title: Effects of the sequence and size of non-polar residues on self-assembly of amphiphilic peptides.
abstract: Peptides with alternating hydrophobic and polar amino acids have been shown to form stable beta-sheet secondary structures and self-assemble into hydrogel-like matrices in the presence of physiological salt concentrations. We hypothesized that the sequence and steric size differences of non-polar residues can affect the balance of peptide intermolecular forces in solution that drive self-assembly. To test this hypothesis, we designed a library of artificial amphiphilic peptides based on the sequence (FEFEFKFK)2 by substituting combinations of the non-polar residues glycine, alanine, valine, leucine and isoleucine for phenylalanine. Peptide structure and self-assembly were characterized using scanning electron microscopy, the Thioflavin T assay, transmission electron microscopy, X-ray fiber diffraction and circular dichroism spectroscopy. The sequence and steric size of non-polar residues are shown to cause variations in peptide secondary structures and create significant differences in the matrix morphology of self-assembled peptides.
authors.affiliation: Department of Chemical Engineering, University of California, Berkeley, CA 94720, USA. kai.wang@berkeley.edu
authors.forename: Kai
authors.initials: K
authors.lastname: Wang
authors.forename: Jay D
authors.initials: JD
authors.lastname: Keasling
authors.forename: Susan J
authors.initials: SJ
authors.lastname: Muller
mesh_terms: D000409:Alanine / Q000737:chemistry; D020816:Amino Acid Motifs; D000682:Amyloid / Q000737:chemistry; D052160:Benzothiazoles; D002942:Circular Dichroism; D003224:Congo Red / Q000494:pharmacology; D015723:Gene Library; D005998:Glycine / Q000737:chemistry; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry; D007532:Isoleucine / Q000737:chemistry; D007930:Leucine / Q000737:chemistry; D046911:Macromolecular Substances / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry*; D010649:Phenylalanine / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D013696:Temperature; D013844:Thiazoles / Q000737:chemistry; D014466:Ultraviolet Rays; D014633:Valine / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D000682:Amyloid; D052160:Benzothiazoles; D046911:Macromolecular Substances; D010455:Peptides; D013844:Thiazoles; D007532:Isoleucine; C009462:thioflavin T; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D003224:Congo Red; D010649:Phenylalanine; D007930:Leucine; D014633:Valine; D000409:Alanine; D005998:Glycine