Aviad Levin - Academia.edu (original) (raw)
Papers by Aviad Levin
Cover Picture: Solvent-Induced Self-Assembly of Highly Hydrophobic Tetra- and Pentaphenylalanine Peptides (Isr. J. Chem. 6-7/2015)
Israel Journal of Chemistry, 2015
Solvent-Induced Self-Assembly of Highly Hydrophobic Tetra- and Pentaphenylalanine Peptides
Israel Journal of Chemistry, 2015
ABSTRACT Diphenylalanine peptide (FF) self-assembles into ordered structures of notable physical ... more ABSTRACT Diphenylalanine peptide (FF) self-assembles into ordered structures of notable physical properties. Moreover, the ability of the phenylalanine amino acid or triphenylalanine to assemble into ordered nanostructures had been demonstrated. Herein, we explored the association potential of larger phenylalanine peptides, tetraphenylalanine, and pentaphenylalanine. A major challenge in studying the assembly of these peptides is their lack of solubility in different solvents. Yet, the remarkable capacity of acetic acid to solubilize FF was recently shown. Inspired by this, we examined whether this solvent could also be employed to dissolve these insoluble peptides. By utilizing the solvent-switch methodology, we revealed the self-assembly of tetraphenylalanine and pentaphenylalanine. The peptides were assembled into ordered autofluorescent elongated structures, which were further characterized by electron microscopy and spectroscopy analysis and could be utilized in future technological applications.
ACS Nano, 2014
Nanostructures composed of short, noncyclic peptides represent a growing field of research in nan... more Nanostructures composed of short, noncyclic peptides represent a growing field of research in nanotechnology due to their ease of production, often remarkable material properties, and biocompatibility. Such structures have so far been almost exclusively obtained through self-assembly from aqueous solution, and their morphologies are determined by the interactions between building blocks as well as interactions between building blocks and water. Using the diphenylalanine system, we demonstrate here that, in order to achieve structural and morphological control, a change in the solvent environment represents a simple and convenient alternative strategy to the chemical modification of the building blocks. Diphenylalanine (FF) is a dipeptide capable of self-assembly in aqueous solution into needle-like hollow micro-and nanocrystals with continuous nanoscale channels that possess advantageous properties such as high stiffness and piezoelectricity and have so emerged as attractive candidates for functional nanomaterials. We investigate systematically the solubility of diphenylalanine in a range of organic solvents and probe the role of the solvent in the kinetics of self-assembly and the structures of the final materials. Finally, we report the crystal structure of the FF peptide in microcrystalline form grown from MeOH solution at 1 Å resolution and discuss the structural changes relative to the conventional materials self-assembled in aqueous solution. These findings provide a significant expansion of the structures and morphologies that are accessible through FF self-assembly for existing and future nanotechnological applications of this peptide. Solvent mediation of molecular recognition and self-association processes represents an important route to the design of new supramolecular architectures deriving their functionality from the nanoscale ordering of their components.
Ostwald's rule of stages governs structural transitions and morphology of dipeptide supramolecular polymers
Nature communications, 2014
The self-assembly of molecular building blocks into nano- and micro-scale supramolecular architec... more The self-assembly of molecular building blocks into nano- and micro-scale supramolecular architectures has opened up new frontiers in polymer science. Such supramolecular species not only possess a rich set of dynamic features as a consequence of the non-covalent nature of their core interactions, but also afford unique structural characteristics. Although much is now known about the manner in which such structures adopt their morphologies and size distributions in response to external stimuli, the kinetic and thermodynamic driving forces that lead to their transformation from soluble monomeric species into ordered supramolecular entities have remained elusive. Here we focus on Boc-diphenylalanine, an archetypical example of a peptide with a high propensity towards supramolecular self-organization, and describe the pathway through which it forms a range of nano-assemblies with different structural characteristics. Our results reveal that the nucleation process is multi-step in natur...
PLoS ONE, 2011
An increasing body of evidence indicates that accumulation of soluble oligomeric assemblies of b-... more An increasing body of evidence indicates that accumulation of soluble oligomeric assemblies of b-amyloid polypeptide (Ab) play a key role in Alzheimer's disease (AD) pathology. Specifically, 56 kDa oligomeric species were shown to be correlated with impaired cognitive function in AD model mice. Several reports have documented the inhibition of Ab plaque formation by compounds from natural sources. Yet, evidence for the ability of common edible elements to modulate Ab oligomerization remains an unmet challenge. Here we identify a natural substance, based on cinnamon extract (CEppt), which markedly inhibits the formation of toxic Ab oligomers and prevents the toxicity of Ab on neuronal PC12 cells. When administered to an AD fly model, CEppt rectified their reduced longevity, fully recovered their locomotion defects and totally abolished tetrameric species of Ab in their brain. Furthermore, oral administration of CEppt to an aggressive AD transgenic mice model led to marked decrease in 56 kDa Ab oligomers, reduction of plaques and improvement in cognitive behavior. Our results present a novel prophylactic approach for inhibition of toxic oligomeric Ab species formation in AD through the utilization of a compound that is currently in use in human diet.
