Protection against peroxynitrite

Peroxynitrite formed in vivo from superoxide and nitric oxide can mediate o xidation, nitration, or nitrosation reactions, leading to impaired function , toxicity, and alterations in signaling pathways. Protection against perox ynitrite is important for defense of normal tissue? especially during infla mmation. Biological protection against peroxynitrite is organized in three categories: prevention, Interception, and repair. Prevention is the control of the formation of peroxynitrite precursors, nitric oxide and superoxide. Interception is by direct reaction with peroxynitrite, leading to non-toxi c products. In this regard, organoselenium compounds, metalloporphyrin deri vatives, and peroxidases (e.g. glutathione peroxidase and myeloperoxidase) exhibit high second-order rate constants with peroxynitrite. Ebselen, like glutathione peroxidase, protects in a catalytic fashion utilizing glutathio ne as reductant in the peroxynitrite reductase reaction. Protection by meta lloporphyrins can be maintained through glutathione or ascorbate, Repair pr ocesses remove damaged products and restitute intact biomolecules, (C) 1999 Federation of European Biochemical Societies.