[IR-spectroscopic study of the temperature anomaly of water sorbed onto DNA]

IR-spectra of liquid water and that sorbed on native and denaturated DNA at different relative humidity (RH) are obtained in the region of valent OH-(OD)-oscillations within the temperature range 0--100 degrees C. An S-shape decrease of absorption intensity was observed for water sorbed on DNA at 94% RH in two temperature regions (25--45 and 75--95 degrees C). Proceeding from the assumption that individual absorption bands are described by equal symmetrical functions, development of complex absorption contour of D2O in the region 3000--2000 cm-1 into constituents was performed. It enabled to determine band parameters of underphase vuf and synphase vsf valent and overtone of deformation oscillations of OD-groups in liquid and sorbed water and to reveal at higher temperatures the bands of "free" OD-groups (v = 2668 cm-1). Relative contribution of integral intensity of the latter at 96 degrees C in sorbed water is about 4 times lower than in the liquid one.