Characteristics of the interaction of lycobetaine with DNA.

The characteristics of the interaction of lycobetaine (LBT) with DNA were examined by fluorescence spectrometer, disc electrophoresis and restriction enzyme analysis. The apparent binding constant of LBT with calf thymus DNA has been determined as 1.67 x 10(6) L/mol by ethidium bromide displacement method. Based on electrophoresis titration, the mode of DNA binding was found to be through intercalation. Fluorescence quenching assay showed that the intrinsic association constant and the binding site size of LBT to calf thymus DNA were 0.26 x 10(6) L/mol and 2.6 base pairs, respectively. Selective inhibition of LBT on action of some restriction enzymes showed that LBT intercalate preferentially into GC base pairs. Neither DNA strand break nor interstrand cross-link was produced by LBT. LBT did not bind to DNA covalently and did not cause DNA alkylation.