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Helix–coil transition of poly(γ‐benzyl‐ L ‐glutamate) in the dioxane–dichloroacetic acid mixture
Author(s) -
Gupta A. K.,
Dufour C.,
Marchal E.,
Benoit H.
Publication year - 1975
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.1975.360140316
Subject(s) - dichloroacetic acid , chemistry , optical rotatory dispersion , helix (gastropod) , transition (genetics) , enthalpy , organic chemistry , crystallography , circular dichroism , thermodynamics , biochemistry , physics , ecology , snail , gene , biology
The thermal helix–coil transition of four samples of poly(γ‐benzyl‐ L ‐glutamate) in the dioxane–dichloroacetic acid (DCA) mixture was studied by optical rotatory dispersion method. The transition occurred at very high DCA content (97.5% by weight) in this system. The transition parameters have been evaluated by two methods based on the theories of Zimm and Bragg and of Nagai. The values of the helix initiation parameter and of the enthalpy of transition were found to be (4.4 ± 0.4) × 10 −5 and 340 cal/mole, respectively. The range of validity and equivalence of the two methods is discussed.