McConnaughie A W, Jenkins T C
Cancer Research Campaign Biomolecular Structure Unit, Institute of Cancer Research, Sutton, Surrey, UK.
J Med Chem. 1995 Sep 1;38(18):3488-501. doi: 10.1021/jm00018a009.
A series of bifunctional ligands has been developed as prototype DNA-binding combilexins using a DNA template-directed approach. These novel agents contain a 1,3-diaryltriazene linker moiety, present in the established DNA minor groove-binder berenil [1,3-bis(4'-amidinophenyl)-triazene], which is attached to an intercalating acridine chromophore by a functionalized thiazole residue. This 9-arylacridine is predicted to confer rotational freedom to the hybrid molecule and thus facilitate bifunctional interaction with double-stranded DNA through a combination of 'classical' intercalation and minor groove-binding processes. The noncovalent DNA-binding properties of these acridine-triazene combilexins, together with the component molecular fragments, have been examined by fluorescence quenching and thermal denaturation studies with calf thymus DNA and two oligonucleotides, [poly(dA-dT)]2 and [poly(dG-dC)]2. In addition, the binding behaviors of these acridine compounds are compared to those of proflavine (3,6-diaminoacridine) and its 9-phenyl derivative. The results indicate that the hybrid agents (i) are more DNA-affinic than either molecular component, (ii) retain the AT-preferential binding properties of the parent difunctionalized 1,3-diaryltriazene residues, despite weak GC-preferential behavior associated with the acridine chromophore, and (iii) have a reduced binding affinity at pH 7 that reflects the protonation status of the acridine. In contrast, the more basic proflavines show much greater binding affinity and a marked preference for GC-rich DNA sequences. In vitro cytotoxicity data with L1210 mouse leukemia and A2780 human colon cancer cell lines show that the conjugate molecules are approximately 10-40-fold more potent than the acridine or triazene subunits and have activities that compare favorably with those of other reported synthetic combilexins. Intercalative binding modes with a model d(GATACGATAC).d(GTATCGTATC) target duplex have been investigated using molecular modeling techniques. These studies provide a rational basis for the binding properties and suggest that the prototype combilexins can bind in a bimodal manner that induces little distortion of the host DNA duplex. Energy-minimized models for the possible dual interactions are discussed.
一系列双功能配体已通过DNA模板导向方法开发为原型DNA结合复合毒素。这些新型试剂含有一个1,3-二芳基三氮烯连接基团，该基团存在于已确立的DNA小沟结合剂贝尼尔[1,3-双(4'-脒基苯基)-三氮烯]中，它通过一个功能化的噻唑残基连接到一个插入的吖啶发色团上。预计这种9-芳基吖啶会赋予杂合分子旋转自由度，从而通过“经典”插入和小沟结合过程的组合促进与双链DNA的双功能相互作用。通过对小牛胸腺DNA以及两种寡核苷酸[poly(dA-dT)]2和[poly(dG-dC)]2进行荧光猝灭和热变性研究，考察了这些吖啶-三氮烯复合毒素以及组成分子片段的非共价DNA结合特性。此外，将这些吖啶化合物的结合行为与原黄素（3,6-二氨基吖啶）及其9-苯基衍生物的结合行为进行了比较。结果表明，这些杂合试剂：(i) 比任何一种分子组分对DNA的亲和力都更高；(ii) 尽管吖啶发色团具有较弱的GC偏好行为，但仍保留了母体双功能化1,3-二芳基三氮烯残基的AT偏好结合特性；(iii) 在pH 7时结合亲和力降低，这反映了吖啶的质子化状态。相比之下，碱性更强的原黄素显示出更高的结合亲和力，并且对富含GC的DNA序列有明显偏好。用L1210小鼠白血病细胞系和A2780人结肠癌细胞系进行的体外细胞毒性数据表明，共轭分子的效力比吖啶或三氮烯亚基高约10 - 40倍，并且其活性与其他报道的合成复合毒素相当。已使用分子建模技术研究了与模型d(GATACGATAC).d(GTATCGTATC)靶双链的插入结合模式。这些研究为结合特性提供了合理依据，并表明原型复合毒素可以以双峰方式结合，对宿主DNA双链的扭曲很小。讨论了可能的双重相互作用的能量最小化模型。
