Biopolymers and cell. 1998; 14 (1): 43 - 46

Study of the quantitative characteristics of tilorone complexation with polynucleotides of various origin

A. V. Karpov, S. N. Khrapunov, A. V. Sivolob

Thermodynamic parameters of tilorone hydrochloride (dihydro-chloricle salt of 2,7-bisf2-(diethyl-amino)ethoxyJ-fluoren-9-one) binding to nucleic acids are. measured spectrophotometrically. It is found that the binding constants for DNA and poly(U) are 5,3 -10s M'1 and 4,7-l(f M respectively, while the binding site sizes for these polynucleotides are, respectively, about 2 bp and I nucleotidc. The analysis of binding isotherm for native yeast RNA shows that the binding^ constants for double- and single-stranded regions are 1,3-10 M and 1,1-10 M respectively. The fraction of double-stranded regions in the RNA is found to be 32 %, the value which are considerably higher than the value previously reported for the same RNA sample in the absence of tilorone. A tilorone high ability of stabilizing double-stranded RNA regions is suggested and biological applications of this ability, especially for interferon induction, are discussed.