Helix-Coil Transition and Association Behavior of Water-Soluble Polypeptides Having Hydrophobic Alkyl Side Chains

  • Katsuhiro InomataEmail author
  • Tomokazu Takai
  • Noriyoshi Ohno
  • Yoshiaki Yamaji
  • Erina Yamada
  • Hideki Sugimoto
  • Eiji Nakanishi
Conference paper
Part of the Progress in Colloid and Polymer Science book series (PROGCOLLOID, volume 136)


Water soluble polypeptide, poly[N 5-(2-hydroxyethyl) L-glutamine] (PHEG), was hydrophobiocally modified partially along the main chain by long alkyl groups -(CH2) n–1CH3 (Cn) as side chains. Association and viscoelastic behavior of solutions of these self-assembling polymers (PHEG-g-Cn, n = 12, 16 and 18) were investigated by means of steady-flow viscosity and linear dynamic viscoelasticity measurements. In the mixed solvent of water/ethylene glycol (EG), the main chain of PHEG-g-Cn changed its conformation from flexible random coil to rodlike α-helix with the increase in EG content of the solvent. When the solvent was pure water, existence of the associative alkyl chains induced a drastic increase in shear flow viscosity (η) than PHEG homopolymer, probably because of formation of self-assembled large aggregates via intermolecular association. When EG was used as solvent, η and the elastic storage modulus (G′) of the solution revealed a unique concentration dependence, i.e., η and G′ of PHEG-g-C18 solution at 20 wt% were smaller than those at 15 wt%. These viscoelastic behaviors may be described by the α-helical rodlike conformation of PHEG main chain, which is suitable to form an ordered anisotropic phase like lyotropic liquid crystal, with destruction of a physically crosslinked network structure.


Polypeptides Association Viscoelastisity Associative polymers Helix-coil transition 



We would like to acknowledge the financial support by Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science (No. 15550105 and No. 18550193).


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Copyright information

© Springer-Verlag Berlin Heidelberg 2009

Authors and Affiliations

  • Katsuhiro Inomata
    • 1
    Email author
  • Tomokazu Takai
  • Noriyoshi Ohno
  • Yoshiaki Yamaji
  • Erina Yamada
  • Hideki Sugimoto
  • Eiji Nakanishi
  1. 1.Department of Materials Science and EngineeringNagoya Institute of TechnologyNagoyaJapan

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