During injured tissue regeneration, the extracellular matrix plays a key role in controlling and coordinating various cellular events by binding and releasing secreted proteins in addition to ...promoting cell adhesion. Herein, we develop a cell-adhesive fiber-forming peptide that mimics the jigsaw-shaped hydrophobic surface in the dovetail-packing motif of glycophorin A as an artificial extracellular matrix for regenerative therapy. We show that the jigsaw-shaped self-assembling peptide forms several-micrometer-long supramolecular nanofibers through a helix-to-strand transition to afford a hydrogel under physiological conditions and disperses homogeneously in the hydrogel. The molecular- and macro-scale supramolecular properties of the jigsaw-shaped self-assembling peptide hydrogel allow efficient incorporation and sustained release of vascular endothelial growth factor, and demonstrate cell transplantation-free regenerative therapeutic effects in a subacute-chronic phase mouse stroke model. This research highlights a therapeutic strategy for injured tissue regeneration using the jigsaw-shaped self-assembling peptide supramolecular hydrogel.
The gel-sol transition of self-assembling peptides is a useful switch for environment-dependent drug release. For their applications, kinetics control of the responses is important for matching the ...velocity of release to the target biological events. Here we demonstrate the chemical control of redox-triggered gel-sol transition kinetics of self-assembling peptides by altering the amino acid sequence. Amphiphilic peptides were developed in which a methionine residue was located in the middle (JigSAP-IMI) or near the N terminus (JigSAP-MII). Both peptides formed hydrogels under physiological conditions-forming β-sheet-based supramolecular nanofibers. In contrast, the oxidized forms remained in the solution state under identical conditions-adopting α-helix-rich secondary structures. Upon oxidation with H
O
, a reactive oxygen species, JigSAP-MII showed a faster gel-to-sol transition and cargo-releasing than JigSAP-IMI, thus indicating that the phase-transition and releasing kinetics of self-assembling peptides can be rationally controlled by the position of the reactive amino acid residue.
Hyper‐Raman (HR) spectroscopy reveals unique information about molecular structures, because of its different selection rule, compared with that of the infrared (IR) and Raman spectroscopy. The ...application of HR spectroscopy on biomolecules' research has been expected for a long time. Herein, we report the HR spectra of the amino acids tryptophan (Trp), tyrosine (Tyr), histidine, and bovine serum albumin (BSA) in aqueous solution, obtained at an excitation wavelength of 532 nm. The HR bands of BSA were mostly assigned to those of the aromatic amino acids. The predominance of the aromatic amino acids was explained by considering the resonance effect of the excitation beam to the electronic absorption around 266 nm, the double frequency of 532 nm (e.g. La of Trp, Lb of Tyr). Besides the Raman bands observed in the 266‐nm‐excited ultraviolet resonance Raman spectrum, some of the IR‐active bands of Tyr were also detected. Hence, the HR spectroscopy serves as a new tool toward the investigation of proteins as well as of biomolecules and more complicated biological structures with the 532‐nm excitation.
The 532‐nm‐excited hyper‐Raman spectrum of protein is reported. Two‐photon resonance effect to the electronic transition at 266 nm explains selective detection of the HR signals of Trp and Tyr side chains. The 532‐nm‐excited hyper‐Raman spectroscopy derives the structural information equivalent to those from UV resonance Raman spectroscopy in protein structure analysis.
Peptides provide a framework for generating functional biopolymers. In this study, the pH-dependent structural changes in the 21-29 fragment peptide of β
-microglobulin (β
m
) during ...self-aggregation, i.e., the formation of an amyloid fibril, were discussed. The β-sheet structures formed during parallel stacking under basic conditions (pH ≥ 7.7) adopted an anti-parallel stacking configuration under acidic conditions (pH ≤ 7.6). The parallel and anti-parallel β-sheets existed separately at the intermediate pH (pH = 7.6-7.7). These results were attributed to the rigidity of the β-sheets in the fibrils, which prevented the stable hydrogen bonding interactions between the parallel and anti-parallel β-sheet moieties. This observed pH dependence was ascribed to two phenomena: (i) the pH-dependent collapse of the β
m
fibrils, which consisted of 16 ± 3 anti-parallel β-sheets containing a total of 2000 β-strands during the deprotonation of the NH
group (pK
= 8.0) of the β-strands that occurred within 0.7 ± 0.2 strands of each other and (ii) the subsequent formation of the parallel β-sheets. We propose a framework for a functional biopolymer that could alternate between the two β-sheet structures in response to pH changes.
