Electromagnetic-field effects on structure and dynamics of amyloidogenic peptides

Quest for New Generation Biocompatible Materials: Tailoring β-Peptide Structure and Interactions via Synergy of Experiments and Modelling

Peptide-based self-assembly has been used to produce a wide range of nanostructures. While most of these systems involve self-assembly of α-peptides, more recently β-peptides have also been shown to undergo supramolecular self-assembly, and have been used to produce materials for applications in tissue engineering, cell culture and drug delivery. In order to engineer new materials with specific structure and function, theoretical molecular modelling can provide significant insights into the collective balance of non-covalent interactions that drive the self-assembly and determine the structure of the resultant supramolecular materials under different conditions. However, this approach has only recently become feasible for peptide-based self-assembled nanomaterials, particularly those that incorporate non α-amino acids. This perspective provides an overview of the challenges associated with computational modelling of the self-assembly of β-peptides and the recent success using a combination of experimental and computational techniques to provide insights into the self-assembly mechanisms and fully atomistic models of these new biocompatible materials.

Disrupting Dimeric β-Amyloid by Electric Fields

The early oligomers of the amyloid Aβ peptide are implicated in Alzheimer's disease, but their transient nature complicates the characterization of their structure and toxicity. Here, we investigate the stability of the minimal toxic species, i.e., β-amyloid dimers, in the presence of an oscillating electric field. We first use deep learning (AlphaFold-multimer) for generating initial models of Aβ42 dimers. The flexibility and secondary structure content of the models are then analyzed by multiple runs of molecular dynamics (MD). Structurally stable models are similar to ensemble representatives from microsecond-long MD sampling. Finally, we employ the validated model as the starting structure of MD simulations in the presence of an external oscillating electric field and observe a fast decay of β-sheet content at high field strengths. Control simulations using the helical dimer of the 42-residue leucine zipper peptide show higher structural stability than the Aβ42 dimer. The simulation results provide evidence that an external electric field (oscillating at 1 GHz) can disrupt amyloid oligomers which should be further investigated by experiments with brain organoids in vitro and eventually in vivo.

Preventing the amyloid-beta peptides accumulation on the cell membrane by applying GHz electric fields: A molecular dynamic simulation

Alzheimer's disease is associated with accumulating different amyloid peptides on the nerve cell membranes. The non-thermal effects of the GHz electric fields in this topic have yet to be well recognized. Hence, in this study, the impacts of 1 and 5 GHz electric fields on the amyloid peptide proteins accumulation on the cell membrane have been investigated, utilizing molecular dynamics (MD) simulation. The obtained results indicated that this range of electric fields did not significantly affect the peptide structure. Moreover, it was found that the peptide penetration into the membrane was increased as the field frequency was increased when the system was exposed to a 20 mv/nm oscillating electric field. In addition, it was observed that the protein-membrane interaction is reduced significantly in the presence of the 70 mv/nm electric field. The molecular level results reported in this study could be helpful in better understanding Alzheimer's disease.

Exposure to the electric field: A potential way to block the aggregation of histidine tautomeric isomers of β-amyloid

Controlling protein misfolding and accumulation in neurodegeneration is a challenge in chemical neuroscience. The application of appropriate electric fields (EFs) can be a potential noninvasive therapy to treat neuro disorders. The effect of EFs of varying intensities and directions on the conformational dynamics of β-Amyloid40 (Aβ40) under histidine tautomerism has been investigated for the first time. Our findings suggest that peptides tend to align their dipole moments with the orientation of EF. Irrespective of the EF direction, the dipole moment magnitude is affected by the EF strength. With the conformational changes, the EF strength equal to 0.5 V/nm destroyed the β-sheet content of the δδδ isomer as a potentially toxic agent. The content of the alpha-helical structure which can be transformed into the β-sheet is reduced. The strength of the EF showed a significant influence on the reduction of the number of intra-protein hydrogen bonds especially when EF is equal to 0.5 V/nm which could facilitate destabilization of the structure of the peptides. Current findings provide quantitative insights into the tautomerization-mediated Aβ40 dynamic and conformational changes induced by the external EFs in aqueous solutions, which may provide beneficial information for use as a therapeutic technique.

