[Studies on the interaction mode between polymyxin B sulfate and DNA with EB as a fluorescence probe].

The interaction between polymyxin B sulfate and ct-DNA was studied with ethidium bromide (EB) probe by UV spectroscopy, fluorescence spectroscopy, fluorescent polarization etc. The phenomena of hyperchromism effect and fluorescence quenching proved that polymyxin B sulfate in buffer solution at pH 7.4 can intercalate into the base pairs of ct-DNA. This interaction can cause conformational change of ct-DNA double helix. This interaction can be inhibited in the presence of high concentration of ions. At the same time, PB can combine with the phosphate group of ct-DNA by non-characteristic static force. In this paper, the interaction of PB and ct-DNA was made further discussion.