Department of Chemistry and Industrial Chemistry (DCCI), University of Pisa, Via Moruzzi, 13, 56124 Pisa, Italy; Laboratory of Metals in Medicine (MetMed), Department of Chemistry "U. Schiff", University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy.
IAdChem (Institute for Advanced Research in Chemical Science) and Department of Inorganic Chemistry, Universidad Autónoma de Madrid, 28049, Spain.
J Inorg Biochem. 2018 Apr;181:11-17. doi: 10.1016/j.jinorgbio.2018.01.002. Epub 2018 Jan 10.
The tetranuclear Pt complex (PtL) (where L is the anion derived from para-isopropyl thiosemicarbazone) was first described in A.G. Quiroga et al., J. Med. Chem. 41, 1998, 1399-1408. (PtL) manifests antiproliferative properties toward various cancer cell lines being a promising anticancer drug candidate. Yet, details of its reactivity with biomolecules have not been elucidated. To this end, we investigated the reactions of (PtL) with a few model proteins, i.e. bovine pancreatic ribonuclease (RNase A), cytochrome c (Cyt c) and hen egg white lysozyme (Lysozyme), through electrospray ionization mass spectrometry and other biophysical methods. A rich reactivity of (PtL) with the above-mentioned model proteins is observed, leading to the formation of numerous metallodrug-protein adducts. The tetranuclear complex breaks down and various fragments bind proteins up to high metal/protein ratios; this typically results into very complicated mass spectral patterns. However, some of the main mass peaks could be assigned in the case of the Lysozyme adduct. In addition, crystallographic data were obtained for the (PtL)/Lysozyme and (PtL)/RNase A adducts pointing at His side chains as the primary binding sites for monometallic Pt fragments. Notably, a few selected features of the interactions observed in the (PtL)/protein adducts were reproduced by reacting (PtL) with a small molecule, i.e. N-methylimidazole. In conclusion, the present study confirms the prodrug nature of the tetraplatinum complex, clarifies one possible pathway for its activation through cluster disassembly and allows initial identification of adducts formed with a representative protein.
第一个描述四核铂配合物（PtL）（其中 L 是来自对异丙基硫代半卡巴腙的阴离子）的是 A.G. Quiroga 等人，J. Med. Chem. 41, 1998, 1399-1408。（PtL）对各种癌细胞系表现出抗增殖特性，是一种很有前途的抗癌药物候选物。然而，其与生物分子反应的细节尚未阐明。为此，我们通过电喷雾电离质谱和其他生物物理方法研究了（PtL）与几种模型蛋白，即牛胰腺核糖核酸酶（RNase A）、细胞色素 c（Cyt c）和鸡卵清溶菌酶（Lysozyme）的反应。观察到（PtL）与上述模型蛋白的丰富反应性，导致形成许多金属药物-蛋白加合物。四核配合物分解，各种片段与蛋白质结合，直至达到高金属/蛋白质比；这通常会导致非常复杂的质谱模式。然而，在 Lysozyme 加合物的情况下，可以对一些主要的质量峰进行分配。此外，还获得了（PtL）/Lysozyme 和（PtL）/RNase A 加合物的晶体学数据，表明 His 侧链是单金属 Pt 片段的主要结合位点。值得注意的是，通过将（PtL）与小分子，即 N-甲基咪唑反应，再现了在（PtL）/蛋白加合物中观察到的一些相互作用的特征。总之，本研究证实了四核铂配合物的前药性质，阐明了其通过簇解组装激活的一种可能途径，并允许对与代表性蛋白质形成的加合物进行初步鉴定。
