Institut für Biochemie, Universität Leipzig, Brüderstr. 34, D-04103, Leipzig, Germany.
Dalton Trans. 2010 Mar 14;39(10):2536-45. doi: 10.1039/b916907e. Epub 2010 Jan 22.
By combining organometallic groups and peptides, a large number of conjugates with interesting new biological properties can be prepared. Especially, attachment to cell-penetrating peptides (CPP) that act as efficient cell delivery vehicles has come to the fore. However, the presence of the metal moiety in such systems can interfere with standard conjugate synthesis procedures which therefore need to be optimized for every new compound. In this work, we report on the preparation of six new cymantrene-sC18 peptide bioconjugates that were prepared by solid phase peptide synthesis (SPPS) techniques. The cymantrene complexes were chosen for their different linker to the peptide, to study the influence of the linker group on cellular uptake and cell viability of the conjugates. Interestingly, the attachment of the metal complex leads to a non-standard cleavage of the Rink amide linker used in the SPPS protocol under trifluoroacetic acid (TFA) treatment, resulting in peptide amides that are N-alkylated at the C-terminus. Furthermore, we found that depending on the type of cymantrene moiety attached, the formation of reactive carbocations which result from decomposition of the resin linker is facilitated and can alkylate the metal complex moiety. Both effects were analyzed by MS/MS studies and cleavage mixtures for efficient elimination of this byproduct formation were identified. Moreover, initial biological testing of the cytotoxicity of one of the bioconjugates gave promising results. Concentration-dependent cell viability studies of Cym1-sC18 on human MCF-7 breast adenocarcinoma cells gave an IC(50) value of 59.8 (+/- 6.7) microM and demonstrate their potential in anticancer chemotherapy.
通过将有机金属基团和肽结合，可以制备出具有有趣新生物学性质的大量缀合物。特别地，将其附着到作为有效的细胞递药载体的穿膜肽（CPP）上已经引起了关注。然而，此类系统中金属部分的存在可能会干扰标准缀合物合成程序，因此需要针对每种新化合物进行优化。在这项工作中，我们报告了通过固相肽合成（SPPS）技术制备的六个新的金刚烷-sC18 肽生物缀合物。选择金刚烷配合物是因为它们与肽的不同连接物，以研究连接体基团对缀合物细胞摄取和细胞活力的影响。有趣的是，金属配合物的附着导致在三氟乙酸（TFA）处理下用于 SPPS 方案的 Rink 酰胺连接体的非标准裂解，导致在 C 末端处 N-烷基化的肽酰胺。此外，我们发现，取决于附着的金刚烷部分的类型，有助于从树脂连接体分解产生的反应性碳正离子的形成，并且可以烷基化金属配合物部分。通过 MS/MS 研究分析了这两种效应，并确定了有效消除该副产物形成的裂解混合物。此外，对一种生物缀合物的细胞毒性的初步生物学测试给出了有希望的结果。金刚烷 1-sC18 对人 MCF-7 乳腺腺癌细胞的浓度依赖性细胞活力研究给出了 59.8（+/-6.7）μM 的 IC50 值，并证明了它们在癌症化疗中的潜力。
