鸟嘌呤核苷酸与核黄素氧化性自由基之间的电子转移研究

ONE-ELECTRON OXIDATION OF dGMP BY OXIDIZED RIBOFLAVIN RADICAL IN AQUEOUS SOLUTION: A LASER FLASH PHOTOLYSIS STUDY

应用 ２４８ ｎｍ激光光解时间分辨吸收方法，研究了 ２’－鸟嘌呤核苷酸与核黄素氧化性自由基之间的单电子转移机理，给出了电子转移的直接证据。改变溶液的酸碱性，探讨了不同形式自由基之间电子转移的可行性。

Using time-resolved technique of 248nm laser flash photolysis, electron transfer from 2'-deoxyguanosine-5'-monophospha (dGMP) to oxidized riboflavin (VB2) radical was observed for the first time due to the buildup of the oxidized dGMP radical matching the decay of oxidized riboflavin radical at different pH values in aqueous solution. The reaction rate constants were derived to be 5.6x 108, 5.8x 108 and 6.2x 108dm3·mol-1.s-1 at pH 3, 5 and 7.5, respectively. The direct observation of oxidized guanine radical has provided unambiguously direct initial proof for photosensitization process of dGMP by oxidized riboflavin radical.