Helix-coil transformation and titration curve of poly-L-glutamic acid

Abstract

Abstract The titration curve of poly-L-glutamic acid was studied in connection with the helix-coil transformation. In aqueous solution the transformation has its origin in the ionization of the polar group COOH in the side chain. Conversely the ionization and the titration curve of this molecule are affected by the change of the electrostatic interaction produced by its transformation. It is shown in this report that the experimental result, the titration curve and its modified plot, can be divided into three sections, that is, the ionization of the perfect helix, the region of the helix-coil transformation, and the ionization of the perfect coil.