肌动蛋白与顺铂、反铂的相互作用

利用1H-NMR研究了肌动蛋白(actin)与顺铂、反铂的相互作用,测定了肌动蛋白的聚合临界浓度,并研究了顺伯、反铂对它的影响。实验结果显示顺伯和反驳都能导致微丝（F-actin）解聚。在相同浓度下,反铂的作用更加明显。对于肌动蛋白单体(G-actin),顺铂在低浓度下促进其聚合。反铂则只表现出抑制G-actin的聚合。讨论了顺铂、反铂与G-actin可能的结合位点,顺铂可能与Cys-10和Cys-285结合,而反铂不与Cys-10结合。     

符合经典构效关系的抗肿瘤铂类药物

综述了自顺铂、卡铂后符合经典构效关系的铂类抗肿瘤药物的发展概况，按载体配基和离去基团的结构特征进行了分类，总结了各类配合物的构效关系和临床进展，其中重点对手性二胺配体的铂(Ⅱ)配合物进行了介绍。并讨论了顺铂、卡铂、奥沙利铂的作用机理。     

顺铂,碳铂与鸟苷,L—蛋氨酸反应动力学比较研究

自发现顺铂具有抗癌活性以来,人们一直致力于它的抗癌机理研究。很多结果表明顺铂与蛋白质核苷酸(DNA)作用时主要与DNA中鸟嘌呤的N_7配位,通过形成链内交联作用造成DNA损伤。顺铂在显示抗癌活性的同时,也表现出较强的毒副作用,有文献认为毒性可能与形成Pt—S键抑制生物体内的巯基酶有关。     

顺铂耐药的分子机制

顺铂被广泛用于多种类型的实体肿瘤的临床治疗.DNA是顺铂的主要靶点,顺铂结合会导致DNA损伤并诱发细胞凋亡.然而,顺铂化疗常常受到内在的和获得性的耐药性的限制.在过去30多年里,大量的研究致力于对顺铂耐药性的理解,并且提出了几种导致顺铂耐药性的分子机制.这些机制显示顺铂的耐药性具有多因素特征.本文系统描述和讨论了顺铂的耐药性机制,包括细胞内药物积累的减少,药物去活作用的增强,DNA修复作用,DNA损伤反应和凋亡通路的变化以及一些间接信号通路的调控影响.     

抗癌药顺铂对照品制备及其纯度测定

提出了抗癌药顺铂对照品的新制备方法并进行其纯度测定。该方法涉及在二甲基甲酰胺中用18-冠醚-6选择沉淀trans-[Pt(NH3)2Cl2],然后用NaCl溶液反析顺铂、分离K[Pt(NH3)Cl3]。采用HPLC和TLC法测定制备出的顺铂。结果表明所制备的顺铂纯度大于99.5%,有关杂质均小于0.1%,满足作为对照品的要求。     

高效液相色谱法测定顺铂注射液中顺铂的含量

顺铂含量的测定方法有灼烧重量法[1]、高效液相色谱法[2,3]、络合滴定法[4]。顺铂注射液作为新剂型,其主含量顺铂的分析方法一直为省级标准,采用SnCl2显色法[5],该法所测值是二价铂化合物的总含量,对顺铂无选择性。文献上也有采用高效液相色谱法[6]的报道,但该法存在着:1.杂质峰与主峰分离度不够(Rs<1.5);2.方法重现性较差;3.对柱效要求高的缺点,其主要原因是所选色谱系统不理想。为此,本研究以高效液相色谱法测定顺铂注射液中顺铂的含量,取得了满意的结果。1　实验部分1.1　仪器和试剂SHIMADZULC 10A系统,双LC 10AD高压泵,DGU…     

铂与社会

铂是一种重要的贵金属,是化工、能源、石油炼制上的常用催化剂,是冶金工业制备高温电阻温度计的必须材料,是制造白金首饰的基本原料.铂的化合物——顺铂更是目前结构最简单的抗癌药物.本文概述了铂的性质、应用和工业制法,介绍了白金首饰的类型和检验方法,顺铂的抗癌机理.     

