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Solution properties of synthetic polypeptides. XVII. Stability of the α-helical conformation of poly(γ-benzyl L-glutamate) in helicogenic solvents

✍ Scribed by Tadao Matsumoto; Akio Teramoto

Publisher
Wiley (John Wiley & Sons)
Year
1974
Tongue
English
Weight
567 KB
Volume
13
Category
Article
ISSN
0006-3525

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✦ Synopsis

Abstract

The Zimm–Bragg parameters s and σ were determined for poly(γ‐benzyl L‐glutamate) (PBLG) in m‐cresol and in dimethylformamide (DMF) from ORD data as a function of molecular weight. It was found that, within the temperature range between 10 and 55°C and on the average, s = 1.6~1~ ± 0.1 and √σ = 0.04 ± 0.01 in m‐cresol and s = 1.6~5~ ± 0.05 and √σ = 0.045 ± 0.015 in DMF. The values of s in m‐cresol decreased with increasing temperature, while the values of σ in the same solvent increased. This result for s suggests that PBLG in m‐cresol will undergo a thermal helix–coil transition of normal type. The parameters in DMF showed no appreciable trend to vary with temperature. Aside from the difference between the two solvents, our results are consistent with existing data for various conformation‐dependent properties such as light‐scattering radius, intrinsic viscosity, and dipole moment, each indicating that the polypeptide chain has some flexibility in helicogenic solvents.

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