title: Helix-coil stability constants for the naturally occurring amino acids in water. IX. Glutamic acid parameters from random poly(hydroxybutylglutamine-co-L-glutamic acid).
abstract: The synthesis and characterization of water-soluble random copolymers containing L-glutamic acid with N5-(4-hydroxybutyl)-L-glutamine and the thermally induced helix-coil transitions of these copolymers in water and in 0.1 N KCl are described. The incorporation of L-glutamic acid was found to increase the helix content of the polymer at low pH and to decrease it at high pH even though the presence of 0.1 N KCl effectively eliminated the difference between the electrostatic free energies of the helix and the coil. The Zimm-Bragg parameters sigma and s for the helix-coil transition in poly(L-glutamic acid) in water and in 0.1 N KCl were deduced from an analysis of the melting curves of the copolymers in the manner described in earlier papers. The synthesis of N-acetyl-N'-methylglutamic acid amide and its titration, as well as that of the copolymers and poly(L-glutamic acid), in 0.1 N KCl are described.
mesh_terms: D000440:Butanols; D005971:Glutamates; D005973:Glutamine / Q000031:analogs & derivatives*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008433:Mathematics; D008968:Molecular Conformation; D008970:Molecular Weight; D010455:Peptides; D011487:Protein Conformation; D013329:Structure-Activity Relationship; D013696:Temperature; D013816:Thermodynamics
chemical_list: D000440:Butanols; D005971:Glutamates; D010455:Peptides; C010985:hydroxybutylglutamine; D005973:Glutamine