Oppositely Charged Homopolypeptides Form Ordered Helix Assemblies With Hierarchical Structure

Small, pp. e75495

Abstract

Oppositely charged polyelectrolytes are known to form polyelectrolyte complexes. Polyelectrolyte complexes are typically structurally disordered. In recent years, complexes of oppositely charged polypeptides have received increasing attention. Polypeptides provide additional interaction motifs such as hydrogen bonds and salt bridges that could stabilize ordered assemblies. Under specific conditions, the formation of secondary structures has been reported. So far, it has been difficult to obtain long-range ordered assemblies of polypeptide complexes. Here we show that liquid-solid phase separation of oppositely charged homopolypeptides spontaneously leads to the formation of extended polypeptide helices that form highly ordered hexagonally or square-packed helix arrays with helix-helix distances of 1.6-2.0 nm. The helices exhibit an additional periodic staggering along their axis with a periodicity of 15 - 30 nm, equal to the length of the extended helices. This hierarchical helix assembly was demonstrated for polyarginine assembled with polyaspartic acid or polyglutamic acid as examples. The materials can be shear-aligned to achieve macroscopic uniaxial orientation of the helices. Crosslinking leads to solid elastic materials. Upon heating to temperatures above 40°C, the structure disorders due to a reversible helix-coil transition. The structural and mechanical properties suggest a new route to synthetic peptide-based materials.

Authors 11

1. Ekaterina Buvalaia

   Forschungszentrum Jülich

   Affiliation as printed

   JCNS‐1 Forschungszentrum Jülich Jülich Germany

2. Martin Dulle

   Forschungszentrum Jülich

   Affiliation as printed

   JCNS‐1 Forschungszentrum Jülich Jülich Germany

3. Benoît David

   Forschungszentrum Jülich

   Affiliation as printed

   IBG‐4 Forschungszentrum Jülich Jülich Germany

4. Karoline Rengel

   Forschungszentrum Jülich

   Affiliation as printed

   JCNS‐1 Forschungszentrum Jülich Jülich Germany

5. Michael Ohl

   Forschungszentrum Jülich

   Affiliation as printed

   JCNS‐1 Forschungszentrum Jülich Jülich Germany

6. Beate Förster

   Forschungszentrum Jülich · Ernst Ruska Centre

   Affiliation as printed

   ERC‐1 Forschungszentrum Jülich Jülich Germany

7. Margarita Kruteva

   Forschungszentrum Jülich

   Affiliation as printed

   JCNS‐1 Forschungszentrum Jülich Jülich Germany

8. Henrike Heise

   Forschungszentrum Jülich · Heinrich Heine University Düsseldorf

   Affiliation as printed

   IBI‐7 Forschungszentrum Jülich Jülich Germany

   Institute For Physical Chemistry Heinrich Heine University Düsseldorf Düsseldorf Germany

9. Ralf Biehl

   Forschungszentrum Jülich

   Affiliation as printed

   JCNS‐1 Forschungszentrum Jülich Jülich Germany

10. Holger Gohlke

    Forschungszentrum Jülich · Heinrich Heine University Düsseldorf

    Affiliation as printed

    IBG‐4 Forschungszentrum Jülich Jülich Germany

    Institute For Pharmaceutical and Medicinal Chemistry Heinrich Heine University Düsseldorf Düsseldorf Germany

11. Stephan Förster corresponding Aachen Institute of Physical Chemistry

    Forschungszentrum Jülich · RWTH Aachen University

    Affiliation as printed

    Institute of Physical Chemistry RWTH Aachen University Aachen Germany

    JCNS‐1 Forschungszentrum Jülich Jülich Germany