Carbocyclic Nucleoside Isosteres as Potential Antitumor

该项目的主要目标是系统地探测核苷/核苷酸结合酶与构象刚性底物的集合，以了解它们的首选结合模式。这已经通过在双环[3.1.0]己烷模板上构建碳环核苷类似物来实现，所述模板通过将糖的构象锁定在两种优选的天然构象（北或南）之一中而基本上去除了糖部分的固有柔性。该项目的第二个目标是构建修饰的核酸，其掺入许多锁定的核苷酸单元以分别增强或破坏与南构象和北构象相关的典型B-或A-DNA构象。主要研究结果如下： 1)腺苷的锁定对映体（N-MCdA和S-MCdA）的相应的5 '-三磷酸表明，最有效的HIV RT抑制剂（N-MCdA-5'-三磷酸）抑制DNA延伸超过聚合酶位点，并且对通过切除机制起作用的所有HIV抗性菌株显示出极大的有效性。这种方法为克服艾滋病毒耐药性提供了一种新颖而有前途的方法。 2)合成了一系列与EcoR 1自身互补识别序列[ds（5 '-CGCGAATTCGCG-3'）]相对应的短寡脱氧核苷酸（ODNs），其中中间的A和中间的T被锁腺苷和锁胸苷所取代，其结构经NMR、CD和量热法解析。调查结果将于近期公布。 3)一种新的合成开发的北构象，涉及脂肪酶催化的决议步骤的双环[3.1.0]己烷系统是非常成功的，可重复的制备规模的承包商。用于其他DNA合成的所有构件的供应即将到来。

The main objective of this project has been the systematic probing of nucleoside/nucleotide binding enzymes with sets of conformationally rigid substrates to learn about their preferred binding mode. This has been accomplished by constructing carbocyclic nucleoside analogues on a bicyclo[3.1.0]hexane template which essentially removes the inherent flexibility of the sugar moiety by locking the conformation of the sugar in one of the two preferred natural conformations (North or South). A secondary objective of this project has been the construction of modified nucleic acids that incorporate a number of locked nucleotide units to either reinforce or disrupt the typical B- or A-DNA conformations associated with South and North conformations, respectively. The major findings are: 1) The corresponding 5'-triphosphates of the locked antipodes of adenosine (N-MCdA and S-MCdA) showed that that the most effective HIV RT inhibitor (N-MCdA-5'-triphosphate) inhibited DNA elongation beyond the polymerase site and showed great effectiveness against all HIV-resistant strains that function by the excision mechanism. This approach offers a novel and promising way to overcome HIV resistance. 2) A series of short oligodeoxynucleotides (ODNs) corrresponding to the self-complementary EcoR1 recognition sequence [ds(5'-CGCGAATTCGCG-3')] where the middle A's and the middle T's have been replaced by locked adenosines and locked thymidines have been synthesized and the structures solved by NMR, CD and calorimetry. The results will be published shortly. 3) A novel synthesis developed for North conformers involving a lipase-catalyzed resolution step of the bicyclo[3.1.0]hexane system was very successful and reproducible in a preparative scale by a contractor. Supplies of all building blocks for additional DNA syntheses will be forthcoming.