Spontaneous Fiber Formation and Hydrogelation of Nucleotide Bolaamphiphiles

Iwaura, Rika; Yoshida, Kaname; Masuda, Mitsutoshi; Yase, and Kiyoshi; Shimizu, Toshimi

doi:10.1021/cm020263n

Cited by 171 publications

(128 citation statements)

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“…For a gel in a water-rich environment, which is called a hydrogel, water participates in hydrogen bonding through bridging of charged groups (30,49,50). Self-assembled hydrogels, such as the tau 2-19 peptide gel, are characterized by the property of shear thinning, as observed here, wherein the gel viscosity decreases upon application of a force, such as that imposed by pipetting, and increases once the force is removed (30).…”

Section: Water and Hydrogen Bonding In The Tau 2-19 Gel Networkmentioning

confidence: 83%

Comparative Vibrational Spectroscopy of Intracellular Tau and Extracellular Collagen I Reveals Parallels of Gelation and Fibrillar Structure

Juszczak

2004

Journal of Biological Chemistry

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The N-terminal tau 2-19 peptide undergoes gelation, syneresis, and aggregation over a period of years. These changes may be approximated on a shorter time scale by agitation and partial dehydration. The anomalously enhanced (229 nm) ultraviolet resonance Raman (UVRR) imide II band reveals a common structural feature for gels of nondehydrated tau 2-19 and collagen I and insoluble paired helical filaments (PHFs) and collagen I of weak hydrogen bonding at proline carbonyls. Anomalous UVRR enhancement of amide bands at 229 nm results from gel structure, as demonstrated by increased amide absorption at the red edge for tau 2-19 gel and implies the involvement of water in gel structure. In aged, dehydrated tau 2-19 gel, proline carbonyls lose their bonds to water and tyrosine becomes deprotonated, as demonstrated by UVRR spectroscopy. The Fourier transform infrared (FTIR) amide I band shows that antiparallel ␤-sheet structure increases with syneresis in the tau 2-19 hydrogel. The comparison of FTIR results for PHFs with collagen I gel and polyproline demonstrates that the secondary structure of PHFs is polyproline II. One implication of this assignment is that the fibrillation of hydrophilic tau is thermodynamically driven by the entropy gained as hydrogen-bonded water is freed, as for collagen I. The FTIR results also show that peptide domains culled from a longer protein do not necessarily fold into identical secondary structures. A pathological, sequential mechanism of gelation, syneresis, and fibrillation for tau in AD is suggested and is supported by the observation of amorphous neurofibrillary tangle development and fibrillation in vivo.The cytomatrix is a living, insoluble, thixotropic gel (1) that is dynamic because its structure may change from fluid (sol) to elastic (gel) and back again; the filamentous network is constantly changing (2). Its constituent, organized structures are polymeric microtubules, actin microfilaments, and intermediate filaments (2). The assembly of this gel network and the composite fibrils is assisted through interactions with a number of other proteins. Within the set of microtubule assembling proteins, tau is of particular interest.In healthy neurons, tau, through its control of the reversible polymerization of microtubules, participates in the extension of both axons and neuritic processes, also known as neural growth cone development, and in the development of neural polarity (3). In a post-translationally modified state, however, tau is responsible for several neurodegenerative diseases or tauopathies, one of which is Alzheimer's disease (AD), 1 characterized by intraneuronal inclusions of phosphorylated tau that are initially amorphous. Over time, the intraneuronal inclusions of tau isoforms (4 -6) self-assemble into paired helical filaments (PHFs) (7, 8); these are responsible for the neurofibrillary tangles found in AD.Braak and Braak (9 -11) have demonstrated the correlation between cognitive decline and the development of the tau neurofribrillary tangles. The progression of...