Capturing the Polarization Response of Solvated Proteins under Constant Electric Fields in Molecular Dynamics Simulations

We capture and compare the polarization response of a solvated globular protein ubiquitin to static electric (E-fields) using atomistic molecular dynamics simulations. We collectively follow E-field induced changes, electrical and structural, occurring across multiple trajectories using the magnitude of the protein dipole vector (P_p ). E-fields antiparallel to P_p induce faster structural changes and more facile protein unfolding relative to parallel fields of the same strength. While weak E-fields (0.1-0.5 V/nm) do not unfold ubiquitin and produce a reversible polarization, strong E-fields (1-2 V/nm) unfold the protein through a pathway wherein the helix:β-strand interactions rupture before those for the β1-β5 clamp. Independent of E-field direction, high E-field induced structural changes are also reversible if the field is switched off before P_p exceeds 2 times its equilibrium value. We critically examine the dependence of water properties, protein rotational diffusion and E-field induced protein unfolding pathways on the thermostat/barostat parameters used in our simulations.

Transcranial Electromagnetic Treatment Stops Alzheimer’s Disease Cognitive Decline over a 2½-Year Period: A Pilot Study

Background: There is currently no therapeutic that can stop or reverse the progressive memory impairment of Alzheimer’s disease (AD). However, we recently published that 2 months of daily, in-home transcranial electromagnetic treatment (TEMT) reversed the cognitive impairment in eight mild/moderate AD subjects. These cognitive enhancements were accompanied by predicted changes in AD markers within both the blood and cerebrospinal fluid (CSF). Methods: In view of these encouraging findings, the initial clinical study was extended twice to encompass a period of 2½ years. The present study reports on the resulting long-term safety, cognitive assessments, and AD marker evaluations from the five subjects who received long-term treatment. Results: TEMT administration was completely safe over the 2½-year period, with no deleterious side effects. In six cognitive/functional tasks (including the ADAS-cog13, Rey AVLT, MMSE, and ADL), no decline in any measure occurred over this 2½-year period. Long-term TEMT induced reductions in the CSF levels of C-reactive protein, p-tau217, Aβ1-40, and Aβ1-42 while modulating CSF oligomeric Aβ levels. In the plasma, long-term TEMT modulated/rebalanced levels of both p-tau217 and total tau. Conclusions: Although only a limited number of AD patients were involved in this study, the results suggest that TEMT can stop the cognitive decline of AD over a period of at least 2½ years and can do so with no safety issues.

Long-Term Wi-Fi Exposure From Pre-Pubertal to Adult Age on the Spermatogonia Proliferation and Protective Effects of Edible Bird’s Nest Supplementation

Children are vulnerable to the radiofrequency radiation (RFR) emitted by Wi-Fi devices. Nevertheless, the severity of the Wi-Fi effect on their reproductive development has been sparsely available. Therefore, this study was conducted to evaluate the Wi-Fi exposure on spermatogonia proliferation in the testis. This study also incorporated an approach to attenuate the effect of Wi-Fi by giving concurrent edible bird’s nest (EBN) supplementation. It was predicted that Wi-Fi exposure reduces spermatogonia proliferation while EBN supplementation protects against it. A total of 30 (N = 30) 3-week-old Sprague Dawley weanlings were divided equally into five groups; Control, Control EBN, Wi-Fi, Sham Wi-Fi, and Wi-Fi + EBN. 2.45 GHz Wi-Fi exposure and 250 mg/kg EBN supplementation were conducted for 14 weeks. Findings showed that the Wi-Fi group had decreased in spermatogonia mitosis status. However, the mRNA and protein expression of c-Kit-SCF showed no significant decrease. Instead, the reproductive hormone showed a reduction in FSH and LH serum levels. Of these, LH serum level was decreased significantly in the Wi-Fi group. Otherwise, supplementing the Wi-Fi + EBN group with 250 mg/kg EBN resulted in a significant increase in spermatogonia mitotic status. Even though EBN supplementation improved c-Kit-SCF mRNA and protein expression, the effects were insignificant. The improvement of spermatogonia mitosis appeared to be associated with a significant increase in blood FSH levels following EBN supplementation. In conclusion, the long-term Wi-Fi exposure from pre-pubertal to adult age reduces spermatogonia proliferation in the testis. On the other hand, EBN supplementation protects spermatogonia proliferation against Wi-Fi exposure.

Environmental Exploration of Ultra-Dense Nanobubbles: Rethinking Sustainability

Nanobubbles are nanoscopic gaseous domains than can exist on solid surfaces or in bulk liquids. They have attracted significant attention in the last decade due to their long-time (meta)stability and ready potential for real-world applications, especially in environmental engineering and more sustainable ecosystems, water treatment, irrigation, and crop growth. After reviewing important nano-bubble science and activity, with some of the latest promising results in agriculture, we point out important directions in applications of nano-bubble phenomena for boosting sustainability, with viewpoints on how to revolutionise best-practice environmental and green sustainability, taking into account economic drivers and impacts. More specifically, it is pointed out how nanobubbles may be used as delivery vehicles, or “nano-carriers”, for nutrients or other agents to specific targets in a variety of ecosystems of environmental relevance, and how core this is to realising a vision of ultra-dense NBs in shaping a positive and lasting impact on ecosystems and our natural environment.

