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Helix–coil transition of poly-γ-N-carbobenzoxy-L-α,γ-diaminobutyrate and poly-δ-N-carbobenzoxy-L-ornithine

✍ Scribed by Felicia Gaskin; Jen Tsi Yang

Publisher
Wiley (John Wiley & Sons)
Year
1971
Tongue
English
Weight
761 KB
Volume
10
Category
Article
ISSN
0006-3525

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✦ Synopsis

Abstract

The helix–coil transition of poly‐γ‐N‐carbobenzoxy‐L‐α,γ‐diaminobutyrate (PCLB) and poly‐δ‐N‐carbobenzoxy‐L‐ornithine (PCLO) in chloroform–dichloroacetic acid mixtures was followed by optical rotatory dispersion. PCLB displays a “normal” temperature‐induced transition, but PCLO an “inverse” one. The thermodynamic parameters for helix formation of the two polymers were determined using the Zimm‐Bragg theory. The enthalpy for adding an amide residue to a helical region, Δ__H__, and the initiation factor σ were Δ__H__ = −180 cal/mole and σ = 9.2 × 10^−5^ for PCLB and Δ__H__ = +490 cal/mole and σ = 1.9 × 10^−5^ for PCLO.

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