生命金属寡核苷酸螯合物的制备及反应机理
来源期刊：中南大学学报(自然科学版)1997年第2期
论文作者：李晓如 马祥志 饶桂春 文志斌
文章页码：92 - 95
关键词：寡聚核苷酸； 生命金属离子； 螯合物； 剪切
Key words：oligonucleotide； biometal ions； chelate； cleavage
摘 要：制备了5′端共价连接EDTA的寡聚核苷酸与生命金属的螯合物ODN－5′－EDTAM(n＋)，其中M(n＋)为FE(Ⅱ)，Co(Ⅱ)或Cu(Ⅱ)；分析、计算了这3个螯合物形成的最佳 PH值范围，ODN－EDTA·FE(Ⅱ)为PH5.8～8.6，ODN－EDTA·Co(Ⅱ)为PH4.6～8.1，ODN－EDTA·Cu(Ⅱ)为 PH3.4～5.7；在此条件下，剪切反应必须的Mg2+并不与FE(Ⅱ)，Co(Ⅱ)或Cu(Ⅱ)竞争EDTA，也不会形成沉淀；讨论了 ODN－EDTA·M(n＋)切割DNA双链的反应机理：修饰寡核苷酸通过氢键在DNA双链的大沟结合形成三链体，在O2和还原剂DTT作用下，FE作为催化剂，产生羟基自由基，氧化糖环，切割EDTA·FE(Ⅱ)附近的DNA双链.
Abstract: The chelates of biometal ions with EDTA covalently linked to the 5′-end of oligodeoxynucleotides(ODN), i. e. , ODN-5′-EDTA·M(Ⅱ), are prepared, in which M(Ⅱ)is Fe(Ⅱ), Co(Ⅱ)or Cu(Ⅱ). The optimization of pH value for forming these chelates is calculated. For ODN-5′-EDTA·Fe(Ⅱ) pH value is 5 8 to 8 6, pH 4 6～8 1 for ODN-5′-EDTA·Co(Ⅱ), pH 3. 4～5. 7 for ODN-5′-EDTA·Cu(Ⅱ). Under such pH value conditions neither can Mg 2+ ions, necessary for cleavage reaction, be competitive with Fe(Ⅱ), Co(Ⅱ) or Cu(Ⅱ) to form EDTA Chelate, nor can it be precipitated. The cleavage mechanism of ODN-5′-EDTA·Fe(Ⅱ) for DNA duplex is discussed. Modified ODN binds with DNA duplex in the major groove via hydrogen bond to form triple helix . In the presence of oxygen and reducing agent DTT(dithiothreitol) hydroxyl radicals species are generated as intermediates by the catalysis of metal iron, and then oxidize the ribo ring and cut the double stranded DNA at the sites close to EDTA·M(Ⅱ).
