Low-frequency, Raman-active vibrational modes of poly(dA)<i>⋅</i>poly(dT)

Abstract

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