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Specificity in the interaction between poly( L ‐glutamate) and iron (III) complex ions in aqueous solution
Author(s) -
Branca M.,
Marini M. E.,
Pispisa B.
Publication year - 1976
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.1976.360151109
Subject(s) - chemistry , aqueous solution , circular dichroism , counterion , molecule , ion , sodium , crystallography , stereochemistry , organic chemistry
The binding process between sodium poly( L ‐glutamate) and trans ‐2,2′,2″,2‴‐tetrapyridyl‐Fe(III) complex ions in aqueous solution at pH around 7 has been studied by means of equilibrium dialysis and optical measurements. The binding isotherm indicates the occurrence of a cooperative process, whereby bound molecules facilitate the association of additional molecules. According to circular dichroism (CD) data, this effect is coupled with that which sees a conformational change in the charged polypeptide upon progessive binding of complex counterions. All these features are discussed in the light of the structural characteristics of the interacting species. A stereochemical model of the association “complex” is proposed.