DNA Interstrand Cross-Link Formation by the 1,4-Dioxobutane Abasic Lesion
作者:Lirui Guan、Marc M. Greenberg
DOI:10.1021/ja9061695
日期:2009.10.28
generation of the DOB lesion in DNA reveals that it reversibly forms interstrandcross-links (ICLs) selectively with a dA opposite the 3'-adjacent nucleotide. Product studies and the use of monoaldehyde models suggest that ICL formation involves condensation of the dialdehyde with the exocyclic amine. Mechanistic studies and inspection of molecular models indicate that the local DNA environment and proximity
氧化的无碱基损伤 5'-(2-phosphoryl-1,4-dioxobutane) (DOB) 伴随着各种 DNA 损伤剂的单链断裂产生,这些 DNA 损伤剂从 C5' 位置提取氢原子。DNA 中 DOB 损伤的独立产生表明,它选择性地与 3'-相邻核苷酸对面的 dA 可逆地形成链间交联 (ICL)。产品研究和单醛模型的使用表明 ICL 的形成涉及二醛与环外胺的缩合。分子模型的机理研究和检查表明,局部 DNA 环境和环外胺的接近程度决定了与 dA 反应的选择性。亲电子试剂反应性的邻近控制不同于结构相似的自由扩散分子。由与单链断裂相邻的 DOB 病变形成的 ICL 可能具有重要意义,因为该产物构成“成簇”或“复杂”病变。在核苷酸切除修复时,簇状病变可导致高度有害的双链断裂。
A Novel Polymer Supported Approach to Nucleoside Modification
作者:Suyeal Bae、Mahesh K. Lakshman
DOI:10.1021/jo702558n
日期:2008.5.1
Polymer-supported O-6-(benzotriazol-1-yl)inosine derivatives (Pol-I and Pol-dI) have been synthesized reasonably effectively via reaction of nucleoside phosphonium salts with polymer-linked HOBt (Pol-HOBt). In constast to solution chemistry, use of polymer-supported BOP (Pol-BOP) did not lead to efficient nucleoside loading. Presence of the nucleosides on the support could be readily detected by MAS NMR. Exposure of the polymer-supported nucleosides, Pol-I and Pol-dI, to alcohol, phenol, thiol and amine nucleophiles caused cleavage from the support leading directly to the C-6 modified nucleoside analogues. To our knowledge, these are the first examples of the application of such technology for nucleoside modification. Where possible, results of reactions with the polymer-supported nucleosides are compared to those from solution chemistry, providing insight into the differences between the two techniques. These new polymer-supported nucleosides can be conveniently utilized for diversity-oriented synthesis.
Synthesis of N6,N6-Dialkyladenine Nucleosides Using Hexaalkylphosphorus Triamides Produced in Situ
作者:Mahesh K. Lakshman、Asad Choudhury、Suyeal Bae、Eliezer Rochttis、Padmanava Pradhan、Amit Kumar
DOI:10.1002/ejoc.200800752
日期:——
Reactions between secondary amines and phosphorus trichloride (PCl3) leads to the formation of the corresponding tris(dialkylamino)phosphines or hexaalkylphosphorus triamides [HAPT: (R2N)3P]. Reaction of silyl-protected 2'-deoxyinosine and acetyl-protected inosine with the in situ formed HAPT and iodine (I2) leads to the formation of N6,N6-dialkyl adenosine and 2'-deoxyadenosine. In some cases the