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Capacity for increased surface area in the hydrophobic core of β ‐sheet peptide bilayer nanoribbons
Author(s) -
Jones Christopher W.,
Morales Crystal G.,
Eltiste Sharon L.,
YanchikSlade Francine E.,
Lee Naomi R.,
Nilsson Bradley L.
Publication year - 2021
Publication title -
journal of peptide science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 66
eISSN - 1099-1387
pISSN - 1075-2617
DOI - 10.1002/psc.3334
Subject(s) - chemistry , bilayer , hydrophobic effect , side chain , amphiphile , circular dichroism , aromatic amino acids , amino acid , steric effects , peptide , self assembly , beta sheet , crystallography , lipid bilayer , stereochemistry , organic chemistry , membrane , copolymer , biochemistry , polymer
Amphipathic peptides with amino acids arranged in alternating patterns of hydrophobic and hydrophilic residues efficiently self‐assemble into β ‐sheet bilayer nanoribbons. Hydrophobic side chain functionality is effectively buried in the interior of the putative bilayer of these nanoribbons. This study investigates consequences on self‐assembly of increasing the surface area of aromatic side chain groups that reside in the hydrophobic core of nanoribbons derived from Ac‐(XKXE) 2 ‐NH 2 peptides (X = hydrophobic residue). A series of Ac‐(XKXE) 2 ‐NH 2 peptides incorporating aromatic amino acids of increasing molecular volume and steric profile (X = phenylalanine [Phe], homophenylalanine [Hph], tryptophan [Trp], 1‐naphthylalanine [1‐Nal], 2‐naphthylalanine [2‐Nal], or biphenylalanine [Bip]) were assessed to determine substitution effects on self‐assembly propensity and on morphology of the resulting nanoribbon structures. Additional studies were conducted to determine the effects of incorporating amino acids of differing steric profile in the hydrophobic core (Ac‐X 1 KFEFKFE‐NH 2 and Ac‐(X 1,5 KFE)‐NH 2 peptides, X = Trp or Bip). Spectroscopic analysis by circular dichroism (CD) and Fourier transform infrared (FT‐IR) spectroscopy indicated β ‐sheet formation for all variants. Self‐assembly rate increased with peptide hydrophobicity; increased molecular volume of the hydrophobic side chain groups did not appear to induce kinetic penalties on self‐assembly rates. Transmission electron microscopy (TEM) imaging indicated variation in fibril morphology as a function of amino acid in the X positions. This study confirms that hydrophobicity of amphipathic Ac‐(XKXE) 2 ‐NH 2 peptides correlates to self‐assembly propensity and that the hydrophobic core of the resulting nanoribbon bilayers has a significant capacity to accommodate sterically demanding functional groups. These findings provide insight that may be used to guide the exploitation of self‐assembled amphipathic peptides as functional biomaterials.