Kazakov S A, Astashkina T G, Mamaev S V, Vlassov V V
Institute of Bioorganic Chemistry, Siberian Division of the USSR Academy of Sciences, Novosibirsk.
Nature. 1988 Sep 8;335(6186):186-8. doi: 10.1038/335186a0.
Metal ions play a crucial role not only in the formation and maintenance of nucleic acid structure, but also in important biochemical conversions of polynucleotides. Some aqueous metal ions, acting as general acid/base (or electrophilic/nucleophilic) catalysts, can induce site-specific cleavage of RNA. DNA is not cleaved efficiently by the non-redox metal-induced mechanism. However, DNA degradation by radicals formed in the metal-catalysed auto-oxidation of ascorbate (or other reducing agents) is well known. In the past, the observed cleavage reactions have not been very specific. Here, we report a non-enzymatic cleavage of single-stranded DNA occurring at unique sites due to redox reactions involving copper. This could be considered a 'self-cleavage' reaction, by analogy with the lead-induced non-redox RNA cleavage reaction. This site-specific cleavage of DNA, stimulated by ascorbate and hydrogen peroxide, is most efficient under physiological conditions, so this phenomenon may have biological significance.
金属离子不仅在核酸结构的形成和维持中起着关键作用，而且在多核苷酸的重要生化转化过程中也发挥着关键作用。一些水合金属离子作为一般酸/碱（或亲电/亲核）催化剂，可以诱导RNA的位点特异性切割。DNA不能通过非氧化还原金属诱导的机制被有效切割。然而，由抗坏血酸（或其他还原剂）在金属催化的自氧化过程中形成的自由基导致的DNA降解是众所周知的。过去，观察到的切割反应并不是非常具有特异性。在这里，我们报告了由于涉及铜的氧化还原反应，单链DNA在独特位点发生的非酶促切割。类似于铅诱导的非氧化还原RNA切割反应，这可以被认为是一种“自我切割”反应。由抗坏血酸和过氧化氢刺激的这种DNA位点特异性切割在生理条件下最为有效，因此这种现象可能具有生物学意义。
