Fig. 6.

Fluorescent and magnetic resonance detection methodology. MPO peroxidase activity catalyzes the one-electron oxidation of the substrate, which converts it to a free radical metabolite. Although the free radical metabolite was proposed to bind to protein [126], there is more evidence to suggest that a quinoneimine or o-quinone serotonin metabolite is the proximate electrophile that will bind to protein [127,128]. (Modified from [126]).