TIME-DOMAIN REFLECTOMETRY TECHNIQUES USED AS AN ANALYTICAL TOOL TO INVESTIGATE WATER-MOLECULES BOUND TO SOLID-STATE DEOXYRIBONUCLEIC-ACID (DNA)

In this study, the dielectric properties of ion-reduced Na- and Mg-DNA have been investigated over a frequency range 10(5)-10(10) Hz as a fu nction of hydration and temperature, using time domain reflectometry t echniques. Three distinct dispersions have been identified, centred at frequencies of ca. 10(7), 10(8) and 10(10) Hz, respectively. The lowe st frequency dispersion has been attributed to localised relaxation of counter-ions associated with the phosphate groups of the DNA double h elix (G. P. Archer, S. Bone and R. Pethig, J. Mol. Electron., 1990, 6, 199). The highest frequency dispersion is thought to be the result of the rotational relaxation of DNA-bound water molecules. The origin of the dispersion centred in the 10(8) Hz region is discussed in terms o f a number of possible relaxation processes.