Factors Influencing the DNA Nuclease Activity of Iron, Cobalt, Nickel, and Copper Chelates

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• 作者：Jeff C. Joyner ; Jared Reichfield ; J. A. Cowan
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：October 5, 2011
• 年：2011
• 卷：133
• 期：39
• 页码：15613-15626
• 全文大小：1183K
• 年卷期：v.133,no.39(October 5, 2011)
• ISSN：1520-5126

文摘

A library of complexes that included iron, cobalt, nickel, and copper chelates of cyclam, cyclen, DOTA, DTPA, EDTA, tripeptide GGH, tetrapeptide KGHK, NTA, and TACN was evaluated for DNA nuclease activity, ascorbate consumption, superoxide and hydroxyl radical generation, and reduction potential under physiologically relevant conditions. Plasmid DNA cleavage rates demonstrated by combinations of each complex and biological co-reactants were quantified by gel electrophoresis, yielding second-order rate constants for DNA_supercoiled to DNA_nicked conversion up to 2.5 脳 10⁶ M^鈥? min^鈥?, and for DNA_nicked to DNA_linear up to 7 脳 10⁵ M^鈥? min^鈥?. Relative rates of radical generation and characterization of radical species were determined by reaction with the fluorescent radical probes TEMPO-9-AC and rhodamine B. Ascorbate turnover rate constants ranging from 3 脳 10^鈥? to 0.13 min^鈥? were determined, although many complexes demonstrated no measurable activity. Inhibition and Freifelder鈥揟rumbo analysis of DNA cleavage supported concerted cleavage of dsDNA by a metal-associated reactive oxygen species (ROS) in the case of Cu²⁺(aq), Cu-KGHK, Co-KGHK, and Cu-NTA and stepwise cleavage for Fe²⁺(aq), Cu-cyclam, Cu-cyclen, Co-cyclen, Cu-EDTA, Ni-EDTA, Co-EDTA, Cu-GGH, and Co-NTA. Reduction potentials varied over the range from 鈭?62 to +1111 mV versus NHE, and complexes demonstrated optimal catalytic activity in the range of the physiological redox co-reactants ascorbate and peroxide (鈭?6 to +380 mV).