A novel hydrogen-donating drug suppresses haem damage from myoglobin mediated by oxidised low density lipoproteins.

The peroxidaee action of myoglobin and haemoglobin has been recognised for several decades [l]. The interaction of MetMb with peroxides involves the formation of a ferry1 (iron IV-0x0) species and a protein radical [2]. It is not clear which of these species is responsible €or oxidative damage to biological substrates. It has been proposed that the radical on the surface of the haem protein is located on tyrosine-103, in equine MetMb [3,4]. This protein radical has been characterised by applying epr, both stop-flow and spin-trapping (DMPO). The DMPO-adduct decays rapidly being reduced to approximately 10% of its initial intensity after 10 minutes. Our recent studies [5] have provided evidence that it is a peroxyl radical, on the surface of the haem protein, and not its precursor phenoxyl radical which initiates oxidative damage to erythrocyte membranes.