Boudvillain M, Dalbiès R, Aussourd C, Leng M
Centre de Biophysique Moleculaire, CNRS, Orleans, France.
Nucleic Acids Res. 1995 Jul 11;23(13):2381-8. doi: 10.1093/nar/23.13.2381.
The reaction between trans-diamminedichloroplatinum(II) and single-stranded oligonucleotides containing the sequence d(GXG) (X being an adenine, cytosine or thymine residue) yields trans-[Pt(NH3)2[(GXG)-GN7,GN7]] intrastrand cross-links. These cross-links do not prevent the pairing of the platinated oligonucleotides with their complementary strands but they decrease the thermal stability of the duplexes. The thermal stability is not much affected by the chemical nature of the X residue and its complementary base. By gel electrophoresis, it is shown that the trans- [Pt(NH3)2[d(GTG)-GN7,GN7]] cross-link bends the DNA double helix (26 degrees) and unwinds it (45 degrees). The pairing of the platinated oligonucleotides with their complementary strands promotes the rearrangement of the 1,3-intrastrand cross-links into interstrand cross-links. At a given temperature, the nature of the X residue, its complementary base and of the base pairs adjacent to the adducts do not dramatically affect the rate of the reaction. To know whether trans-[Pt(NH3)2[d(GXG)-GN7,GN7]] cross-links do not rearrange in some sequences, the location of these adducts was searched in double-stranded DNA after reaction with trans-diamminedichloroplatinum(II) by means of the 3'-5' exonuclease activity of T4 DNA polymerase. At low level of platination, trans-[Pt(NH3)2[d(GXG)-GN7,GN7]] cross-links were not detected. Monofunctional adducts and interstrand cross-links were mainly formed. These results are discussed in relation with the clinical inefficiency of trans-diamminedichloroplatinum(II).
反式二氯二氨合铂（II）与含有d（GXG）序列（X为腺嘌呤、胞嘧啶或胸腺嘧啶残基）的单链寡核苷酸之间的反应产生反式-[Pt(NH₃)₂[(GXG)-GN₇,GN₇]]链内交联。这些交联并不妨碍铂化寡核苷酸与其互补链的配对，但会降低双链体的热稳定性。热稳定性受X残基及其互补碱基的化学性质影响不大。通过凝胶电泳表明，反式-[Pt(NH₃)₂[d(GTG)-GN₇,GN₇]]交联使DNA双螺旋弯曲（26度）并解旋（45度）。铂化寡核苷酸与其互补链的配对促进了1,3-链内交联重排为链间交联。在给定温度下，X残基的性质、其互补碱基以及与加合物相邻的碱基对不会显著影响反应速率。为了了解反式-[Pt(NH₃)₂[d(GXG)-GN₇,GN₇]]交联在某些序列中是否不会重排，通过T4 DNA聚合酶的３'-５'核酸外切酶活性，在与反式二氯二氨合铂（II）反应后的双链DNA中寻找这些加合物的位置。在低铂化水平下，未检测到反式-[Pt(NH₃)₂[d(GXG)-GN₇,GN₇]]交联。主要形成了单功能加合物和链间交联。结合反式二氯二氨合铂（II）的临床低效性对这些结果进行了讨论。
