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Solvent‐ and salt‐induced coil–helix transition of alkali metal salts of poly( L ‐glutamic acid) in aqueous organic solvents
Author(s) -
Satoh Mitsuru,
Fujii Yoshitake,
Kato Fusaaki,
Komiyama Jiro
Publication year - 1991
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360310102
Subject(s) - chemistry , alkali metal , aqueous solution , counterion , solvent , inorganic chemistry , salt (chemistry) , helix (gastropod) , transition metal , solvent effects , ion , organic chemistry , catalysis , ecology , snail , biology
The coil–helix transition has been studied for alkali metal salts of poly ( L ‐glutamic acid) (PLG), i.e., PLGLi, ‐Na, ‐K, and ‐Cs, in aqueous organic solvent systems. Dependence of the transition on the solvent composition has been qualitatively discussed in terms of the solvent dielectric constant D , Gutmann's acceptor number AN, and water activity a w . The helix formation induced by addition of alkali chlorides has also been studied. The sharpness of the transition has been interpreted as a measure of reduction of electrostatic energy of helical PLG through contact ion‐pair formation between a counterion and carboxyl anion.