Solvent-Induced Handedness Inversion of Dipeptide Sodium Salts Derived from Alanine

Abstract

The relationship between amino acid sequences and their resulting nanostructure has been well studied, but that between amino acid chirality and nanostructure handedness has not. Four dipeptide sodium salts with long alkyl chains derived from L- and D-alanines were synthesized. The behavior of their self-assembly into physical gels in water and THF was studied using field-emission scanning electron microscopy, circular dichroism (CD), FT-IR spectroscopy, (1)H NMR spectroscopy, and X-ray diffraction. The dipeptide salts organized into twisted nanoribbons, whose handedness was controlled by the terminal alanine chirality. The handedness of nanoribbons formed in water was opposite to that of those formed in THF. The dipeptide salts self-assembled into similar interdigitated bilayer structures in water and THF, but CD spectra of the gels indicated that the stacking of carbonyl groups was opposite. The formation of this handedness inversion is proposed to arise from the difference in interlayer distance and chiral stacking of carbonyl groups near the C-terminals.

Helicity of perfluoroalkyl chains controlled by the self‐assembly of the Ala‐Ala dipeptides

“…The handedness of the nanofibers of (L, D)‐ F1 was left, while (D, L)‐ F1 was right. Previous study of lipodipeptides also derived from alanine dipeptide by our group suggested that the handedness of the self‐assemblies was controlled by the chirality of the alanine at the C ‐terminal . On the contrary, in this case, the chirality of alanine at N ‐terminal determined the handedness of the self‐assemblies.…”

“…The handedness of the self‐assemblies was dominated by the chirality of amino acids. Lipodipepitdes along with some amphiphilic peptides with short peptide sequence underwent self‐assembly process and then formed helical or twisted nanostructures in either aqueous or organic solvents. In the case of homogeneous lipodipeptides, further study indicated that the chirality of amino acid at C‐terminal determined the handedness of nanostructures and the stacking handedness of the molecules …”

“…In the case of homogeneous lipodipeptides, further study indicated that the chirality of amino acid at C-terminal determined the handedness of nanostructures and the stacking handedness of the molecules. 10,11,13 Opposite to conventional hydrocarbon chains that prefer to maintain an all-trans conformation, linear perfluoroalkyl chains have already been found to intrinsically adopt helical structures in both crystalline and solution states. 14,15 The helicity was first ascribed as the consequence of steric hindrance and electrostatic repulsion of fluorine atoms.…”

Left‐handed helical polymer resin nanotubes prepared by using N‐palmitoyl glucosamine

“…Because morphologies of organic self-assembled structures are usually sensitive to the solvent, 31 it is reasonable to assume that the morphology of the M-PR can be tuned by changing the solvent ratio. Indeed, when a mixture of methanol and water (25:50, vol/vol) was used as the solvent, short nanotubes were obtained ( Figure 6A), and when a mixture of methanol and water (40:50, vol/vol) was used, shrunken hollow spheres were identified ( Figure 6B).…”

1,1,1,3,3,3-Hexafluoro-2-propanol and 2,2,2-trifluoroethanol solvents induce self-assembly with different surface morphology in an aromatic dipeptide

“…7,9 It has been shown that aromatic dipeptides have the ability to adopt different types of structural morphologies, such as nanotubes, microtubes, nanowires, nanofibers, microcrystals, vesicles, and organogels, depending on the substrate, solvent, temperature and pH. 8,[10][11][12][13][14][15][16][17][18][19][20][21][22] The dipeptides containing non-aromatic amino acids also show stable self-assembled structures, indicating that aromaticity may not be absolutely required for self-assem- † Electronic supplementary information (ESI) available: Representative SEM images of the YF self-assembled structure derived from HFIP solution, CD of YF in methanol and optical images of the self-assembled structure derived from methanol solution, time-dependent CD spectra of YF in 10% HFIP-90% TFE solvent mixture at 1 mg ml −1 concentration, plot of change in CD ellipticity as a function of time for YF in different solvent mixtures (90% HFIP-10% TFE, 50% HFIP-50% TFE, 10% HFIP-90% TFE, 90% TFE-10% HFIP, 50% TFE-50% HFIP, and 10% TFE-90% HFIP, v/v), and time-dependent FTIR spectra of the YF selfassembled structure derived from 10% HFIP-90% TFE solvent mixture. See DOI: 10.1039/c4ob00821a a Bioorganic Laboratory, CSIR-Central Leather Research Institute, Adyar, Chennai-600020, India.…”