抗癌药物的先驱——顺铂

顺铂在人类抗癌历程中发挥着里程碑式的作用,本文重点介绍顺铂的作用机理、致毒机理和细胞对其产生耐药性的机理,并由此指出铂类药物所存在的缺陷以及发展方向。     

顺-二氯二氨合铂(Ⅱ)与红细胞膜蛋白的相互作用

顺铂可与红细胞膜蛋白结合,并使膜收缩蛋白交联聚合,巯基是顺铂的可能结合部位,顺铂造成膜蛋白构象或在膜内组装的改变,这些结果支持了我们提出的顺铂作用的多靶分子模型。     

铂(Ⅱ)配合物与金属硫蛋白结合反应的动力学

通过对顺铂及相关配合物与兔肝金属硫蛋白(MT)反应平衡产物的组成分析表明.铂(Ⅱ)化硫蛋白中角分子MT可以结合7.0当量Pt(Ⅱ),而且结构不同的顺. 反铂和四氯铂酸钾对应有相同的化学计量关系,研究了这些配合物与兔肝Zn~7,MT~2反应的动力学,发现Pt(Ⅱ)与MT的反应为三个速度不同的控制步骤,求得了相应的表观一级反应速率常数K~Ⅰ.K~Ⅱ和K~Ⅲ首次观测到在相同条件下,反铂与MT 的反应速度比顺铂大3-5倍,初始反应速度常数K~Ⅰ与Pt(Ⅱ)的存在形式及有效浓度有很强的依赖关系,而同一种配合物在不同pH和浓度下.K~Ⅱ和K~Ⅲ无明显变化.提出了铂(Ⅱ) 配合物与MT反应的动力学机理,并根据顺.反铂与MT反应动力学性质的不同, 对它们抗癌活性及毒性差异的原因进行了讨论.     

Internalization of Ineffective Platinum Complex in Nanocapsules Renders It Cytotoxic

Anticancer therapy by platinum complexes, based on nanocarrier‐based delivery, may offer a new approach to improve the efficacy and tolerability of the platinum family of anticancer drugs. The original rules for the design of new anticancer platinum drugs were affected by the fact that, although cisplatin (cis‐[PtCl₂(NH₃)₂) was an anticancer drug, its isomer transplatin was not cytotoxic. For the first time, it is demonstrated that simple encapsulation of an inactive platinum compound in phospholipid bilayers transforms it into an efficient cytotoxic agent. Notably, the encapsulation of transplatin makes it possible to overcome the resistance mechanisms operating in cancer cells treated with cisplatin and prevents inactivation of transplatin in the extracellular environment. It is also shown that transplatin delivered to the cells in nanocapsules, in contrast to free (nonencapsulated) complex, forms cytotoxic cross‐links on DNA.     

DSC Studies of the Effects of Cisplatin and Transplatin on G-Actin

The effects of cisplatin and its trans isomer transplatin on the thermal denaturation of G-actin were studied with a Micro DSC-III differential scanning calorimeter. The denaturation enthalpy of G-actin was found to be 12 J g^–1, and the denaturation temperature was 328 K. The thermal denaturation curve showed that increasing cisplatin concentration decreased the enthalpy change. However, after the ratio of cisplatin to G-actin attained 8:1 (mol:mol), the denaturation enthalpy no longer decreased. Transplatin decreased the enthalpy change more rapidly. In contrast with cisplatin, the denaturation peak at 328 K disappeared, and a strong exothermic peak appeared at 341 K when the ratio of transplatin to G-actin was 8:1 (mol:mol). The enthalpy change was 75 J g^–1, which is far in excess of the range of weak interactions. This strong exothermic phenomenon probably reflects the agglutination of protein. The effects of cisplatin and transplatin on the number of the free thiol groups of G-actin are discussed.This revised version was published online in November 2005 with corrections to the Cover Date.     

Characterization of platinum anticancer drug protein-binding sites using a top-down mass spectrometric approach

A proof-of-principle study on the application of a top-down electrospray ionization Fourier transform ion cyclotron resonance mass spectrometric approach for characterization of the primary binding sites of the platinum anticancer agents cisplatin, transplatin, and oxaliplatin on ubiquitin is presented. Through employment of different fragmentation techniques, the binding sites of cisplatin and oxaliplatin were found at N-terminal methionine-containing ubiquitin fragments, while transplatin was observed to be attached to 19Pro-Ser-Asp-Thr-Ile-Glu24. The binding to proteins is of particular relevance for the mode of action of metallodrugs with regard to (de)activation, transport, excretion, etc. To the best of our knowledge, this is the first top-down mass spectrometric study on the protein binding site characterization of transition-metal anticancer agents and demonstrates the potential of the applied technique for investigating metal drug-protein interactions.     

