Vanadyl‐induced Fenton‐like reaction in RNA

FEBS Letters

Carmichael, Alasdair J.¹ 

[1] Radiation Biochemistry Department, Armed Forces Radiobiology Research Institute, Bethesda, MD 20814-5145, USA

关键词: Vanadium;    Vanadyl;    Hydrogen peroxide;    Hydroxyl radical;    Electron spin resonance;    Spin trapping;   

DOI  :  10.1016/0014-5793(90)80662-3

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Vanadyl (VO²⁺) complexee to RNA reacts with hydrogen peroxide in a Fenton-like manner producing hydroxyl radicals ('OH). The hydroxyl radicals can be spin trapped with 5,5-dimethyl-1-pyrroline-1-oxide (DMPO) forming the DMPO-OH spin adduct. In addition, in the presence of ethanol the formation of the hydroxyethyl radical adduct of DMPO (DMPO-ETOH) confirms the production of hydroxyl radicals by the RNA/ VO²⁺ complex. When the reaction between the RNA/VO²⁺ complex and H₂O₂ is carried out in the presence of the spin trap 2-methyl-2-nitrosopropane (MNP), radicals produced in the reaction of ^.OH with RNA are trapped. Base hydrolysis of the MNP-RNA adducts (pH 12) followed by a reduction in the pH to pH 7 after hydrolysis is complete, yields an MNP adduct with a well-resolved ESR spectrum identical to the ESR spectrum obtained from analogous experiments with poly U. The ESR spectrum consists of a triplet of sextets (a _N = 1.48 mT, a _N ^β = 0.25 mT and a _H ^β = 0.14 mT), indicating that the unpaired nitroxide electron interacts with the nuclei of a β-nitrogen and β-hydrogen. The results suggest that the ^.OH generated in the RNA/VO²⁺ reaction with H₂O₂ add to the C(5) carbon of uracil forming a C(6) carbon centered radical. This radical is subsequently spin trapped by MNP.

【 授权许可】

Unknown