Vibrational frequencies and modes of α-helix

✍ Scribed by Koichi Itoh; Takehiko Shimanouchi

• Publisher: Wiley (John Wiley & Sons)
• Year: 1970
• Tongue: English
• Weight: 681 KB
• Volume: 9
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.1970.360090402

✦ Synopsis

Abstract

Dichroic properties of the far‐infrared absorption bands of the right‐handed α‐helix of poly‐L‐alanine were measured. The normal vibration frequencies of this structure were calculated. The assignments of bands were made and the vibrational modes dis‐cussed. The frequencies of the α‐helix vibrations with various phase differences were calculated. The frequencies of accordionlike vibrations and Young's modulus of the α‐helix were estimated. The vibrational frequency for the right‐handed α‐helices of poly‐D‐alanine and poly(L‐α‐amino‐n‐butyric acid) were calculated, and the results were used for the interpretation of the spectra of copoly‐D,L‐alanines and poly(L‐α‐amino‐n‐butyric acid). For the latter compound the existence of the rotational isomers in the side chain was strongly suggested. The vibrational modes of the bands characteristic of the α‐helix were discussed with regard to the results of the normal coordinate treatment.