Electromagnetic bioeffects: a multiscale molecular simulation perspective

Electromagnetic bioeffects remain an enigma from both the experimental and theoretical perspectives despite the ubiquitous presence of related technologies in contemporary life. Multiscale computational modelling can provide valuable insights into biochemical systems and predict how they will be perturbed by external stimuli. At a microscopic level, it can be used to determine what (sub)molecular scale reactions various stimuli might induce; at a macroscopic level, it can be used to examine how these changes affect dynamic behaviour of essential molecules within the crowded biomolecular milieu in living tissues. In this review, we summarise and evaluate recent computational studies that examined the impact of externally applied electric and electromagnetic fields on biologically relevant molecular systems. First, we briefly outline the various methodological approaches that have been employed to study static and oscillating field effects across different time and length scales. The practical value of such modelling is then illustrated through representative case-studies that showcase the diverse effects of electric and electromagnetic field on the main physiological solvent - water, and the essential biomolecules - DNA, proteins, lipids, as well as some novel biomedically relevant nanomaterials. The implications and relevance of the theoretical multiscale modelling to practical applications in therapeutic medicine are also discussed. Finally, we summarise ongoing challenges and potential opportunities for theoretical modelling to advance the current understanding of electromagnetic bioeffects for their modulation and/or beneficial exploitation in biomedicine and industry.

Electric-field induced modulation of amorphous protein aggregates: polarization, deformation, and reorientation

Proteins in their native state are only marginally stable and tend to aggregate. However, protein misfolding and condensation are often associated with undesired processes, such as pathogenesis, or unwanted properties, such as reduced biological activity, immunogenicity, or uncontrolled materials properties. Therefore, controlling protein aggregation is very important, but still a major challenge in various fields, including medicine, pharmacology, food processing, and materials science. Here, flexible, amorphous, micron-sized protein aggregates composed of lysozyme molecules reduced by dithiothreitol are used as a model system. The preformed amorphous protein aggregates are exposed to a weak alternating current electric field. Their field response is followed in situ by time-resolved polarized optical microscopy, revealing field-induced deformation, reorientation and enhanced polarization as well as the disintegration of large clusters of aggregates. Small-angle dynamic light scattering was applied to probe the collective microscopic dynamics of amorphous aggregate suspensions. Field-enhanced local oscillations of the intensity auto-correlation function are observed and related to two distinguishable elastic moduli. Our results validate the prospects of electric fields for controlling protein aggregation processes.

Effects of Externally Applied Electric Fields on the Manipulation of Solvated-Chignolin Folding: Static- versus Alternating-Field Dichotomy at Play

The interaction between a protein and external electric field (EF) can alter its structure and dynamical behavior, which has a potential impact on the biological function of proteins and cause uncertain health consequences. Conversely, the application of EFs of judiciously selected intensity and frequency can help to treat disease, and optimization of this requires a greater understanding of EF-induced effects underpinning basic protein biophysics. In the present study, chignolin─an artificial protein sufficiently small to undergo fast-folding events and transitions─was selected as an ideal prototype to investigate how, and to what extent, externally applied electric fields may manipulate or influence protein-folding phenomena. Nonequilibrium molecular dynamics (NEMD) simulations have been performed of solvated chignolin to determine the distribution of folding states and their underlying transition dynamics, in the absence and presence of externally applied electric fields (both static and alternating); a key focus has been to ascertain how folding pathways are altered in an athermal sense by external fields. Compared to zero-field conditions, a dramatically different─indeed, bifurcated─behavior of chignolin-folding processes emerges between static- and alternating-field scenarios, especially vis-à-vis incipient stages of hydrophobic-core formation: in alternating fields, fold-state populations diversified, with an attendant acceleration of state-hopping folding kinetics, featuring the concomitant emergence of a new, quasi-stable structure compared to the native structure, in field-shifted energy landscapes.

First Identification of the Effects of Low Frequency Electromagnetic Field on the Micromolecular Changes in Adipose Tissue-Derived Mesenchymal Stem Cells by Fourier Transform Infrared Spectroscopy

Purpose:

In this study, we hypothesize that exposure of adipose tissue-mesenchymal stem cells (AT-MSCs) to electromagnetic field (EMF) may impact adipose stem cells' micromolecular structure (analyzed using Fourier transform infrared spectroscopy [FTIR]).