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Section: Water and Hydrogen Bonding In The Tau 2-19 Gel Networkmentioning

confidence: 83%

Comparative Vibrational Spectroscopy of Intracellular Tau and Extracellular Collagen I Reveals Parallels of Gelation and Fibrillar Structure

Juszczak

2004

Journal of Biological Chemistry

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“…169 In particular, the longer homologue 25(20) can form robust hydrogels with Mill-Q water and the buffer solutions (> pH 4.01) (Figure 25). We found that the gelation of water by 25(20) can be achieved even at concentrations of 0.2 wt% (> 25000 water molecules per hydrogelator molecule).…”

Section: Nanofiber Formation From Nucleotide-appended Bolaamphiphilicmentioning

confidence: 99%

Bottom-Up Synthesis and Morphological Control of High-Axial-Ratio Nanostructures through Molecular Self-Assembly

Shimizu

2003

Polym J

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ABSTRACT:Based on our recent results, the present paper overviews noncovalent formation of high-axial-ratio nanostructures (HARNs), such as fibers, rods, tubes and ropes, through molecular self-assembly of bola-form amphiphilic (bolaamphiphilic) monomers. A variety of bolaamphiphiles, in which sugars, peptides, or nucleobases as headgroups are connected to both ends of a hydrocarbon spacer, were newly designed and synthesized. Their self-assembling behavior was examined in aqueous solutions in terms of bottom-up fabrication of organic nanostructures. The morphologies proved to strongly depend on the headgroup structure, spacer chain lengths and even-odd carbon numbers of used oligo(methylene) spacers. Typical examples of self-assembled morphologies include nanofibers from 1-glucosamide-or thymidine-appended bolaamphiphiles, vesicle-encapsulated microtubes from glycylglycine-appended bolaamphiphiles, double-helical ropes from thymine-appended bolaamphiphiles. These self-assembled HARNs are constructed hierarchically in a manner similar to biological structures. On the basis of several solid-state analyses, molecular packing and orientation within the HARNs are discussed and compared with the single crystal structures in terms of hydrogen-bond networks. Furthermore, pH-dependent reversible polymer formation was achieved using the combination of glucuronamideand aromatic boronic acid-appended bola-form derivatives. Polymerization of bola-form 1-glucosamide derivatives with a 1,4-butadiyne group was performed in self-assembled nanometer-sized fibers, giving a single polydiacetylene chain of 64-mer that can be seen in TEM.KEY WORDS High-Axial-Ratio Nanostructure (HARN) / Bolaamphiphile / Self-Assembly / Noncovalent Synthesis / Hydrogen Bond / Nanofiber / Microtube / Nano-Rod / Rope / Hydrogel / Crystal Structure / Biomaterials possess highly organized non-covalent structures formed spontaneously in bottom-up fashion, 1 shaping natural body and functioning as energyconverting and information-converting materials. In contrast, conventional polymers are so-called linear macromolecules in which tens of thousands to millions of low-molecular-weight monomer units are connected to each other through covalent bonds. Very recently, a new family of polymers, including topologically complex polymers 2-13, 18-25 and self-assembled nanostructures, [14][15][16][17]26 has attracted much attention. 27,28 In particular, Kunitake and his co-worker built up the fundamental concept behind the polymolecular materials based on bilayer-containing molecular assemblies. 29,30 Stupp et al., 31, 32 Percec et al., 33 and Whitesides et al. 34,35 also succeeded in a molecule-up fabrication using polymer building blocks to realize nanometersized assemblies with well-defined shapes. The advantage of non-covalent self-assembly technique, unlike chemical reaction or polymerization, is in that it can directly produce ordered two-and three-dimensional structures like sheets, rods, fibers, tubes, disks, and spheres. It is more important that nanostruct...

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“…4 These ribbons and tubules are single crystals that represent metastable intermediates in a crystallization pathway proceeding from filaments to plate-like crystals. 4 Nucleobase -derived amphiphiles can also form helical and tubular structures, as described for phospholipid -nucleoside conjugates 5 as well as for different single-and double-chain amphiphilic nucleobase derivatives prepared either via covalent modification 6 or by electrostatic complexation. 7 The formation of these supramolecular structures is attributed to the combination of the aggregation properties of the lipid part (hydrophobic effect) with the hydrogen bonding and π-π stacking of the nucleobase moieties.…”

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confidence: 99%