https://doi.org/10.1140/epje/i2012-12100-4
Regular Article
Coil-helix transition in poly(L-glutamic acid): Evidence for a 3-state non-cooperative process
Service de Physique de l’Etat Condensé, CEA Saclay, 91191, Gif-sur-Yvette cedex, France
* e-mail: Gilbert.Zalczer@cea.fr
Received:
21
March
2012
Revised:
28
August
2012
Accepted:
14
September
2012
Published online:
11
October
2012
A careful analysis of measurements of circular dichroism of poly(L-glutamic acid) (PGA) shows that the data can be very accurately described by introducing a third state for the PGA configuration, in addition to the helix and coil ones, and considering a simple equilibrium between these three states, without cooperativity. The third state is more conspicuous when high molecular weight polyethyleneglycol (PEG) is added. Excluded-volume effects shown by differences in the presence of short and long PEG chains suggest a direct interaction of PEG and PGA rather than an osmotic effect.
Key words: Soft Matter: Self-organisation and Supramolecular assemblies
© EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg, 2012
