Detection of hydrogen atom adduct of spin-trap DEPMPO. Relevance for studies of biological systems.

Miloš Mojović (1), Ivan Spasojević (1,2), Goran Bačić (1)

(1) Faculty of Physical Chemistry, (2) Center for Multidisciplinary Studies, University of Belgrade

Hydrogen atom (•H) is known to be generated biologically; however few attempts have been made to develop practical methods for its detection. DEPMPO is a spin-trap successfully used for independent detection of hydroxyl and superoxide radicals. In EPR spectra of DEPMPO/OH and DEPMPO/OOH adducts obtained in biological systems, small “wings” on sides of spectra have been observed, but were usually overlooked or regarded as artifacts. In our study of free radical generated by plant plasma membranes we assumed that these originate from DEPMPO/H adduct. Here we used electrochemical system as a source of •H radicals and tested the ability of DEPMPO to trap them. EPR spectra of spin adducts in such system showed considerable resemblance with additional signal obtained when trapping radicals produced by biological systems. Spectral computer simulations of DEPMPO/H adduct showed that experimentally obtained EPR spectra indeed originate from such adduct. In electrochemical system containing D2O, expected changes in EPR spectra were observed due to well known differences in spin coupling. Therefore, EPR spectroscopy using DEPMPO spin-trap presents suitable technique for detection of hydrogen atoms produced in biological systems. Spectral simulation of •H adducts for other spin-traps was performed and the analysis of their suitability will be presented.

Email: ggbacic@ffh.bg.ac.yu

Address: Faculty of Physical Chemistry, University of Belgrade, Belgrade Studentski trg 12-16