Complex Formation of
a Collagen Model Peptide with
Polyelectrolytes and Stabilization of
the Triple Helical Structure

Small-angle X-ray scattering (SAXS) measurements were made for a collagen model peptide, H-(Gly-Pro-4-(R)-Hyp)9-OH (GPO9) with or without sodium polyacrylate (NaPAA) in 20 mM and 100 mM aqueous NaCl at 15 °C and 75 °C. At 15 °C, almost all triple helical peptides form a complex with NaPAA when the molar ratio of acrylic acid unit to peptide molecules is not smaller than 10 whereas they are molecularly dispersed at 75 °C. Furthermore, the attached triple helices appreciably extend the main chain of NaPAA, and the radius of gyration for the complex is at most twice larger than the single NaPAA chain. Circular dichroism measurements demonstrated that the complexation noticeably stabilizes the triple helical structure.

(by K. Terao, R. Kanenaga & T. Sato)

Chart 1. Chemical structures of materials investigated.

Fig. 1. Mixing ratio dependence of the zero-scattering angle intensity of SAXS for a mixture of NAPAA and GPO in 20 mM (triangles) and 100 mM (circles) aqueous NaCl at 15 and 75 °C, and the schematic representation of complex formation for investigated α at 15 °C.

Fig. 2. Tm for GPO9 including NaPAA in pure water, 20 mM, and 100 mM aqueous NaCl.