Materials and Methods:

The AT-MSCs were exposed to continuous vertically applied sinusoidal EMF with a frequency of 50 Hz and a flux density of 1.5 mT for 24, 48, and 72 h. After an appropriate time (24, 48, 72 h) cells were washed with PBS, scrubbed, and immediately taken into FTIR analyses.

Results:

EMFs affect AT-MSCs. The greatest differences were in the range of nucleic acids and proteins in the fingerprint region which occurred after 24 and 48 h of EMF exposure. However, in the case of 72 h of EMF exposure, no significant differences were noticed in the FTIR spectra towards the control.

Conclusions:

FTIR spectra show differences between samples under the influence of EMF before they will be manifested at the morphological level. The largest differences in the range of nucleic acids and proteins in the fingerprint region occurred at 24 and 48 h of EMF exposure. That means it was during the first 48 h after EMF exposure a great number of dynamic changes occurred. However, in the case of AT-MSCs in 72 h EMF and 72 h control, no significant differences were noted in the FTIR spectra, which means that the chemical composition in these two cases is similar. EMF is not neutral for stem cells, especially in the in the first hours of interaction (24 h, 48 h).

Molecular dynamics evidence for nonthermal effects of electric fields on pectin methylesterase activity

Experimental studies relevant to the nonthermal effects of electric fields on biological systems are emerging. However, these effects are poorly understood at the molecular level. The present study investigates pectin methylesterase, a cell wall modifying enzyme in plants, exposed to various electric field strengths. Molecular dynamics (MD) of the enzyme were studied with and without (thermal-only) electric field applications. The measurements were interpreted on the basis of equivalent energy input to gain insights into the effect of electric field treatment time at a constant temperature (50 °C). Results reveal that electric fields exert nonthermal effects on both local and global protein structure. In 1 μs simulations, the results show significant (P ≤ 0.05) shrinkage of the catalytic domain and shortening of enzyme-water hydrogen bond lifetime by a 50 V cm-1 electric field. Unwinding of the helical segments, altered intra- and intermolecular hydrogen bond patterns, and increased hydration are also caused by the 50 V cm-1 electric field. This study serves to understand the electric field influence on the functional role of proteins.

Electro-opening of a microtubule lattice in silico

Modulation of the structure and function of biomaterials is essential for advancing bio-nanotechnology and biomedicine. Microtubules (MTs) are self-assembled protein polymers that are essential for fundamental cellular processes and key model compounds for the design of active bio-nanomaterials. In this in silico study, a 0.5 μs-long all-atom molecular dynamics simulation of a complete MT with approximately 1.2 million atoms in the system indicated that a nanosecond-scale intense electric field can induce the longitudinal opening of the cylindrical shell of the MT lattice, modifying the structure of the MT. This effect is field-strength- and temperature-dependent and occurs on the cathode side. A model was formulated to explain the opening on the cathode side, which resulted from an electric-field-induced imbalance between electric torque on tubulin dipoles and cohesive forces between tubulin heterodimers. Our results open new avenues for electromagnetic modulation of biological and artificial materials through action on noncovalent molecular interactions.

Amyloid Oligomers: A Joint Experimental/Computational Perspective on Alzheimer's Disease, Parkinson's Disease, Type II Diabetes, and Amyotrophic Lateral Sclerosis

Protein misfolding and aggregation is observed in many amyloidogenic diseases affecting either the central nervous system or a variety of peripheral tissues. Structural and dynamic characterization of all species along the pathways from monomers to fibrils is challenging by experimental and computational means because they involve intrinsically disordered proteins in most diseases. Yet understanding how amyloid species become toxic is the challenge in developing a treatment for these diseases. Here we review what computer, in vitro, in vivo, and pharmacological experiments tell us about the accumulation and deposition of the oligomers of the (Aβ, tau), α-synuclein, IAPP, and superoxide dismutase 1 proteins, which have been the mainstream concept underlying Alzheimer's disease (AD), Parkinson's disease (PD), type II diabetes (T2D), and amyotrophic lateral sclerosis (ALS) research, respectively, for many years.

Translocation of silica nanospheres through giant unilamellar vesicles (GUVs) induced by a high frequency electromagnetic field

Membrane model systems capable of mimicking live cell membranes were used for the first time in studying the effects arising from electromagnetic fields (EMFs) of 18 GHz where membrane permeability was observed following exposure.

