Kaspárková J, Mellish K J, Qu Y, Brabec V, Farrell N
Institute of Biophysics, Academy of Sciences, Brno, Czech Republic.
Biochemistry. 1996 Dec 24;35(51):16705-13. doi: 10.1021/bi961160j.
The novel platinum drugs [{trans-PtCl(NH3)2}2H2N(CH2)nNH2]2+ (1,1/t,t) are currently undergoing preclinical development. The bifunctional DNA binding of these agents allows comparison with that of cisplatin [Farrell et al. (1995) Biochemistry, 34, 15480]. The major DNA lesion of cisplatin, the 1,2-d(GpG) intrastrand adduct, produces a rigid, directed bend 30-35 degrees into the major groove of DNA. We have now completed a structural analysis of the corresponding adduct formed with the dinuclear complexes. Gel retardation assays on 15-22 bp oligonucleotides containing a central d(TGGT) site show that the (Pt,Pt)-intrastrand adducts result in a flexible nondirectional bend. This bend is essentially independent of chain length (n = 2, 4, 6). Chemical reactivity assays indicated a hypersensitivity of the thymine 5' to the adduct and an enhanced sensitivity of the 3'-thymine to OsO4. 2D 1H NMR studies on a d(TG1G2T) adduct of [{trans-PtCl(NH3)2}2H2N(CH2)6NH2]2+ have delineated the structural features responsible for these observations. In contrast to the cisplatin adduct, which displays a 100% N-type sugar of the 5'-G and an anti base conformation of the platinated bases in both solid state and solution, the dinuclear adduct does not display the typical N-type sugar pucker. The base orientations are anti (5'-T), anti (G1), anti/syn (G2), and anti (3'-T) while the sugar conformations are N, S/N, N, and S, respectively. The 5'-T remains stacked with its guanine neighbor while the 3'-T becomes unstacked, a reverse of the situation observed for cis-DDP.
新型铂类药物[{反式-PtCl(NH₃)₂}₂H₂N(CH₂)ₙNH₂]²⁺（1,1/t,t）目前正在进行临床前开发。这些药物的双功能DNA结合特性使其能够与顺铂进行比较[法雷尔等人（1995年），《生物化学》，34卷，15480页]。顺铂的主要DNA损伤，即1,2-二（GpG）链内加合物，会在DNA的大沟中产生一个30 - 35度的刚性、定向弯曲。我们现已完成了与双核配合物形成的相应加合物的结构分析。对含有中心d(TGGT)位点的15 - 22 bp寡核苷酸进行凝胶阻滞分析表明，（Pt,Pt）链内加合物会导致一个灵活的非定向弯曲。这种弯曲基本上与链长无关（n = 2、4、6）。化学反应性分析表明，胸腺嘧啶5'对加合物具有超敏感性，而3'-胸腺嘧啶对OsO₄的敏感性增强。对[{反式-PtCl(NH₃)₂}₂H₂N(CH₂)₆NH₂]²⁺的d(TG₁G₂T)加合物进行的二维¹H NMR研究已经阐明了导致这些观察结果的结构特征。与顺铂加合物不同，顺铂加合物在固态和溶液中均显示5'-G的100% N型糖以及铂化碱基的反式碱基构象，而双核加合物并未显示出典型的N型糖折叠。碱基取向分别为反式（5'-T）、反式（G₁）、反式/顺式（G₂）和反式（3'-T），而糖构象分别为N、S/N、N和S。5'-T与其鸟嘌呤相邻碱基保持堆积，而3'-T则不再堆积，这与顺铂（cis-DDP）的情况相反。
