Raman spectra of copoly(D,L-alanines)

✍ Scribed by Koichi Itoh; Tetsu Hinomoto; Takehiko Shimanouchi

• Publisher: Wiley (John Wiley & Sons)
• Year: 1974
• Tongue: English
• Weight: 291 KB
• Volume: 13
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1974.360130206

✦ Synopsis

Abstract

Raman spectra in the region 1000–150 cm^−1^ were measured for copoly(D,L‐alanines) with the D‐residue contents, 3, 7, 10, and 20%, and compared with the spectrum of the α‐helical poly‐L‐alanine. The 532‐ and 378‐cm^−1^ peaks were assigned to the L‐residues with a right‐handed α‐helix‐like local conformation or to the D‐residues with a left‐handed α‐helix‐like local conformation. From the intensity of the latter peak the contents of these local conformations were estimated as a function of the D‐residue contents for the copolymers. The 264‐cm^−1^ peak, which has been assigned to the breathing vibration of the α‐helical poly‐L‐alanine, shows a marked decrease in its intensity upon the introduction of the D residues. This result suggests that the overall deformation vibration of the α‐helix arises from rather long sequences of the L‐ and D‐alanine residues with the α‐helical conformation and that the intensity of this vibration depends on the content of these sequences in the copolymers.