight experiments performed by Tabony's team provided further evidence that a microgravity environment strongly affects the spatio-temporal organization of microtubule assemblies. Characteristic time and length scales were found that govern the organization of oriented bundles under Earth's gravitational field (GF). No such organization has been observed in a microgravity environment. This paper discusses physical mechanisms resulting in pattern formation under gravity and its disappearance in microgravity. The subtle interplay between chemical kinetics, diffusion, gravitational drift, thermal fluctuations, electrostatic interactions and liquid crystalline characteristics provides a plausible scenario.

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confidence: 99%

Gravitational Symmetry Breaking Leads to a Polar Liquid Crystal Phase of Microtubules In Vitro

et al. 2005

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“…Based on the crystal structure of tubulin, computer simulations and experimental tests have yielded an electric dipole moment of 1,740 Debye, a refractive index of 2.90, a high frequency dielectric constant of 8.41, and a high frequency polarizability of 2.1 × 10 −33 Cm 2 /V [24]. As well, an electrostatic potential map of the crystal structure has shown that the interior of the tubulin molecule contains a fairly symmetric double-well structure, providing a confining potential for a mobile electron (see [18] and Section 3).…”

Section: Tubulin's Biophysical Propertiesmentioning

confidence: 99%

“…Each monomer is composed of approximately 450 amino acids, or about 7000 atoms [18]. The monomer structures, composed of a double β-sheet core encircled by several α-helices, can be separated into three functional domains: the amino-terminal domain containing a nucleotide-binding region, the intermediate domain containing the taxol and colchicine drug binding sites, and the carboxy-terminal domain containing the suggested motor protein binding region [18]. Both monomers can bind a molecule of GTP, but only the β-tubulin will hydrolyze it to GDP.…”

Section: Tubulin's Biophysical Propertiesmentioning

confidence: 99%

“…MT-level classical information processing could provide an enormous increase in the brain's computing power. Considering 10 11 neurons in the brain with 10 4 synapses each switching at a rate of 10 3 Hz yields a computational power of 10 18 operations per second on average. The currently accepted scientific model suggests that cognition and higher brain function arises from this computational complexity.…”

Section: Introductionmentioning

confidence: 99%

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A critical assessment of the information processing capabilities of neuronal microtubules using coherent excitations

Craddock

Tuszyński

2009

J Biol Phys

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Evidence for signaling, communication, and conductivity in microtubules (MTs) has been shown through both direct and indirect means, and theoretical models predict their potential use in both classical and quantum information processing in neurons. The notion of quantum information processing within neurons has been implicated in the phenomena of consciousness, although controversies have arisen in regards to adverse physiological temperature effects on these capabilities. To investigate the possibility of quantum processes in relation to information processing in MTs, a biophysical MT model is used based on the electrostatic interior of the tubulin protein. The interior is taken to constitute a double-well potential structure within which a mobile electron is considered capable of occupying at least two distinct quantum states. These excitonic states together with MT lattice vibrations determine the state space of individual tubulin dimers within the MT lattice. Tubulin dimers are taken as quantum well structures containing an electron that can exist in either its ground state or first excited state. Following previous models involving the mechanisms of exciton energy propagation, we estimate the strength of exciton and phonon interactions and their effect on the formation and dynamics of coherent exciton domains within MTs. Also, estimates of energy and timescales for excitons, phonons, their interactions, and thermal effects are presented. Our conclusions cast doubt on the possibility of sufficiently long-lived coherent exciton/phonon structures existing at physiological temperatures in the absence of thermal isolation mechanisms. These results are discussed in comparison with previous models based on quantum effects in non-polar hydrophobic regions, which have yet to be disproved.

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“…Such argumentation is, however, too simplistic. Considering, for instance, a molecule with a dipole moment p = 10 −27 Cm, which is roughly the dipole moment of the tubulin protein [10], in the radiofrequency electric field of the intensity of about E = 10 6 V/m, which is realistic to expect on a nanometer scale around electrically polar vibrating molecules [11][12][13], we get interaction energy comparable to thermal energy per degree of freedom 2 , pE ≈ kT . In order to promote a deeper discussion about physical possibility of electromagnetic interactions in biosystems on radio wavelengths, we try to clarify here what structures on which spatial scale can be involved in such interactions.…”

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confidence: 96%

Radiofrequency and microwave interactions between biomolecular systems

Kučera

Cifra

2015

J Biol Phys

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The knowledge of mechanisms underlying interactions between biological systems, be they biomacromolecules or living cells, is crucial for understanding physiology, as well as for possible prevention, diagnostics and therapy of pathological states. Apart from known chemical and direct contact electrical signaling pathways, electromagnetic phenomena were proposed by some authors to mediate non-chemical interactions on both intracellular and intercellular levels. Here, we discuss perspectives in the research of nanoscale electromagnetic interactions between biosystems on radiofrequency and microwave wavelengths. Based on our analysis, the main perspectives are in (i) the micro and nanoscale characterization of both passive and active radiofrequency properties of biomacromolecules and cells, (ii) experimental determination of viscous damping of biomacromolecule structural vibrations and (iii) detailed analysis of energetic circumstances of electromagnetic interactions between oscillating polar biomacromolecules. Current cutting-edge nanotechnology and computational techniques start to enable such studies so we can expect new interesting insights into electromagnetic aspects of molecular biophysics of cell signaling.

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Molecular dynamics simulations of tubulin structure and calculations of electrostatic properties of microtubules

Cited by 107 publications

References 17 publications

Gravitational Symmetry Breaking Leads to a Polar Liquid Crystal Phase of Microtubules In Vitro

Gravitational Symmetry Breaking Leads to a Polar Liquid Crystal Phase of Microtubules In Vitro

A critical assessment of the information processing capabilities of neuronal microtubules using coherent excitations

Radiofrequency and microwave interactions between biomolecular systems

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