An. Veselkov et al., COMPLEXATION OF ETHIDIUM-BROMIDE WITH SINGLE-STRANDED SELF-NONCOMPLEMENTARY TETRADEOXYNUCLEOTIDE 5'-D(APAPGPC), Molecular biology, 31(2), 1997, pp. 219-227
Complexation of ethidium bromide (3,8-diamino-6-phenyl-5-ethylphenanth
ridine) dye with single-stranded self-noncomplementary tetradeoxynucle
otide 5'-d(ApApGpC) in water-salt solution was studied by one-dimensio
nal (500 MHz) and two-dimensional (600 MHz) H-1 NMR spectroscopy. Chem
ical shift versus concentration experiments were performed at 298 degr
ees K. Various scenarios of complexation were considered; the stabilit
y constants for complexes as well as the limit chemical shifts of prot
on resonances of complexed EthBr were determined. The fractions of com
plexes were analyzed, and the dynamic equilibrium was described in rel
ation to the dye/tetranucleotide concentration ratio. Sequence-specifi
c binding of EthBr to the single-stranded nucleotide was inferred. The
most probable configurations of 1:1 and 2:1 complexes of EthBr with t
he tetradeoxynucleotide were proposed basing on the calculated values
of induced H-1 chemical shifts of the dye and on 2D NOE data.