A Clinical Trial of Transcranial Electromagnetic Treatment in Alzheimer's Disease: Cognitive Enhancement and Associated Changes in Cerebrospinal Fluid, Blood, and Brain Imaging

Background:

Small aggregates (oligomers) of the toxic proteins amyloid-β (Aβ) and phospho-tau (p-tau) are essential contributors to Alzheimer’s disease (AD). In mouse models for AD or human AD brain extracts, Transcranial Electromagnetic Treatment (TEMT) disaggregates both Aβ and p-tau oligomers, and induces brain mitochondrial enhancement. These apparent “disease-modifying” actions of TEMT both prevent and reverse memory impairment in AD transgenic mice.

Objective:

To evaluate the safety and initial clinical efficacy of TEMT against AD, a comprehensive open-label clinical trial was performed.

Methods:

Eight mild/moderate AD patients were treated with TEMT in-home by their caregivers for 2 months utilizing a unique head device. TEMT was given for two 1-hour periods each day, with subjects primarily evaluated at baseline, end-of-treatment, and 2 weeks following treatment completion.

Results:

No deleterious behavioral effects, discomfort, or physiologic changes resulted from 2 months of TEMT, as well as no evidence of tumor or microhemorrhage induction. TEMT induced clinically important and statistically significant improvements in ADAS-cog, as well as in the Rey AVLT. TEMT also produced increases in cerebrospinal fluid (CSF) levels of soluble Aβ_1-40 and Aβ_1-42, cognition-related changes in CSF oligomeric Aβ, a decreased CSF p-tau/Aβ_1-42 ratio, and reduced levels of oligomeric Aβ in plasma. Pre- versus post-treatment FDG-PET brain scans revealed stable cerebral glucose utilization, with several subjects exhibiting enhanced glucose utilization. Evaluation of diffusion tensor imaging (fractional anisotropy) scans in individual subjects provided support for TEMT-induced increases in functional connectivity within the cognitively-important cingulate cortex/cingulum.

Conclusion:

TEMT administration to AD subjects appears to be safe, while providing cognitive enhancement, changes to CSF/blood AD markers, and evidence of stable/enhanced brain connectivity.

Low frequency vortex magnetic field reduces amyloid β aggregation, increase cell viability and protect from amyloid β toxicity

Plaques formed by abnormal accumulation of amyloid β-peptide (Aβ) lead to onset of Alzheimer's disease (AD). Pharmacological treatments do not reduce Aβ aggregation neither restore learning and memory. Noninvasive techniques have emerged as an alternative to treat AD, such as stimulation with electromagnetic fields (EMF) that decrease Aβ deposition and reverses cognitive impairment in AD mice, even though some studies showed side effects on parallel magnetic fields stimulation. As a new approach of magnetic field (MF) stimulation, vortex magnetic fields (VMF) have been tested inducing a random movement of charged biomolecules in cells, promoting cell viability and apparently safer than parallel magnetic fields. In this study we demonstrate the effect of VMF on Aβ aggregation. The experimental strategy includes, i) design and construction of a coil capable to induce VMF, ii) evaluation of VMF stimulation on Aβ peptide induced-fibrils-formation, iii) evaluation of VMF stimulation on SH-SY5Y neuroblastoma cell line in the presence of Aβ peptide. We demonstrated for the first time that Aβ aggregation exposed to VMF during 24 h decreased ~ 86% of Aβ fibril formation compared to control. Likewise, VMF stimulation reduced Aβ fibrils-cytotoxicity and increase SH-SY5Y cell viability. These data establish the basis for future investigation that involve VMF as inhibitor of Aβ-pathology and indicate the therapeutic potential of VMF for AD treatment.

Could Microwave Irradiation Cause Misfolding of Peptides?

Microwaves have been experimentally shown to affect the folding dynamics of peptides and proteins. Using molecular dynamics, we performed all-atom simulations of a model β-peptide in aqueous solution where individual degrees of freedom of solvent molecules were decoupled to allow for investigation at non-equilibrium microwave-irradiated conditions. An elevated rotational temperature of the water medium was found to significantly affect the conformation of the peptide due to the weakened hydrogen-bonding interactions with the surrounding solvent molecules. Cluster analysis revealed that microwave irradiation can indeed act as a promoter in the formation of new misfolded peptide structures of the hairpin type, which are generally associated with the onset of several neurodegenerative disorders such as Alzheimer’s, Parkinson’s, Huntington’s, and Creutzfeldt–Jakob diseases as well as certain cancer types such as amyloidosis.

