Spectroscopic studies on the interaction between Pr(III) complex of an ofloxacin derivative and bovine serum albumin or DNA
作者:Min Xu、Zhao-Rong Ma、Liang Huang、Feng-Juan Chen、Zheng-zhi Zeng
DOI:10.1016/j.saa.2010.11.018
日期:2011.1
The binding properties on [PrL2(NO3)](NO3)(2) (L=9-fluoro-2,3-dihydro-3-methyl-10-(4-methyl-1-piperaziny)-7-oxo-7Hpyrido[1,2,3-de]-1,4-benzoxazine-6-carbaldehyde benzoyl hydrazone) to bovine serum albumin (BSA) have been studied for the first time using fluorescence spectroscopy in combination with UV-Vis absorbance spectroscopy. The results showed that [PrL2(NO3)](NO3)(2) strongly quenched the intrinsic fluorescence of BSA through a static quenching procedure, and non-radiation energy transfer happened within molecules. The number of binding site was about 1, and the efficiency of Forster energy transfer provided a distance of 4.26 nm between tryptophan and [PrL2(NO3)](NO3)(2) binding site. At 288, 298, 310K, the quenching constants of BSA-(PrL2(NO3)](NO3)(2) system were 5.11 x 10(4), 4.33 x 10(4) and 3.71 x 10(4) IM-1. Delta H, Delta S and Delta G were obtained based on the quenching constants and thermodynamic theory (Delta H < 0, Delta S> 0 and Delta G<0). These results indicated that hydrophobic and electrostatic interactions are the mainly binding forces in the [PrL2(NO3)](NO3)(2)-BSA system. In addition, the CD spectra have proved that BSA secondary structure changed in the presence of [PrL2(NO3)](NO3)(2) in aqueous solution. Moreover, the interaction between [PrL2(NO3)](NO3)(2) and calf thymus DNA (CT DNA) was studied by spectroscopy and viscosity measurements, which showed that the binding mode of the [PrL2(NO3)](NO3)(2) with DNA is intercalation. The DNA cleavage results show that in the absence of any reducing agent, the [PrL2(NO3)](NO3)(2) can cleave plasmid pBR322 DNA and its hydrolytic mechanism was demonstrated with hydroxyl radical scavengers and singlet oxygen quenchers. (C) 2010 Elsevier B.V. All rights reserved.