Hydration process as an activation of trans- and cisplatin complexes in anticancer treatment. DFT and ab initio computational study of thermodynamic and kinetic parameters

The thermodynamic and kinetic aspects of hydration reactions of cis-/transplatin were explored. The polarizable continuum model was used for estimation of solvent effects. Using the B3LYP/6-31+G(d) method, the structures were optimized and vibrational frequencies estimated. Interaction energies and activation barriers were determined at the CCSD(T)/6-31++G(d,p) level within the COSMO approach. An associative mechanism was assumed with a trigonal-bipyramidal structure of the transition state. Within the applied model, all the hydration reactions are slightly endothermic. The Gibbs energies of cisplatin hydration amount to 7.0 and 14.2 kcal/mol for the chloride and ammonium replacement, respectively. Analogous values for the transplatin reactions are 6.8 and 11.9 kcal/mol. The determined rate constants are by several (three to four) orders of magnitude larger for the dechlorination process than for deammination. The cisplatin dechlorination rate constant was established as 1.3 x 10(-4) s(-1) in excellent accord with the experiment.     

Separation of some platinum(II) complexes by ionic strength gradient on a solvent-generated ion-exchange sorbent.

The compatibility of ionic strength gradient with solvent-generated ion-exchange chromatography on an octadecylsilica sorbent was proven for a mobile phase containing octanesulphonate. Only a slight baseline shift was observed during the gradient of the phosphate buffer, even at 210 nm. An equilibration time of 3 min between the runs was sufficient to obtain retention times with a reproducibility better than 1%. The compounds separated were cisplatin, carboplatin and related neutral and cationic platinum(II) complexes, including transplatin and the aquation products of cisplatin.     

ESI mass spectrometry and X-ray diffraction studies of adducts between anticancer platinum drugs and hen egg white lysozyme

The interactions of cisplatin and its analogues, transplatin, carboplatin and oxaliplatin, with hen egg white lysozyme were analysed through ESI mass spectrometry, and the resulting metallodrug-protein adducts identified; the X-ray crystal structure of the cisplatin lysozyme derivative, solved at 1.9 A resolution, reveals selective platination of imidazole Nepsilon of His15.     

辐照三嵌段聚苯乙烯-丁二烯-4-乙烯基吡啶共聚物离子交换膜性能的研究——Ⅰ.季铵化、磺化试剂、反应温度对膜性能的影响

本文分别研究了以氯磺酸、浓硫酸为磺化试剂及一碘甲烷、二碘甲烷为季铵化试剂所制备的辐照聚笨乙烯-丁二烯-4-乙烯基吡啶离子交换膜的膜交换当量、吸水率,膜电位及膜电导率的性能。研究表明以氯磺酸为磺化试剂所制备的离子交换膜其离子交换当量比以浓硫酸寿磺化试剂的要高。以一碘甲烷为季铵化试剂制备的离子交换膜其离子交换当量要比以二碘甲烷为季铵化试剂的要高,但机械强度差。在相同条件下,提高反应温度,有利于膜的季铵化反应,而不利于膜的磺化反应。所制备的阴、阳离子交挟膜膜交换当量、膜电导率、吸水率及膜电位四者的关系是膜交换当量高则膜电导率、含水率高,而膜电位则下降。     

Cisplatin-induced alteration on membrane composition of A549 cells revealed by ToF-SIMS

Cisplatin has been clinically used for treatment of solid tumors such as non–small-cell lung cancer for decades. However, tumor resistance may be acquired with losing the antitumor activity of cisplatin. As cellular membrane is the first barrier that cisplatin has to overcome before its further action inside the cells, the membrane composition must play a vital role in the cisplatin uptake and excretion, which further influences cisplatin sensitivity. In this work, we applied time-of-flight secondary ion mass spectrometry (ToF-SIMS) surface analysis combined with principle component analysis to distinguish the differences of cell membrane composition between non–small-cell lung cancer cells (A549) and its cisplatin resistant counterpart A549/DDP cells. The decreased phosphatidylcholine content and more abundant cholesterol were observed in the drug resistant cell surfaces, indicating the decreased membrane fluidity of A549/DDP cells. Moreover, we further compared membrane composition of A549 and A549/DDP cells after being treated with different concentrations of cisplatin. A higher composition level of proteins was discovered on all groups of A549/DDP cell membranes. The altered surface chemistry of cellular membranes induced by cisplatin indicates the significance of membrane structures in the drug resistance, which deserves further investigations to this regard.     

Insights into the reaction of transplatin with DNA and proteins: methionine-mediated formation of histidine-guanine trans-Pt(NH3)2 cross-links

Simultaneous exposure of transplatin to polypeptides and DNA was mimicked by using a model peptide-oligonucleotide conjugate. Initially formed methionine-guanine chelates evolved into adducts with histidine-guanine trans-Pt(NH3)2 cross-links that differed in constitution and stability from those formed by reaction of the same conjugate with the anticancer drug cisplatin. This finding may be due to different capacities of the two diamminedichloroplatinum(II) complexes to interfere with biological processes and may explain their differing cytotoxicities.