The dynamics of (57)Fe nuclei in Fe(III)-DNA condensates.

The dynamics of iron nuclei in the condensates obtained by interaction of Fe(III) with DNA, Fe(III)(DNA monomer)(2), have been investigated by variable temperature (57)Fe M?ssbauer spectroscopy. Studies were effected on gel and freeze-dried samples, obtaining nearly coincident values of the parameters isomer shift and nuclear quadrupole splitting in T ranges 20-260 K. Functions ln(A(T)/A(77.3)) vs. T, here employed to investigate the dynamics of Fe nuclei, showed linear trends in the T ranges 20-150 and 150-260 K, respectively, the latter with larger slopes. Data coincided for gelled and freeze-dried specimens. No variation of delta or Delta E parameters occurred at the two T intervals, which suggests constancy of structure and bonding with the temperature changes. Functions (T) showed trends analogous to the corresponding functions determined for iron proteins, which were attributed to the occurrence of 'conformational substates'.