Spectroscopic investigation on the toxic interaction of melamine with herring sperm DNA.

The toxic interaction of melamine with herring sperm DNA (hs-DNA) was investigated by using fluorescence and UV-vis absorption spectra techniques. The experimental results showed that the toxic interaction between melamine and hs-DNA occurred. Fluorescence quenching experiments indicated the existence of electrostatic binding between melamine and hs-DNA. The binding constants K(A) and the binding site numbers were calculated by means of the Stern-Volmer equation and were 9.8 × 10(4) L mol(-1) and 1.3, respectively. Both the results of fluorescence spectra and UV-vis absorption spectra verified that there are electrostatic binding between melamine and hs-DNA. The possibility in the presence of a classical intercalation binding mode could be ruled out by using DNA unwinding experiments.