Intrinsic enantioselectivity of natural polynucleotides modulated by copper ions.

Natural polynucleotides including Micrococcus lysodeikticus and calf thymus DNA exhibit enantioselective recognition to S-ofloxacin regulated by Cu(2+). This is the first report that ofloxacin and Cu(2+) have cooperative effects on the local distortions of polynucleotides. At the [Cu(2+)]/[base] ratio of 0.1, S-ofloxacin is more liable to induce the locally distorted structures of polynucleotides, of which the association constant of S-ofloxacin toward DNA-Cu(II) is three times higher than that of the R-enantiomer. The apparent increase of adsorption capability and cooperativity, as well as the change of adsorption mechanism were detected in the adsorption of ofloxacin enantiomers on polynucleotides upon Cu(II)-coordination. This study not only discloses the effect of the chiral drug on the structural transition of long double-stranded DNA, but provides fundamental data to develop a novel enantioseparation method based on natural polynucleotides.
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