Spectroscopic Studies of DNA Interactions with Food Colorant Indigo Carmine with the Use of Ethidium Bromide as a Fluorescence Probe
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- 作者：Yadi Ma ; Guowen Zhang ; Junhui Pan
- 刊名：Journal of Agricultural and Food Chemistry
- 出版年：2012
- 出版时间：October 31, 2012
- 年：2012
- 卷：60
- 期：43
- 页码：10867-10875
- 全文大小：414K
- 年卷期：v.60,no.43(October 31, 2012)
- ISSN：1520-5118
文摘
The interaction of indigo carmine (IC) with calf thymus DNA in physiological buffer (pH 7.4), using ethidium bromide (EB) dye as a fluorescence probe, was investigated by ultraviolet鈥搗isible absorption, fluorescence, and circular dichroism (CD) spectroscopy, coupled with viscosity measurements and DNA-melting studies. Hypochromicity of the absorption spectra of IC and enhancement in fluorescence polarization of IC were observed with the addition of DNA. Moreover, the binding of IC to DNA was able to decrease iodide and single-stranded DNA (ssDNA) quenching effects, increase the melting temperature and relative viscosity of DNA, and induce the changes in CD spectra of DNA. All of the evidence indicated that IC interacted with DNA in the mode of intercalative binding. Furthermore, the three-way synchronous fluorescence spectra data obtained from the interaction between IC and DNA鈥揈B were resolved by parallel factor analysis (PARAFAC), and the results provided simultaneously the concentration information and the pure spectra for the three reaction components (IC, EB, and DNA鈥揈B) of the system at equilibrium. This PARAFAC demonstrated that the intercalation of IC molecules into DNA proceeded by substituting for EB in the DNA鈥揈B complex. The calculated thermodynamic parameters, 螖H掳 and 螖S掳, suggested that both hydrophobic interactions and hydrogen bonds played a predominant role in the binding of IC to DNA.