Low-frequency, Raman-active vibrational modes of poly(dA)⋅poly(dT)

The Raman activity of low-frequency (20–300 ${\mathrm{cm}}^{\mathrm{-}1}$) vibrational modes of dehydrated, oriented fibers of the sodium salts of poly(dA)⋅poly(dT) and random sequenced DNA have been measured. Distinct bands near 60, 75–100, and 125–140 ${\mathrm{cm}}^{\mathrm{-}1}$ are resolved in poly(dA)⋅poly(dT). The Raman activity of the two lowest bands correlate with the previously observed infrared activity of poly(dA)⋅poly(dT). The apparent reduction in spectral line broadening for poly(dA)⋅poly(dT), as demonstrated by this and previous measurements of a number of different polynucleotides, is considered as possible evidence for inhomogeneous line broadening.