Abstract: We studied the mechanism of interaction and binding con stant between Eu(Ⅲ) complex with methaerylic acid8hydroxyquinoline （Eu(MA)2(hq)） and her ring sperm DNA by using spectroscopic methods, viscosity and thermal denatur ation method of DNA. Results show that the absorption peak has obvious hypochrom ic effect, but red shift phenomenon of peak is not obvious after the complex add ing herring sperm DNA. The complex can quench the fluorescence of neutral redDNA system. The binding ratio of n(Eu(MA)2(hq))∶n(DNA) is 1, and the binding cons tants are K₂₀= 5.91×10³ L/mol, an d K₃₅=7.70×10³ L/mol. The thermodynamic functions between complex and herring sperm DNA are Δr H_m=1.34×10³ J/mol, Δr G_m=-2.12×10⁴ J/mol, and Δr S_m=76.41 J/(mol·K) . The relative viscosity and melting point of herring sperm DNA ar e increased with the addition of complex, and the interaction mode of the Eu(MA)₂ (hq) with herring sperm DNA belongs to intercalation.

Key words: herring sperm, methacrylic acid-8-hydroxyquinoline\, interaction, Eu(Ⅲ), DNA, complex