Dedon P C, Borch R F
Biochem Pharmacol. 1987 Jun 15;36(12):1955-64. doi: 10.1016/0006-2952(87)90494-1.
Substitution reactions with biologic nucleophiles appear to govern the antitumor and toxic properties of platinum complexes. In this paper we have characterized the reactions of several platinum antitumor agents with sulfur-containing amino acids, peptides, proteins, and nonbiologic nucleophiles. The rate constants for the reactions of trans-diamminedichloroplatinum(II) (trans-DDP), cis-diamminedichloroplatinum(II) (DDP), diammine (1,1-cyclobutanedicarboxylato)platinum(II) (CBDCA) and cis-diisopropylamine-cis-dichloro-trans-dihydroxy platinum(IV) (CHIP) with cysteine (Cys), methionine (Met), and glutathione (GSH) were determined at 37 degrees. A reactivity ratio of 1:1.5:22:6500 was determined for the reaction of GSH with CHIP, CBDCA, DDP, and trans-DDP respectively. The rate constant for the binding of DDP to DNA, 7.4 X 10(-5) sec-1, decreased to 5.9 X 10(-5) sec-1 and 1.7 X 10(-5) sec-1 in the presence of 0.5 and 5 mM GSH respectively. The products formed in the reaction of GSH with trans-DDP, DDP, and CBDCA were also examined. Under conditions of high platinum concentration (2-3 mM), CBDCA and DDP form large molecular weight species with GSH as indicated by 1H-NMR and ultrafiltration experiments. The complex [Pt(GSH)2 X 3H2O]n was isolated from the reaction of 3 mM DDP with 6 mM GSH. The product formed in the reaction of 3 mM trans-DDP with 6 mM GSH was not macromolecular in nature, and 1H-NMR spectra revealed that platinum was bound to the Cys sulfhydryl group. Rate constants were determined for the reactions of these platinum complexes with diethyldithiocarbamate (DDTC) and thiosulfate, two agents known to reduce platinum-mediated nephrotoxicity. DDTC, but not thiosulfate, was shown to rapidly chelate platinum from [Pt(GSH)2 X 3H2O]n. The effects of DDP, CBDCA, and CHIP on the sulfhydryl-dependent rat renal proximal tubule membrane enzymes alkaline phosphatase (AP), gamma-glutamyltranspeptidase (GGTP), leucine aminopeptidase (LAP), and the Na+/K+- and Mg2+-adenosine-5'-triphosphatases (ATPases) were also investigated in vitro. The ability of platinum complexes to inhibit these enzymes parallels their reactivity with other nucleophiles. DDTC and thiourea were shown to restore activity to platinum-inhibited enzymes. Chloride ion was found to reduce platinum-mediated enzyme inhibition in an unpredictable manner, the greatest effect being observed with LAP and GGTP and the least with the ATPases. None of these renal enzymes was directly inhibited by DDP in vivo.
与生物亲核试剂的取代反应似乎决定了铂配合物的抗肿瘤和毒性特性。在本文中，我们已对几种铂类抗肿瘤药物与含硫氨基酸、肽、蛋白质及非生物亲核试剂的反应进行了表征。测定了反式二氯二氨合铂（II）（trans-DDP）、顺式二氯二氨合铂（II）（DDP）、二氨（1,1-环丁烷二羧酸根）铂（II）（CBDCA）和顺式二异丙胺-顺式二氯-反式二羟基铂（IV）（CHIP）与半胱氨酸（Cys）、蛋氨酸（Met）和谷胱甘肽（GSH）反应的速率常数，反应温度为37℃。分别测定了GSH与CHIP、CBDCA、DDP和trans-DDP反应的反应活性比为1:1.5:22:6500。DDP与DNA结合的速率常数为7.4×10⁻⁵ s⁻¹，在分别存在0.5 mM和5 mM GSH的情况下，该速率常数分别降至5.9×10⁻⁵ s⁻¹和1.7×10⁻⁵ s⁻¹。还对GSH与trans-DDP、DDP和CBDCA反应生成的产物进行了检测。在高铂浓度（2 - 3 mM）条件下，¹H-NMR和超滤实验表明，CBDCA和DDP与GSH形成了大分子物质。从3 mM DDP与6 mM GSH的反应中分离出了配合物[Pt(GSH)₂·3H₂O]ₙ。3 mM trans-DDP与6 mM GSH反应生成的产物本质上不是大分子，¹H-NMR光谱显示铂与Cys巯基结合。测定了这些铂配合物与二乙基二硫代氨基甲酸盐（DDTC）和硫代硫酸盐反应的速率常数，已知这两种试剂可降低铂介导的肾毒性。结果表明，DDTC而非硫代硫酸盐能迅速从[Pt(GSH)₂·3H₂O]ₙ中螯合铂。还在体外研究了DDP、CBDCA和CHIP对巯基依赖性大鼠肾近端小管膜酶碱性磷酸酶（AP）、γ-谷氨酰转肽酶（GGTP）、亮氨酸氨肽酶（LAP）以及Na⁺/K⁺-和Mg²⁺-腺苷-5'-三磷酸酶（ATP酶）的影响。铂配合物抑制这些酶的能力与其与其他亲核试剂的反应活性平行。结果表明，DDTC和硫脲可使铂抑制的酶恢复活性。发现氯离子以不可预测的方式降低铂介导的酶抑制作用，对LAP和GGTP的影响最大，对ATP酶的影响最小。在体内，这些肾酶均未被DDP直接抑制。
