H-1-NMR DETERMINATION OF THE THERMODYNAMICS OF DRUG COMPLEXATION WITHSINGLE-STRANDED AND DOUBLE-STRANDED OLIGONUCLEOTIDES IN SOLUTION - ETHIDIUM-BROMIDE COMPLEXATION WITH THE DEOXYTETRANUCLEOTIDES 5'-D(APCPGPT), 5'-D(APGPCPT), AND 5'-D(TPGPCPA)
Db. Davies et al., H-1-NMR DETERMINATION OF THE THERMODYNAMICS OF DRUG COMPLEXATION WITHSINGLE-STRANDED AND DOUBLE-STRANDED OLIGONUCLEOTIDES IN SOLUTION - ETHIDIUM-BROMIDE COMPLEXATION WITH THE DEOXYTETRANUCLEOTIDES 5'-D(APCPGPT), 5'-D(APGPCPT), AND 5'-D(TPGPCPA), Biopolymers, 42(3), 1997, pp. 285-295
The thermodynamical parameters (free energy, enthalpy, and entropy) of
complex formation between ethidium bromide and single-stranded and do
uble-stranded tetranucleotides of different base sequence [5'-d(TpGpCp
A), 5'-d(ApCpGpT), and 5'-d(ApGpCpT)] have been determined from the te
mperature dependencies of 500 MHz proton nmr chemical shifts. The anal
ysis enables the contributions to be differentiated for the formation
of different types of complexes (1:1, 2:1, 1:2, and 2:2) in aqueous so
lution. The results have been interpreted in terms of the main types o
f intermolecular interactions responsible for formation of the differe
nt complexes; van der Waals and electrostatic interactions are importa
nt for formation of complexes of ethidium bromide with single-stranded
tetranucleotides, whereas van der Waals and hydrophobic interactions
play a significant role in the binding of the dye to the tetramer dupl
exes. (C) 1997 John Wiley & Sons, Inc.