This paper reports the hyper‐Raman (HR) spectra of the 20 amino acids in aqueous solution in the range of 400–1,800 cm−1 with an excitation wavelength of 532 nm. A remarkable common feature in the ...nonresonance HR spectra is the large intensity of the HR bands of the COO− group. Whereas the peak position is mostly identical between the HR and Raman spectra, the intensity pattern is not. We discuss the similarities and dissimilarities between the pattern of the two spectra of each amino acid and give possible assignments to each HR band by comparing them with those of the corresponding Raman band. This study offers a reference for the HR spectra of the amino acids as the basic building block of proteins. It helps interpret the HR spectra of proteins and peptides.
This paper reports the hyper‐Raman (HR) spectra of the 19 amino acids (20 except for Phe) with an excitation wavelength of 532 nm. Similarities and dissimilarities with the Raman spectrum are described, and possible assignment is given for each HR band. The data set offers a reference to study the structures of proteins and peptides with the HR spectroscopy.
Disulfide bonds play a fundamental role in controlling the tertiary structure of proteins; the formation or cleavage of some disulfide bonds can switch the structures and/or functions of proteins. ...Human galectin-1 (hGal-1), which is a lectin protein, exemplifies how both structure and function are changed by disulfide bonds; the structure and sugar-binding ability of hGal-1 are altered by the formation and cleavage of its three intra-molecular disulfide bonds. In the present study, the dynamics of the structural change of hGal-1 by the formation of disulfide bonds were investigated by time-resolved FTIR spectroscopy combined with a modification in which its thiol groups (-SH) were replaced with S-nitrosylated groups (SNO). Photodissociation of NO from SNO in reduced hGal-1 induced disulfide bond formation and transformed it into the oxidised form. The structural change to the oxidised form involved three distinct kinetics with fast (<300 s), middle (∼600 s), and slow (∼6400 s) lifetimes. In an examination of hGal-1 in the lactose-bound form, structural changes owing to the release of substrate lactose were also observed upon disulfide bond formation. The present method using the photodissociation of NO is useful for monitoring the dynamics of structural changes following disulfide formation.
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•1-hydroxyacetone is found to exist in the equilibrium of dimer, monomer, and enol structures in 1,4-dioxane.•Structure of each tautomer is characterized from response to electric ...field modulation.•Infrared electroabsorption spectroscopy enabled analyzing the response to the modulation.•Electric field of 5 × 106 V m−1 is found to change the fraction of each tautomer in the order of 10−3%.
Electric field effect was investigated on 1-hydroxyacetone (HA) as a model compound of the acyclic form of saccharide moiety employing infrared electroabsorption spectroscopy. We examined the structural tautomerization of the hydroxyacetyl group of HA in detail by monitoring change in IR absorption intensity of the CO stretching band in the range of 1650–1850 cm−1. The observed changes in absorbance were analyzed by considering a change in the equilibrium of HA dimer, HA monomer, endiol, and enol forms, as well as the orientational polarization of each tautomer. Conversion from the HA dimer to the enol was detected.
Proton transport properties of a partially protonated poly(aspartic acid)/sodium polyaspartate (P-Asp) were investigated. A remarkable enhancement of proton conductivity has been achieved in the thin ...film. Proton conductivity of 60-nm-thick thin film prepared on MgO(100) substrate was 3.4 × 10–3 S cm–1 at 298 K. The electrical conductivity of the oriented thin film was 1 order of magnitude higher than the bulk specimen, and the activation energies for the proton conductivity were 0.34 eV for the oriented thin film and 0.65 eV for the pelletized sample, respectively. This enhancement of the proton transport is attributable to the highly oriented structure on MgO(100) substrate. This result proposes great potential for a new strategy to produce a highly proton-conductive material using the concept of an oriented thin film structure without strong acid groups.
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