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首页> 外文期刊>Biochemistry >7-Aminoactinomycin Binding to DNA Sequences Lacking GpC Sites: A Thermodynamic and Kinetic Study
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7-Aminoactinomycin Binding to DNA Sequences Lacking GpC Sites: A Thermodynamic and Kinetic Study

机译：7-氨基放线菌素结合缺乏GpC位点的DNA序列：热力学和动力学研究。

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摘要

The interaction of 7-aminoactinomycin (7AAMD) with selected DNA sequences (TAGTTA, R5, HP5, and HP1) of different lengths and secondary structures, all containing a 5′-TAGT-3′ block, was studied at an ionic strength of 0.02 M and pH 7.7 by means of fluorescence equilibrium and kinetic (stopped-flow) measurements. Both approaches indicated that the antibiotic binds strongly to both the single-stranded and hairpin (HP1) structures, although the sequences lacked the canonical GpC sites favored by actinomycin. Binding isotherms and initial rate analyses revealed that the binding stoichiometry was 1:1 in all cases. While the single-stranded sequences displayed a simple monoexponential kinetic behavior, the binding of 7AAMD to HP1 at <30 °C was biphasic and could be rationalized in terms of a sequential formation of two isomeric bound forms or alternatively in terms of an ssHP1−hpHP1 equilibrium, with both HP1 forms reacting with 7AAMD. The rates of complex dissociation induced by the detergent SDS were also measured. After correction of the kinetic traces for spurious effects that can be attributed to the SDS, monoexponential traces were obtained, with relaxation times in agreement with the kinetics of complex formation.
机译：以0.02的离子强度研究了7-氨基放线菌素（7AAMD）与不同长度和二级结构的选定DNA序列（TAGTTA，R5，HP5和HP1）的相互作用，这些序列均包含5'-TAGT-3'嵌段M和pH 7.7通过荧光平衡和动力学（停止流）测量。两种方法都表明，抗生素与单链和发夹结构（HP1）都具有很强的结合力，尽管该序列缺少放线菌所偏爱的典型GpC位点。结合等温线和初始速率分析表明，在所有情况下，结合化学计量比均为1：1。虽然单链序列显示出简单的单指数动力学行为，但在<30°C下7AAMD与HP1的结合是双相的，可以通过依次形成两个同分异构的结合形式或通过ssHP1-hpHP1合理化两种HP1形式均与7AAMD反应。还测量了由洗涤剂SDS诱导的复合物解离的速率。在校正了可归因于SDS的寄生效应的动力学迹线后，获得了单指数迹线，其弛豫时间与复合物形成的动力学一致。

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  • 来源
    《Biochemistry》 |2009年第1期|p.173-179|共7页
  • 作者

    Tarita Biver Marcella Venturini Elizabeth A. Jares-Erijman Thomas M. Jovin and Fernando Secco;

  • 作者单位

    Dipartimento di Chimica e Chimica Industriale, Universit di Pisa, Via Risorgimento 35, 56126 Pisa, Italy, Departamento de Qumica Orgnica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria Pabelln II/3, 1428 Buenos Aires, Argentina, and Laboratory of Cellular Dynamics, Max Planck Institute for Biophysical Chemistry, am Fassberg 11, 37077 Gttingen, Germany;

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