The Interaction and Driving Mechanism of Sb3+and Calf Thymus DNA
Antimony(Sb)is a common pollutant found in the environment in the forms of Sb3+and Sb5+.Sb3+is more toxic than Sb5+and has been shown to cause DNA damage in various organisms.However,the precise binding mode of Sb3+to DNA and the driving mechanism of this binding remain unclear.This study utilized multispectroscopy techniques,such as UV absorption spectroscopy,fluorescence competitive substitution,and circular dichroism analysis,along with molecular dynamics(MD)simulations,to investigate the interaction between Sb3+and DNA.The findings revealed that Sb3+binds to DNA through a groove mode,leading to slight changes in DNA viscosity,denaturation temperature,and structure.The thermodynamic analysis indicated that electrostatic forces primarily drive the binding of Sb3+to DNA.The fluorescence quenching mechanism of the Sb3+-DNA complex was identified as static quenching,with a binding constant of approximately 104 L mol1,significantly higher than that of most alkaline-earth metals.MD simulations confirmed the experimental results,showing stable binding of Sb3+to the G-C base-rich region of the DNA groove,with an average distance of 2.0 Å.Throughout the simulation,electrostatic interactions were present over 98％of the time,the root mean square deviation(RMSD)remained below 3.5 Å,and the secondary protein structural domains of DNA were minimally affected.This study elucidates the direct interaction mechanism of Sb3+with DNA,providing a scientific foundation for understanding its harmful effects and potential inhibition strategies.
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