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A potentiometric and CD investigation on the conformational properties of poly ( L ‐ p ‐aminophenylalanine) in aqueous solution
Author(s) -
Peggion E.,
Cosani A.,
Palumbo M.,
Terbojevich M.,
Goodman M.
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.1976.360151110
Subject(s) - potentiometric titration , chemistry , aqueous solution , circular dichroism , polymer , absorption (acoustics) , crystallography , organic chemistry , electrode , physics , acoustics
The conformational properties of poly( L ‐ p ‐aminophenylalanine) have been investigated by potentiometric and circular dichroism (CD) techniques. It has been found that the polymer in the charge‐free state can assume two ordered conformations, depending upon temperature conditions. At room temperature the polymer assumes the right‐handed helical form by described Goodman and Peggion. 1 At temperatures higher than 40°C a new ordered conformation has been found, whose slow rate of formation and ir absorption properties are typical of the β‐structure. The thermodynamic parameters relative to the coil‐β transition, determined by potentiometric titration techniques, revealed that the thermodynamic stability of the β‐structure is mainly due to enthalpic factors. The formation of this structure is unfavored on a kinetic basis.