Abstract: When three dimensional conformations of nucleic acid are studied with NMR methods, EDTA(ethylene diamine tetra-acetic acid) or its sodium salt has to be added in the solution in order to protect the nucleic acids from contamination by some metal ions such as Mg²⁺ . In this paper, the interaction of d(GGTATACC)₂ and EDTAhas been observed in D₂O solution containing 0.05mmol/L DNA and about 5 mmol/L EDTA. Four pairs of NOE cross peaks connecting the acetic proton(δ 3.64) of EDTA with the protons G₁8(δ 7.81), G₁1′(δ 5.65), G₁3′(δ 4.13) and G₁2′(δ 2.54) of d(GGTATACC)₂ observed, suggesting that EDTA may form complex with d(GGTATACC)₂ possibly through hydrogen bond interactions between amino protons in DNA (H₂ of G₁ and H₄ of C₈) and carbonyl oxygen atoms of EDTA. The interaction of d(GGTATACC)₂ and EDTA may account for NOEs between two DNA oligomers, G₁1′(5.65) and C₈6(7.47), G₁1′(5.65) and C₈2′/C₈2″(2.18).

Key words: NOESY, d(GGTATACC)₂, EDTA, Intermolecular interactions