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Heat capacity changes at the helix-coil transition of polypeptides in mixed organic solvents

✍ Scribed by K. Jeremic; F.E. Karasz

Publisher
Elsevier Science
Year
1983
Tongue
English
Weight
426 KB
Volume
19
Category
Article
ISSN
0014-3057

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✦ Synopsis

The thermally induced inverse helix-coil transition of poly(7-benzyl-L-glutamate) (PBLG) in dichloroacetic acid/l,3-dichloropropane, dichloroacetic acid/l-chlorobutane and dichloroacetic acid/l-chlorooctane solvent systems was studied using sensitive differential microcalorimetry. A negative heat capacity increment at the transition was observed for all solvent systems. The experimental values of ACp are in reasonable agreement with the values calculated using a recently developed theoretical model. The transition enthalpy for PBLG in the dichloroacetic acid/l-chlorooctane solvent system using very dilute solutions was also determined. No solute concentration dependence in either AHtr or in the transition temperature in the range 0.007-0.05 mol of monomer unit/kg solvent was found.

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