Chemical Research in Chinese Universities ›› 2009, Vol. 25 ›› Issue (4): 492-496.

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Characterization of DNA Intercalator Bound to Calf Thymus DNA: Ionic Strength and pH Value Effects

YUAN Chun-li1, ZHANG Zhi-chao2*, SONG Ting2 and WU Gui-ye2   

  1. 1. Department of Gynecology and Obstetrics, First Hospital of Jilin University, Changchun 130021, P. R. China;
    2. State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116012, P. R. China
  • Received:2008-06-26 Revised:2009-01-05 Online:2009-07-25 Published:2009-10-16
  • Contact: ZHANG Zhi-chao. E-mail: zczhang@dcut.edu.cn
  • Supported by:

    Supported by National Natural Science Foundation of China(No.30772622).

Abstract:

By means of circular dichroism(CD) spectrum coupled with UV-Vis and fluorescence spectra, the binding model of DNA intercalator A1{4-(2-diethylamino-ethylamino)-8-oxo-8H-acenaphtho[1,2-b]pyrrole-9-carbonitrile} to calf thymus(CT) DNA was investigated, depending on the values of R(R is defined as the ratio of the concentration of A1 to CT DNA base pairs) and different outer factors. Molecules A1 were intercalated into the CT DNA base pairs in different orientations in the intercalation pocket at a lower R value(R≤0.20), while A1 molecules aggregated on the surface of the helix of the CT DNA as the R value increased. The influence of NaCl on the binding was smaller because the electrostatic interaction only provided approximately 16% of the overall free energy of binding. The protonated diethyl-amine substitution would influence the binding geometry greatly at a low pH value via forming hydrogen bonds with the exposed C=O group on DNA surface.

Key words: DNA intercalator; 4-(2-Diethylamino-ethylamino)-8-oxo-8H-acenaphtho[1,2-b]pyrrole-9-carbonitrile; Ionic strength