Enantioselective binding of S- and R-ofloxacin to various synthetic polynucleotides.

The binding properties of S- and R-ofloxacin to poly[d(A-T)(2)], poly[d(G-C)(2)] and poly[d(I-C)(2)] were studied by circular dichroism (CD) and various fluorescence techniques. The spectral properties of R-ofloxacin did not change when it was mixed with poly[d(A-T)(2)] and poly[d(I-C)(2)], indicating that R-enantiomer does not interact with these polynucleotides. On the other hand, when S-ofloxacin was mixed with any polynucleotide, or R-enantiomer with poly[d(G-C)(2)], characteristic changes in CD and fluorescence were observed. Therefore, it is clear that enantiomers of ofloxacin selectively recognize B-form DNA. The overall spectral properties of the ofloxacin-polynucleotide complex are similar to those of the norfloxacin-polynucleotide complex [Eur. J. Biochem. 267 (2000) 6018], suggesting that this quinolone also binds in the minor groove of DNA and therefore it may be partially inserted between DNA bases or interact with purine bases.