Cusumano Matteo, Di Pietro Maria Letizia, Giannetto Antonino, Nicolò Francesco, Rotondo Enrico
Dipartimento di Chimica Inorganica, Chimica Analitica e Chimica Fisica, University of Messina, Messina, Italy.
Inorg Chem. 1998 Feb 9;37(3):563-568. doi: 10.1021/ic9705406.
The interaction of the complexes Pt(bipy)(4-Rpy)(2) and Pt(4,4'-Ph(2)bipy)(4-Rpy)(2) (Ph = phenyl; bipy = 2,2'-bipyridine; R = H, CN, CH(3), NH(2)) with DNA has been studied with a series of techniques. The processes give rise to (i) lengthening of rodlike DNA and unwinding of closed circular DNA and (ii) an increase in the DNA melting temperature comparable with that observed for known intercalators. In addition, the reaction of the complexes Pt(bipy)(py)(2) and Pt(4,4'-Ph(2)bipy)(py)(2) is inhibited by the presence of DNA. These results have been interpreted by assuming that the substances intercalate in spite of the presence of ligands out of plane. The crystal structure determined for Pt(4,4'-Ph(2)bipy)(3,5-Me(2)py)(2) by X-ray analysis shows that also one of the phenyl rings is twisted with respect to the square plane. Binding constants, K(B), determined spectrophotometrically at 25 degrees C and pH 7 using the McGhee-von Hippel approach, increase for both series of complexes on increasing pK(a) of coordinated pyridines and are larger for those with 4,4'-Ph(2)bipy. The increasing affinity for DNA on increasing electron density of the interacting moiety is accounted for by assuming that London dispersion forces play a major role in the processes.
已使用一系列技术研究了配合物Pt(bipy)(4-Rpy)(2)和Pt(4,4'-Ph(2)bipy)(4-Rpy)(2)（Ph = 苯基；bipy = 2,2'-联吡啶；R = H、CN、CH(3)、NH(2)）与DNA的相互作用。这些过程导致（i）棒状DNA延长和闭环DNA解旋，以及（ii）DNA解链温度升高，这与已知嵌入剂所观察到的情况相当。此外，配合物Pt(bipy)(py)(2)和Pt(4,4'-Ph(2)bipy)(py)(2)的反应会受到DNA的抑制。这些结果的解释是，尽管存在平面外配体，但这些物质仍会嵌入。通过X射线分析确定的Pt(4,4'-Ph(2)bipy)(3,5-Me(2)py)(2)的晶体结构表明，其中一个苯环也相对于正方形平面发生了扭曲。使用McGhee-von Hippel方法在25℃和pH 7下通过分光光度法测定的结合常数K(B)，对于这两个系列的配合物，随着配位吡啶的pK(a)增加而增大，并且对于含有4,4'-Ph(2)bipy的配合物更大。通过假设伦敦色散力在这些过程中起主要作用，可以解释相互作用部分电子密度增加时对DNA亲和力的增加。