Molecular dynamics simulation of the nanosecond pulsed electric field effect on kinesin nanomotor

Kinesin is a biological molecular nanomotor which converts chemical energy into mechanical work. To fulfill various nanotechnological tasks in engineered environments, the function of biological molecular motors can be altered by artificial chemical modifications. The drawback of this approach is the necessity of designing and creating a new motor construct for every new task. We propose that intense nanosecond-scale pulsed electric field could modify the function of nanomotors. To explore this hypothesis, we performed molecular dynamics simulation of a kinesin motor domain docked on a subunit of its microtubule track - a single tubulin heterodimer. In the simulation, we exposed the kinesin motor domain to intense (100 MV/m) electric field up to 30 ns. We found that both the magnitude and angle of the kinesin dipole moment are affected. Furthermore, we found that the electric field affects contact surface area between kinesin and tubulin, the structure and dynamics of the functionally important kinesin segments, including microtubule binding motifs as well as nucleotide hydrolysis site which power the nanomotor. These findings indicate that external intense nanosecond-scale electric field could alter kinesin behavior. Our results contribute to developing novel electromagnetic methods for modulating the function of biomolecular matter at the nanoscale.

Tubulin response to intense nanosecond-scale electric field in molecular dynamics simulation

Intense pulsed electric fields are known to act at the cell membrane level and are already being exploited in biomedical and biotechnological applications. However, it is not clear if electric pulses within biomedically-attainable parameters could directly influence intra-cellular components such as cytoskeletal proteins. If so, a molecular mechanism of action could be uncovered for therapeutic applications of such electric fields. To help clarify this question, we first identified that a tubulin heterodimer is a natural biological target for intense electric fields due to its exceptional electric properties and crucial roles played in cell division. Using molecular dynamics simulations, we then demonstrated that an intense - yet experimentally attainable - electric field of nanosecond duration can affect the bβ-tubulin’s C-terminus conformations and also influence local electrostatic properties at the GTPase as well as the binding sites of major tubulin drugs site. Our results suggest that intense nanosecond electric pulses could be used for physical modulation of microtubule dynamics. Since a nanosecond pulsed electric field can penetrate the tissues and cellular membranes due to its broadband spectrum, our results are also potentially significant for the development of new therapeutic protocols.

Electric Field Disruption of Amyloid Aggregation: Potential Noninvasive Therapy for Alzheimer's Disease

The aggregation of β-amyloid peptides is a key event in the formative stages of Alzheimer's disease. Promoting folding and inhibiting aggregation was reported as an effective strategy in reducing Aβ-elicited toxicity. This study experimentally investigates the influence of the external electric field (EF) and magnetic field (MF) of varying strengths on the in vitro fibrillogenesis of hydrophobic core sequence, Aβ_16-22, and its parent peptide, Aβ_1-42. Biophysical methods such as ThT fluorescence, static light scattering, circular dichroism, and infrared spectroscopy suggest that EF has a stabilizing effect on the secondary structure, initiating a conformational switch of Aβ_16-22 and Aβ_1-42 from β to non-β conformation. This observation was further corroborated by dynamic light scattering and transmission electron microscopic studies. To mimic in vivo conditions, we repeated ThT fluorescence assay with Aβ_1-42 in human cerebrospinal fluid to verify EF-mediated modulation. The self-seeding of Aβ_1-42 and cross-seeding with Aβ_1-40 to verify that the autocatalytic amplification of self-assembly as a result of secondary nucleation also yields comparable results in EF-exposed and unexposed samples. Aβ-elicited toxicity of EF-treated samples in two neuroblastoma cell lines (SH-SY5Y and IMR-32) and human embryonic kidney cell line (HEK293) were found to be 15-38% less toxic than the EF untreated ones under identical conditions. Experiments with fluorescent labeled Aβ_1-42 to correlate reduced cytotoxicity and cell internalization suggest a comparatively smaller uptake of the EF-treated peptides. Our results provide a scientific roadmap for future noninvasive, therapeutic solutions for the treatment of Alzheimer's disease.

Human aquaporin 4 gating dynamics under axially oriented electric-field impulses: A non-equilibrium molecular-dynamics study

Human aquaporin 4 has been studied using non-equilibrium molecular dynamics simulations in the absence and presence of pulses of external electric fields. The pulses were 100 ns in duration and 0.005-0.015 V/Å in intensity acting along the pores' axes. Water diffusivity and the dipolar response of various residues of interest within the pores have been studied. Results show relatively little change in levels of water permeability per se within aquaporin channels during axially oriented field impulses, although care must be taken with regard to statistical certainty. However, the spatial variation of water permeability vis-à-vis electric-field intensity within the milieu of the channels, as revealed by heterogeneity in diffusivity-map gradients, indicates the possibility of somewhat enhanced diffusivity, owing to several residues being affected substantially by external fields, particularly for HIS 201 and 95 and ILE 93. This has the effect of increasing slightly intra-pore water diffusivity in the "pore-mouths" locale, albeit rendering it more spatially uniform overall vis-à-vis zero-field conditions (via manipulation of the selectivity filter).

