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Counterion binding in partially neutralized poly( D ‐glutamic acid) and poly( DL ‐glutamic acid)
Author(s) -
Sugai Shintaro,
Nitta Katsutoshi
Publication year - 1969
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.1969.360070407
Subject(s) - counterion , chemistry , glutamic acid , polyelectrolyte , acrylic acid , polymer chemistry , counterion condensation , sodium , neutralization , sodium salt , inorganic chemistry , amino acid , organic chemistry , monomer , polymer , ion , biochemistry , antibody , immunology , biology
Sodium counterion association with partially neutralized poly( D ‐glutamic acid) or poly( DL ‐glutamic acid) was measured by use of Wall's transference method with radioactive sodium. In the region where both polyacids are in completely random coil form, fractions of association were considerably less than that with poly(acrylic acid) in the same region of degree of neutralization. Even in the region where poly ( D ‐glutamic acid) is in the helical form, the fraction of association was less than that with poly(acrylic acid) in the same region. No pronounced characteristics attributable to counterion association corresponding to the helix–coil transition could be found. The association phenomena were discussed on the basis of a rodlike model of polyelectrolyte.