School of Chemistry and Biochemistry, ‡Parker H. Petit Institute of Bioengineering and Bioscience, and §Laser Dynamics Laboratory, Georgia Institute of Technology , Atlanta, Georgia 30332, United States.
J Phys Chem B. 2017 Sep 28;121(38):8975-8983. doi: 10.1021/acs.jpcb.7b08156. Epub 2017 Sep 19.
Ultraviolet resonance Raman (UVRR) spectroscopy is a label-free method to define biomacromolecular interactions with anticancer compounds. Using UVRR, we describe the binding interactions of two Pt(II) compounds, cisplatin (cis-diamminedichloroplatinum(II)) and its isomer, transplatin, with nucleotides and genomic DNA. Cisplatin binds to DNA and other cellular components and triggers apoptosis, whereas transplatin is clinically ineffective. Here, a 244 nm UVRR study shows that purine UVRR bands are altered in frequency and intensity when mononucleotides are treated with cisplatin. This result is consistent with previous suggestions that purine N7 provides the cisplatin-binding site. The addition of cisplatin to DNA also causes changes in the UVRR spectrum, consistent with binding of platinum to purine N7 and disruption of hydrogen-bonding interactions between base pairs. Equally important is that transplatin treatment of DNA generates similar UVRR spectral changes, when compared to cisplatin-treated samples. Kinetic analysis, performed by monitoring decreases of the 1492 cm band, reveals biphasic kinetics and is consistent with a two-step binding mechanism for both platinum compounds. For cisplatin-DNA, the rate constants (6.8 × 10 and 6.5 × 10 s) are assigned to the formation of monofunctional adducts and to bifunctional, intrastrand cross-linking, respectively. In transplatin-DNA, there is a 3.4-fold decrease in the rate constant of the slow phase, compared with the cisplatin samples. This change is attributed to generation of interstrand, rather than intrastrand, adducts. This longer reaction time may result in increased competition in the cellular environment and account, at least in part, for the lower pharmacological efficacy of transplatin.
紫外共振拉曼（UVRR）光谱是一种无标记方法，可用于定义与抗癌化合物的生物大分子相互作用。使用 UVRR，我们描述了两种铂（II）化合物顺铂（顺式二氨二氯铂（II））及其异构体反铂与核苷酸和基因组 DNA 的结合相互作用。顺铂与 DNA 和其他细胞成分结合并引发细胞凋亡，而反铂在临床上无效。在这里，244nm UVRR 研究表明，当单核苷酸与顺铂处理时，嘌呤 UVRR 带的频率和强度发生改变。这一结果与嘌呤 N7 提供顺铂结合位点的先前建议一致。铂加合物加到 DNA 中也会导致 UVRR 光谱发生变化，这与铂结合嘌呤 N7 和破坏碱基对之间氢键相互作用一致。同样重要的是，与顺铂处理的样品相比，反铂处理的 DNA 会产生类似的 UVRR 光谱变化。通过监测 1492cm 带的减少来进行的动力学分析揭示了两相动力学，并且与两种铂化合物的两步结合机制一致。对于顺铂-DNA，速率常数（6.8×10 和 6.5×10 s）分别分配给单功能加合物和双功能、链内交联的形成。在反铂-DNA 中，与顺铂样品相比，慢相的速率常数降低了 3.4 倍。这种变化归因于生成链间而非链内加合物。这种更长的反应时间可能会导致细胞环境中竞争增加，并至少部分解释反铂较低的药理功效。
