DNA Cleavage Activity: Comparison of two Lanthanum Complexes Based on Aza-Crown Ethers with Different Numbers of Nitrogen Atoms

Abstract

Based on the unique characteristics of lanthanum ion and aza-crown ethers, the lanthanum complexes of two aza-crown ether (L1: 1,10-Dioxa-4,7,13,16-tetraazacyclo-octadecane and L2: 1,4,10,13-tetraoxa-7,16-diazacyclooctadecane) were designed and synthesised. The interaction between these two complexes and DNA was measured by UV-Vis spectroscopy and gel electrophoresis. Moreover, a series of experiments of cleavage of pUC19 DNA were conducted to illustrate the acidity, time and concentration effects. The results indicated that the two metal complexes can accelerate the breakage of DNA from its supercoiled form (form I) to the nicked form (form II) at near-physiological conditions, and the optimum acidity of DNA catalytic cleavage is pH=6.5 and pH=7.0 for LaL1 and LaL2, respectively. Furthermore, the LaL1 exhibited better cleavage activity than LaL2 under the same conditions, thus supercoiled DNA was thoroughly cleaved to the nicked form under the appropriate conditions. The hydrolytic mechanism was verified by applying several oxygen-scavengers to the DNA catalytic cleavage.

Nuclease Activity of Diaza-Crown Ether Complexes of Cerium(III) with Different Functional Groups as Side Arms

“…DNA cleavage was analysed by gel electrophoresis using a DYY-12 electrophoresis power supply (Beijing) and gel image analysing system (Vilber Lourmat BIO-1D, France). 1,4,10,13-Tetraoxa-7,16-diazacyclooctadecane (L 0 ), as the parent ligand, was synthesised by our research group [25]. Tris(hydroxymethyl)aminomethane (Tris), chloroacetamide, triethylamine, ethanol, Ce(NO 3 ) 3 .6H 2 O, triethyl orthoformate, HCl, NaOH and NaCl were purchased from Chongqing Chemical Co. Plasmid pUC19 DNA, 50 × TAE buffer, 6 × loading buffer, goldview dye and agarose were purchased from Beijing Dingguo Changsheng Biotechnology Co. Ltd. All other chemicals purchased from Chongqing chemical Co., unless otherwise indicated, were of analytical grade.…”