title: Stabilization of the fibrous structure of an alpha-helix-forming peptide by sequence reversal.
abstract: The alpha3-peptide, which comprises three repeats of the sequence Leu-Glu-Thr-Leu-Ala-Lys-Ala and forms an amphipathic alpha-helix, is unique among various alpha-helix-forming peptides in that it assembles into fibrous structures that can be observed by transmission electron microscopy. As part of our investigation of the structure-stability relationships of the alpha3-peptide, we synthesized the r3-peptide, whose amino acid sequence is the reverse of that of the alpha3-peptide, and we investigated the effects of sequence reversal on alpha-helix stability and the formation of fibrous structures. Unexpectedly, the r3-peptide formed a more-stable alpha-helix and longer fibers than did the alpha3-peptide. The stability of the r3-peptide helix decreased when the ionic strength of the buffer was increased and when the pH of the buffer was adjusted to 2 or 12. These results suggest that the r3-peptide underwent a "magnet-like" oligomerization and that an increase in the charge-distribution inequality may be the driving force for the formation of fibrous structures.
authors.affiliation: Institute for Biomolecular Science, Gakushuin University, Mejiro, Tokyo 171-8588, Japan. shuichi.kojima@gakushuin.ac.jp
authors.forename: Shuichi
authors.initials: S
authors.lastname: Kojima
authors.forename: Yukino
authors.initials: Y
authors.lastname: Kuriki
authors.forename: Kazumori
authors.initials: K
authors.lastname: Yazaki
authors.forename: Kin-Ichiro
authors.initials: K
authors.lastname: Miura
mesh_terms: D000595:Amino Acid Sequence; D002021:Buffers; D002942:Circular Dichroism; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D009994:Osmolar Concentration; D010455:Peptides / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015202:Protein Engineering; D020836:Protein Structure, Quaternary / Q000187:drug effects; D017433:Protein Structure, Secondary / Q000187:drug effects; D013329:Structure-Activity Relationship; D013816:Thermodynamics
chemical_list: D002021:Buffers; D010455:Peptides