The interactions of bis-phenanthridinium-nucleobase conjugates with nucleotides: adenine-conjugate recognizes UMP in aqueous medium

Among series of novel bis-phenanthridinium-nucleobase conjugates, the adenine derivative revealed high (log Ks=6.9 M−1) and selective affinity toward complementary nucleotide (UMP), accompanied by specific change in the UV-vis spectrum of phenanthridine subunits, differing significantly from changes caused by addition of other nucleotides. High stability and selectivity of adenine-conjugate/UMP non-covalent complex is, according to the molecular modeling studies, correlated to the number of inter- and intramolecular aromatic stacking interactions between phenanthridinium subunits, covalently attached adenine and added UMP, while the selectivity of adenine-conjugate toward UMP in respect to other nucleotides is most likely the consequence of additional hydrogen bonding between UMP and adenine.