Effect of Premelting on Conductivity of DNA-Lipid Films
Figure 4
Temperature-dependent premelting effect in Raman frequencies of (a) the
admixture of complex vibration of the B-DNA phosphodiester backbone conformation
and thymine and cytosine ring modes [18], (b) dT C-endo sugar pucker
and anti glycosyl torsion mode [8], and (c) dG and dA ring stretching
vibrations sensitive to hydrogen bonding [18, 19] as well as dT [10]. The bands
shift toward lower frequencies starting near 35°C and the movement attenuates
for 65°C and higher for phosphodiester geometry and deoxyribose hydrogen bond
vibrations. The onset of premelting effect at 746 c occurs near 50°C. (d) Interbase hydrogen bonding. The bands returns to their
original position once the film is cooled back down to room temperature (see
blue triangles in panels (a) and (b)). inset b: The intensity change near 1660–1680 c is observable from
35°C and higher with no sign of attenuation. The spectra are normalized to the
intensity values at 1664 c in order to show the
relative intensity change among three bands (indicated by 3 arrows). The
continued enhancement of 1680 c from room
temperature to 80°C is clearly observed. The bands at 1664 and 1650 c are indistinguishable at 20°C (thick line), and separate themselves into two
distinct peaks at 1664 and 1648 c at 80°C
(thin line).
