Hiramoto K, Johkoh H, Sako K, Kikugawa K
Tokyo College of Pharmacy, Japan.
Free Radic Res Commun. 1993;19(5):323-32. doi: 10.3109/10715769309056521.
When supercoiled plasmid DNA was incubated with 2,2'-azobis (2-amidinopropane)hydrochloride (AAPH) at pH 7.4 in the presence and absence of oxygen, the DNA single strands were effectively cleaved. The breaking in the presence of oxygen was not inhibited by superoxide dismutase and catalase, but inhibited by mannitol, ethanol, butyl hydroxyanisole, thiol compounds, tertiary amines and spin trapping agents N-tert-butyl-alpha-phenylnitrone (PBN) and 5,5-dimethyl-1-pyrroline N-oxide (DMPO). The breaking in the absence of oxygen was inhibited by ethanol, a tertiary amine and PBN. By electron spin resonance spin-trapping with PBN, the carbon-centered radical was detected both in the presence and the absence of oxygen. Hydroxyl radical was detected by use of DMPO only in the presence of oxygen. The DNA breaking activity of AAPH was found to be due primarily to the aliphatic carbon-centered radical. While the reactivity of carbon-centered radicals have received little attention, the aliphatic carbon-centered radical generated from AAPH was found to be highly reactive to break the DNA strands.
当超螺旋质粒DNA在pH 7.4条件下，于有氧和无氧环境中与2,2'-偶氮双(2-脒基丙烷)盐酸盐(AAPH)一起孵育时，DNA单链会被有效切割。在有氧环境下的切割不受超氧化物歧化酶和过氧化氢酶的抑制，但会被甘露醇、乙醇、丁基羟基茴香醚、硫醇化合物、叔胺以及自旋捕获剂N-叔丁基-α-苯基硝酮(PBN)和5,5-二甲基-1-吡咯啉N-氧化物(DMPO)抑制。在无氧环境下的切割则被乙醇、叔胺和PBN抑制。通过用PBN进行电子自旋共振自旋捕获，在有氧和无氧环境中均检测到了以碳为中心的自由基。仅在有氧环境下，使用DMPO检测到了羟基自由基。发现AAPH的DNA切割活性主要归因于脂肪族以碳为中心的自由基。虽然以碳为中心的自由基的反应性很少受到关注，但发现由AAPH产生的脂肪族以碳为中心的自由基对切割DNA链具有很高的反应性。
