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Far‐infrared spectra of polyalanines with α‐helical and β‐form structures
Author(s) -
Itoh K.,
Nakahara T.,
Shimanouchi T.,
Oya M.,
Uno K.,
Iwakura Y.
Publication year - 1968
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.1968.360061211
Subject(s) - fibroin , chemistry , infrared spectroscopy , helix (gastropod) , infrared , crystallography , residue (chemistry) , alanine , circular dichroism , copolymer , spectral line , alpha helix , stereochemistry , silk , amino acid , polymer , materials science , optics , physics , organic chemistry , ecology , biochemistry , astronomy , snail , composite material , biology
Far‐infrared spectra of poly‐ L ‐alanines having the α‐helical conformation and the β‐form structure were measured. The spectra of glycine– L ‐alanine copolymer, silk fibroin, and copoly‐ D , L ‐alanines with different D : L compositions were also measured. In addition to the bands so far reported, four bands at 190, 107, 120, and 90 cm −1 were found for the α‐helix conformation and the two bands at 442 and 247 cm −1 were found for the β form. The 442 cm −1 band consists of the parallel 432 cm −1 and perpendicular 445 cm −1 bands. The 247 cm −1 band is well defined and has strong dichroism parallel to the direction of stretching. These two bands appear also for silk fibroin and glycine– L ‐alanine copolymer. All the far‐infrared bands of copoly‐ D , L ‐alanines can be interpreted as α‐helix bands, the three peaks at 580, 478, and 420 cm −1 being ascribed to the D ‐residue incorporated into the right‐handed α‐helix or to the L ‐residue in the left‐handed α‐helix.