Is molecular oxygen, O(2), the reactive radical behind oxidations of (aut)oxidable agents to which the bases of DNA belong?

摘要

The transfer of charges to reducible oxygen plays a basic role in the supply of energy to living organisms. These electron transfer (ET) reactions may be performed by selenium (Se) enzymes and autoxidable agents. Among the molecules which have satisfactory structures for this purpose are (hypo)xanthine, dopamine (DA), serotonin, arginine, creatine, thyroid hormones T(2)/T(3)/T(4) and the bases of DNA. Single-strand DNA breaks may be initiated by these reactions to yield the bases for the transfer of charges. But a high rate of DNA single-strand breaks may be caused by destructive oxidations. If the activity of the O(2) protective enzymes (Se enzymes such as gluthatione peroxidase (Gpx), superoxide dismutase (SOD) and catalase) is limited, the oxygen species H(2)O(2), O(2)(-) and OH generate free O(2). I believe that randomized oxidations are performed by the radical O(2) (two unshared orbitals) when it is not enzyme protected. Among the substances exposed to oxidation are the autoxidable agents. Are the bases of DNA and RNA to be included in these, taking part in ET reactions? Copyright 2002, Elsevier Science Ltd. All rights reserved.