The spectral properties of DNA and RNA macromolecules at low temperatures: fundamental and applied aspects

Abstract

This paper summarizes the results of studies of the spectral properties-optical absorption, fluorescence and phosphorescence-of DNA and RNA macromolecules and synthetic poly-, oligo- and mono-nucleotides, which have been carried out in our laboratory. The system of first excited singlet and triplet energy levels for DNA and RNA is evaluated using low-temperature (4.2 K-77 K) luminescent measurements. The traps of the singlet and triplet electronic excitations in these compounds are identified. An important self-protection mechanism against photo-damage of DNA and RNA by UV photons or penetrative radiation based on the capture of triplet electronic-energy excitations by the most photostable centers-in DNA, the complex formed by neighboring adenosine (A) and thymidine (T) links; in RNA, the adenosine links-is described. It is confirmed that despite similarities in the chemical and partly energy structures DNA is more stable than RNA. The spectral manifestation of the telomeres (the important functional system) in DNA macromolecules is examined. The results obtained on telomere fragments provide the possibility of finding the configuration peculiarities of the triplet excitations traps in DNA macromolecules. The resulting spreading length of the migrating singlet (l ) and triplet (l) excitations for DNA and RNA macromolecules are evaluated.

Spectral Properties of Single-Stranded Viral DNA Fragment

“…The fluorescence spectral bands of (-)PBS and (+)PBS at = 78 K (Fig. 2) are close to each other, as well as to the band of oligunucleotide Tel-22 investigated by us earlier [5][6][7]. They do not co- Fig.…”

“…The difference between (-)PBS/ (+)PBS and dAMP phosphorescence spectra (the band at = 530 nm) is thought to be associated with an unknown center, possibly, G-complex or G-intermediate that dominates in the fluorescence. Thus, the main centers of triplet excitation capturing in (-)PBS and (+)PBS oligonucleotides are A-bases and some centers of an unknown nature (possibly, G-complexes or G-intermediates, but they are not AT-complexes observed by us in [3][4][5][6][7]). The "1-3-difference" band was obtained by the subtraction of the dAMP spectral band from the (-)PBS spectral band.…”

“…The first main goal of our investigations is the identification of the absorbing, fluorescent and phosphorescent centers in (-)PBS and (+)PBS. On the other hand, it is known [3][4][5][6][7] that the capturing centers of the triplet excitation in DNA are AT-sequences. Recently, we showed that this AT-complex is formed by neighbor A-and T-chromophores from the same strand (not from A-and T-complementary chromophores of the different strands) [5][6][7].…”

Fluorescence research in Ukraine

“…Terentyeva, Yashchuk et al have investigated intrinsic luminescence of leukocytes [29], DNA and RNA [30]. Auto-absorption, auto-fluorescence and auto-phosphorescence spectra of leukocytes and individual organelles are applied to differentiate between the normal and abnormal cells [29].…”

“…Auto-absorption, auto-fluorescence and auto-phosphorescence spectra of leukocytes and individual organelles are applied to differentiate between the normal and abnormal cells [29]. The authors have attempted to correlate the intrinsic absorption and luminescence of DNA, telomers and RNA with stability and self-protection of the nucleic acids [30].…”