Cover Picture: Solvent-Induced Self-Assembly of Highly Hydrophobic Tetra- and Pentaphenylalanine Peptides (Isr. J. Chem. 6-7/2015)
Israel Journal of Chemistry, 2015
Solvent-Induced Self-Assembly of Highly Hydrophobic Tetra- and Pentaphenylalanine Peptides
Israel Journal of Chemistry, 2015
ABSTRACT Diphenylalanine peptide (FF) self-assembles into ordered structures of notable physical ... more ABSTRACT Diphenylalanine peptide (FF) self-assembles into ordered structures of notable physical properties. Moreover, the ability of the phenylalanine amino acid or triphenylalanine to assemble into ordered nanostructures had been demonstrated. Herein, we explored the association potential of larger phenylalanine peptides, tetraphenylalanine, and pentaphenylalanine. A major challenge in studying the assembly of these peptides is their lack of solubility in different solvents. Yet, the remarkable capacity of acetic acid to solubilize FF was recently shown. Inspired by this, we examined whether this solvent could also be employed to dissolve these insoluble peptides. By utilizing the solvent-switch methodology, we revealed the self-assembly of tetraphenylalanine and pentaphenylalanine. The peptides were assembled into ordered autofluorescent elongated structures, which were further characterized by electron microscopy and spectroscopy analysis and could be utilized in future technological applications.
ACS Nano, 2014
Nanostructures composed of short, noncyclic peptides represent a growing field of research in nan... more Nanostructures composed of short, noncyclic peptides represent a growing field of research in nanotechnology due to their ease of production, often remarkable material properties, and biocompatibility. Such structures have so far been almost exclusively obtained through self-assembly from aqueous solution, and their morphologies are determined by the interactions between building blocks as well as interactions between building blocks and water. Using the diphenylalanine system, we demonstrate here that, in order to achieve structural and morphological control, a change in the solvent environment represents a simple and convenient alternative strategy to the chemical modification of the building blocks. Diphenylalanine (FF) is a dipeptide capable of self-assembly in aqueous solution into needle-like hollow micro-and nanocrystals with continuous nanoscale channels that possess advantageous properties such as high stiffness and piezoelectricity and have so emerged as attractive candidates for functional nanomaterials. We investigate systematically the solubility of diphenylalanine in a range of organic solvents and probe the role of the solvent in the kinetics of self-assembly and the structures of the final materials. Finally, we report the crystal structure of the FF peptide in microcrystalline form grown from MeOH solution at 1 Å resolution and discuss the structural changes relative to the conventional materials self-assembled in aqueous solution. These findings provide a significant expansion of the structures and morphologies that are accessible through FF self-assembly for existing and future nanotechnological applications of this peptide. Solvent mediation of molecular recognition and self-association processes represents an important route to the design of new supramolecular architectures deriving their functionality from the nanoscale ordering of their components.
Ostwald's rule of stages governs structural transitions and morphology of dipeptide supramolecular polymers
Nature communications, 2014
The self-assembly of molecular building blocks into nano- and micro-scale supramolecular architec... more The self-assembly of molecular building blocks into nano- and micro-scale supramolecular architectures has opened up new frontiers in polymer science. Such supramolecular species not only possess a rich set of dynamic features as a consequence of the non-covalent nature of their core interactions, but also afford unique structural characteristics. Although much is now known about the manner in which such structures adopt their morphologies and size distributions in response to external stimuli, the kinetic and thermodynamic driving forces that lead to their transformation from soluble monomeric species into ordered supramolecular entities have remained elusive. Here we focus on Boc-diphenylalanine, an archetypical example of a peptide with a high propensity towards supramolecular self-organization, and describe the pathway through which it forms a range of nano-assemblies with different structural characteristics. Our results reveal that the nucleation process is multi-step in natur...
PLoS ONE, 2011
An increasing body of evidence indicates that accumulation of soluble oligomeric assemblies of b-... more An increasing body of evidence indicates that accumulation of soluble oligomeric assemblies of b-amyloid polypeptide (Ab) play a key role in Alzheimer's disease (AD) pathology. Specifically, 56 kDa oligomeric species were shown to be correlated with impaired cognitive function in AD model mice. Several reports have documented the inhibition of Ab plaque formation by compounds from natural sources. Yet, evidence for the ability of common edible elements to modulate Ab oligomerization remains an unmet challenge. Here we identify a natural substance, based on cinnamon extract (CEppt), which markedly inhibits the formation of toxic Ab oligomers and prevents the toxicity of Ab on neuronal PC12 cells. When administered to an AD fly model, CEppt rectified their reduced longevity, fully recovered their locomotion defects and totally abolished tetrameric species of Ab in their brain. Furthermore, oral administration of CEppt to an aggressive AD transgenic mice model led to marked decrease in 56 kDa Ab oligomers, reduction of plaques and improvement in cognitive behavior. Our results present a novel prophylactic approach for inhibition of toxic oligomeric Ab species formation in AD through the utilization of a compound that is currently in use in human diet.