Structural effects of cobalt-amine compounds on DNA condensation
Structural effects of cobalt-amine compounds on DNA condensation
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DOI：
10.1016/s0006-3495(99)77003-7
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发表时间：
1999-09-01
影响因子：
3.4
通讯作者：
Bloomfield, VA
中科院分区：
文献类型：
--
作者：
Deng, H;Bloomfield, VA
光散射和电子显微镜已被用来研究三价络合物六氨合氯化钴（III）（Cohex），三（乙二胺）氯化钴（III）（Coen）和氯化钴（III）sepulchrate（Cosep）对DNA缩合的结构效应。这些钴胺化合物具有相似的配体配位几何结构，但尺寸略有不同。根据这些配体中亚甲基的数量，它们的疏水性的顺序为Cosep > Coen > Cohex。所有这些化合物在高浓度下都能有效地沉淀DNA;但是尽管表面电荷密度较低，Cosep浓缩DNA的效率是Coen或Cohex的两倍。钴胺/DNA溶液的上清液的UV和CD测量揭示了相对于λ-Coen的Delta-Coen对沉淀的DNA的优先结合，但对Cosep没有手性选择性。竞争实验表明，这三种钴胺化合物与聚集的DNA的结合强度是相当的。DNA缩合需要88-90%的电荷中和。结果表明：1）静电相互作用是多价阳离子与DNA结合的主要驱动力; 2）DNA的缩合依赖于缩合剂的结构; 3）缩合剂表面水分子的水合方式或极化对DNA的缩合和手性识别起着重要作用。
Light scattering and electron microscopy have been used to investigate the structural effects of the trivalent complexes hexaammine cobalt (III) chloride (Cohex), tris(ethylenediamine) cobalt(lll) chloride (Coen), and cobalt(III) sepulchrate chloride (Cosep) on DNA condensation. These cobalt-amine compounds have similar ligand coordination geometries but differ slightly in size. Their hydrophobicity is in the order Cosep > Coen > Cohex, according to the numbers of methylene groups in these ligands. All of these compounds effectively precipitate DNA at high concentrations; but despite a lower surface charge density, Cosep condenses DNA twice as effectively as Coen or Cohex. UV and CD measurements of the supernatants of cobalt-amine/DNA solutions reveal a preferential binding of Delta-Coen over Lambda-Coen to the precipitated DNA, but there is no chiral selectivity for Cosep. Competition experiments show that the binding strengths of these three cobalt-amine compounds to aggregated DNA are comparable. A charge neutralization of 88-90% is required for DNA condensation. Our data indicate that 1) electrostatic interaction is the main driving force for binding of multivalent cations to DNA; 2) DNA condensation is dependent on the structure of the condensing agent; and 3) the hydration pattern or polarization of water molecules on the surface of condensing agents plays an important role in DNA condensation and chiral recognition.