Abstract: | Far-infrared spectra in the region from 700 to 60 cm?1 have been measured for the α-helix structures of poly(L -α-amino-n-butyric acid), poly-L -norvaline, poly-L -norleucine, and poly-L -leucine and for the β-form structures of poly(L -α-amino-n-butyric acid), poly-L -valine, poly(DL -amino-n-butyric acid), poly-DL -norvaline, and poly-DL -norleucine. The changes of the spectra on N-deuteration have been measured in the region between 700 and 400 cm?1. It is concluded that, the α-helix has characteristic bauds near 690, 650, 610, 380, 150, and 100 cm?1, and that the β-form has characteristic bands near 700, 240, and 120 cm?1. The main-chain vibrations in the region from 600 to 200 cm?1 are strongly coupled with the side-chain deformation vibrations. |