  The aim of the present work is spectroscopic and thermodynamic study of DNA
catalytic properties in the following processes: a) redox; b) formation of
inter-strand cross-links; c) performing of photo-dynamic effects; d) nanoscale
resonance radiationless electron excitation energy transfer. The most attention
is paid to the latter, as truly nanoscale method in its origin. The nanoscale
method of laser induced fluorescence resonance energy transfer (FRET) to donor
(acridine orange) - acceptor (ethidium bromide) intercalator pair for
quantitative and qualitative study of stability quality DNA double helix in
solution in real time is offered. FRET method allows to estimate the
concentration of double helix areas with high quality stability applicable for
intercalation in DNA after it was subjected to stress effect. It gives the
opportunity to compare various types of DNAs with 1) different origin; 2)
various damage degrees; 3) being in various functional state. Alternative model
and mechanisms of photodynamic effect on DNA in solutions are proposed. They
are based on photoenergy degradation in solutions. The energy activates
electrolytic dissociation of water molecules on H3O+ and OH- and acts as a
catalyst for hydrolyse reactions of phosphordiester and glycoside linkages.