The Enigma of Amyloid Forming Proteins: Insights From Molecular Simulations

Molecular level insight into the interplay between protein sequence, structure, and conformational dynamics is crucial for the comprehensive understanding of protein folding, misfolding, and aggregation phenomena that are pertinent to the formation of amyloid fibrils implicated in several degenerative diseases. Computational modelling provides insight into protein behaviour at spatial and temporal resolution still largely outside the reach of experiments. Herein we present an account of our theoretical modelling research conducted in collaboration with several experimental groups where we explored the effects of local environment on the structure and aggregation propensity of several types of amyloidogenic peptides and proteins, including apolipoprotein C-II, insulin, amylin, and amyloid-β using a variety of computational approaches.

Electropumping of Water Through Human Aquaporin 4 by Circularly Polarized Electric Fields: Dramatic Enhancement and Control Revealed by Non-Equilibrium Molecular Dynamics

An extensive suite of nonequilibrium molecular-dynamics (NEMD) simulations have been performed for ∼60 ns of human aquaporin 4 in externally applied circularly polarized (CP) electric fields, applied axially along channels. These external fields were 0.05 V/Å in intensity and 100 GHz in frequency. This has the effect of "electro-pumping" the water through the pores as prototypical biochannels, from conversion of molecules' spin angular momentum to linear momentum in the asymmetric heterogeneous-frictional environment of the pores, thus inducing overall net flow. Water's osmotic permeability was enhanced very substantially (doubled) vis-à-vis the zero-field case. This raises the tantalizing possibility of CP-field-mediated control of water permeability in aquaporins, or other biological (or biomimetic) channels as a potential viable and competitive water-treatment technology.

Investigating Ebola virus pathogenicity using molecular dynamics

BACKGROUND

Ebolaviruses have been known to cause deadly disease in humans for 40 years and have recently been demonstrated in West Africa to be able to cause large outbreaks. Four Ebolavirus species cause severe disease associated with high mortality in humans. Reston viruses are the only Ebolaviruses that do not cause disease in humans. Conserved amino acid changes in the Reston virus protein VP24 compared to VP24 of other Ebolaviruses have been suggested to alter VP24 binding to host cell karyopherins resulting in impaired inhibition of interferon signalling, which may explain the difference in human pathogenicity. Here we used protein structural analysis and molecular dynamics to further elucidate the interaction between VP24 and KPNA5.

RESULTS

As a control experiment, we compared the interaction of wild-type and R137A-mutant (known to affect KPNA5 binding) Ebola virus VP24 with KPNA5. Results confirmed that the R137A mutation weakens direct VP24-KPNA5 binding and enables water molecules to penetrate at the interface. Similarly, Reston virus VP24 displayed a weaker interaction with KPNA5 than Ebola virus VP24, which is likely to reduce the ability of Reston virus VP24 to prevent host cell interferon signalling.

CONCLUSION

Our results provide novel molecular detail on the interaction of Reston virus VP24 and Ebola virus VP24 with human KPNA5. The results indicate a weaker interaction of Reston virus VP24 with KPNA5 than Ebola virus VP24, which is probably associated with a decreased ability to interfere with the host cell interferon response. Hence, our study provides further evidence that VP24 is a key player in determining Ebolavirus pathogenicity.

Photoinactivation related dynamics of ctenophore photoproteins: Insights from molecular dynamics simulation under electric-field

Photoinactivation is a common phenomenon in bioluminescence ctenophore photoproteins (e.g mnemiopsin, berovin and BfosPP) with still unknown mechanism. The activity of coelenterate photoproteins (e.g aequorin), which has high structural similarity with ctenophore photoproteins, is not affected by light. Recently, we have characterized the effects of light on ctenophore photoprotein mnemiopsin, in different conformations, which has demonstrated light induced structural changes, uniquely secondary structures, of both apo and holo mnemiopsin. This paper is further expansion of our previous work, by applying molecular dynamics simulations to investigate photoinactivation related dynamics of berovin at atomistic level, in comparison with aequorin, under the influence of electric component of electromagnetic field. The results have indicated that the intense electric filed could influence structure of both berovin and aequorin but in different manner, whereas moderate electric field only effects on berovin's structure remarkably. In this case, increased helicity of residues E180-M193 and decreased helical contents of L38-D46 and L125-D138 segments are considerable in berovin as well as flexibility elevation of calcium binding loops. These changes cause structural expansion of berovin, especially at N-terminal domain, in direction of electric field. In conclusion, the induced structural changes of mentioned helical parts together with elevated fluctuation of their adjacent segments, N26-D46 and M193-Y206, indicate the influence of light on substrate stabilizing residues, Arg41 and Y204. This condition could presumably leads to inactivation of bioluminescence reaction due to separation of substrate from the cavity of the protein.

