Mirabelli C K, Zimmerman J P, Bartus H R, Sung C M, Crooke S T
Biochem Pharmacol. 1986 May 1;35(9):1435-43. doi: 10.1016/0006-2952(86)90107-3.
The ability of gold coordination complexes to bind to DNA and produce inter-strand cross-links in DNA was assessed in an assay system based on the fluorescence properties of the DNA intercalative dye, ethidium bromide. Results from these studies using a variety of gold(I) and gold(III) complexes suggest that the ability of gold complexes to bind to and produce inter-strand cross-links in DNA is not dependent on the oxidation state of gold in the complex but is influenced by the nature of the coordinating ligands. Those complexes in which the gold was ligated through one or more weakly coordinating ligands showed evidence for DNA binding. However, only those complexes with two or more of these relatively weak coordinating ligands produced inter-strand cross-links. Both the amount of binding to and cross-linking of DNA by these compounds were decreased by treatment of the gold-DNA complex with 2-mercaptoethanol and other thiol containing agents. As shown by agarose gel electrophoresis, 2-mercaptoethanol caused a dissociation of the gold-DNA complexes and a regeneration of closed circular superhelical pBR322 DNA. DNA strand breakage also resulted from treatment of a number of gold-DNA complexes with 2-mercaptoethanol; this was observed with the gold compounds which were shown to produce inter-strand cross-links in DNA. The amount of DNA strand breakage produced by treatment of gold-DNA complexes with 2-mercaptoethanol was influenced by the initial conformation of the DNA; gold-DNA complexes which resulted from the binding of gold compounds to covalently closed superhelical DNA were more sensitive to the breakage induced by 2-mercaptoethanol treatment than those complexes in which closed circular, relaxed DNA was used as substrate. The DNA breakage was not reduced in partially anaerobic conditions or by free-radical scavengers, suggesting that it is not mediated by oxygen. The results are discussed with respect to the potential for the interaction of gold complexes with intracellular DNA and chromatin and their biological implications.
基于DNA嵌入染料溴化乙锭的荧光特性，在一个检测系统中评估了金配位络合物与DNA结合并在DNA中产生链间交联的能力。使用多种金（I）和金（III）络合物进行的这些研究结果表明，金络合物与DNA结合并在DNA中产生链间交联的能力并不取决于络合物中金的氧化态，而是受配位配体性质的影响。那些通过一个或多个弱配位配体连接金的络合物显示出与DNA结合的证据。然而，只有那些含有两个或更多这些相对较弱配位配体的络合物才会产生链间交联。用2-巯基乙醇和其他含硫醇试剂处理金-DNA络合物会降低这些化合物与DNA的结合量和交联量。如琼脂糖凝胶电泳所示，2-巯基乙醇导致金-DNA络合物解离，并使闭环超螺旋pBR322 DNA再生。用2-巯基乙醇处理一些金-DNA络合物也会导致DNA链断裂；在用显示能在DNA中产生链间交联的金化合物中观察到了这种情况。用2-巯基乙醇处理金-DNA络合物产生的DNA链断裂量受DNA初始构象的影响；由金化合物与共价闭合超螺旋DNA结合产生的金-DNA络合物比以闭环松弛DNA为底物的那些络合物对2-巯基乙醇处理诱导的断裂更敏感。在部分厌氧条件下或通过自由基清除剂处理，DNA断裂并没有减少，这表明它不是由氧气介导的。讨论了这些结果与金络合物与细胞内DNA和染色质相互作用的可能性及其生物学意义。
