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Spectroscopic studies of random chain and α‐helical polypeptides in hexafluoroisopropanol
Author(s) -
Parrish Joseph R.,
Blout Elkan R.
Publication year - 1971
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.360100906
Subject(s) - optical rotatory dispersion , circular dichroism , chemistry , vibrational circular dichroism , solvent , crystallography , cotton effect , spectral line , ionic bonding , ultraviolet , methionine , stereochemistry , amino acid , organic chemistry , biochemistry , materials science , ion , physics , optoelectronics , astronomy
The infrared, ultraviolet, circular dichroism, and optical rotatory dispersion spectra of five synthetic polypeptides dissolved in hexafluoroisopropanol are reported. This solvent is useful because it dissolves most proteins and non‐ionic polypeptides and also is transparent in spectral regions critical for polypeptide conformational diagnoses. Poly‐γ‐morpholinylethyl‐ L ‐glutamamide has random chain type spectra in this solvent, whereas the spectra of poly‐γ‐methyl‐ L ‐glutamate, poly‐ L ‐methionine, poly‐ε, N ‐Carbo‐benzoxy‐ L ‐lysine, and poly‐ L ‐homoserine indicate that these four polypeptides are α‐helical. Small but significant variability between the different α‐helical polypeptides is seen in their circular dichroism spectra and optical rotatory dispersions. An argument is presented that these differences may be due to slight geometry differences between different α‐helices.