Perturbation of hydration layer in solvated proteins by external electric and electromagnetic fields: Insights from non-equilibrium molecular dynamics

Given the fundamental role of water in governing the biochemistry of enzymes, and in regulating their wider biological activity (e.g., by local water concentration surrounding biomolecules), the influence of extraneous electric and electromagnetic (e/m) fields thereon is of central relevance to biophysics and, more widely, biology. With the increase in levels of local and atmospheric microwave-frequency radiation present in modern life, as well as other electric-field exposure, the impact upon hydration-water layers surrounding proteins, and biomolecules generally, becomes a particularly pertinent issue. Here, we present a (non-equilibrium) molecular-dynamics-simulation study on a model protein (hen egg-white lysozyme) hydrated in water, in which we determine, inter alia, translational self-diffusivities for both hen egg-white lysozyme and its hydration layer together with relaxation dynamics of the hydrogen-bond network between the protein and its hydration-layer water molecules on a residue-per-residue basis. Crucially, we perform this analysis both above and below the dynamical-transition temperature (at ∼220 K), at 300 and 200 K, respectively, and we compare the effects of external static-electric and e/m fields with linear-response-régime (r.m.s.) intensities of 0.02 V/Å. It was found that the translational self-diffusivity of hen egg-white lysozyme and its hydration-water layer are increased substantially in static fields, primarily due to the induced electrophoretic motion, whilst the water-protein hydrogen-bond-network-rearrangement kinetics can also undergo rather striking accelerations, primarily due to the enhancement of a larger-amplitude local translational and rotational motion by charged and dipolar residues, which serves to promote hydrogen-bond breakage and re-formation kinetics. These external-field effects are particularly evident at 200 K, where they serve to induce the protein- and solvation-layer-response effects redolent of dynamical transition at a lower temperature (∼200 K) vis-à-vis the zero-field case (∼220 K).

Bioelectromagnetics Research within an Australian Context: The Australian Centre for Electromagnetic Bioeffects Research (ACEBR)

Mobile phone subscriptions continue to increase across the world, with the electromagnetic fields (EMF) emitted by these devices, as well as by related technologies such as Wi-Fi and smart meters, now ubiquitous. This increase in use and consequent exposure to mobile communication (MC)-related EMF has led to concern about possible health effects that could arise from this exposure. Although much research has been conducted since the introduction of these technologies, uncertainty about the impact on health remains. The Australian Centre for Electromagnetic Bioeffects Research (ACEBR) is a National Health and Medical Research Council Centre of Research Excellence that is undertaking research addressing the most important aspects of the MC-EMF health debate, with a strong focus on mechanisms, neurodegenerative diseases, cancer, and exposure dosimetry. This research takes as its starting point the current scientific status quo, but also addresses the adequacy of the evidence for the status quo. Risk communication research complements the above, and aims to ensure that whatever is found, it is communicated effectively and appropriately. This paper provides a summary of this ACEBR research (both completed and ongoing), and discusses the rationale for conducting it in light of the prevailing science.

Human Aquaporin 4 Gating Dynamics under Perpendicularly-Oriented Electric-Field Impulses: A Molecular Dynamics Study

Human aquaporin 4 has been studied using molecular dynamics (MD) simulations in the absence and presence of pulses of external static electric fields. The pulses were 10 ns in duration and 0.012-0.065 V/Å in intensity acting along both directions perpendicular to the pores. Water permeability and the dipolar response of all residues of interest (including the selectivity filter) within the pores have been studied. Results showed decreased levels of water osmotic permeability within aquaporin channels during orthogonally-oriented field impulses, although care must be taken with regard to statistical certainty. This can be explained observing enhanced "dipolar flipping" of certain key residues, especially serine 211, histidine 201, arginine 216, histidine 95 and cysteine 178. These residues are placed at the extracellular end of the pore (serine 211, histidine 201, and arginine 216) and at the cytoplasm end (histidine 95 and cysteine 178), with the key role in gating mechanism, hence influencing water permeability.