| Abstract: The chemical nuclease activities of three closely related Schiff base tetraazamacrocyclic oxamido copper(Ⅱ) complexes (CuL1～3）were compared and the result shows that their chemical nuclease activities follow the order of CuL3＞CuL2＞CuL1. Where complexes CuL1～3 are[5,6-d][13,14-d]dibenzo-1,4,8,11 -tetraazacyclotetradecane-dione-2,3-diene-7,11-di-ethylcarboxylate-7,12 Copper(Ⅱ), [5,6-d][13,14-d]dibenzo-10-methyl-1,4,8,11-tetraazacyclo-tetradecane-dione-2,3-diene-7,11-di-ethylcarboxylate-7,12 Copper(Ⅱ) and[5,6-d][13,14-d]dibenzo-[9,10-d] -cyclehexano-1,4,8,11-tetraazacyclotetradecane-dione-2,3-diene-7,11-di-ethylcarboxylate-7,12 Copper(Ⅱ), respectiv-ely. The interactions of CuL3 with DNA were studied in detail, and the results show that the chemical nuclease activity of this complex is affected by central metal ions, structure of ligands, pH value, ion strength and complex concentration. DNA cleavage reaction in presence of the copper(Ⅱ) complexes is a typical pesudo-first-order consecutive reaction, and the rate constants of 0.044 0±0.001 5 min-1(k1) and 0.003 52±0.000 18 min-1(k2) for the conversion of supercoiled to nicked DNA and nicked to linear DNA are obtained in presence of 80 μmol·L-1 CuL3 and 2 mmol·L-1 H2O2, respectively. |
