ABSTRACT
This chapter focuses on the system of enzymes that react directly with the intermediate reduction products to remove them, in fact on a single enzyme–the antioxidant enzyme copper-zinc superoxide dismutase (CuZnSOD). It presents an overview of the biophysical properties of CuZnSOD followed by a review of some of the more recent biological results, particularly those relating to biological function, including a discussion of the role of this enzyme in the human neurodegenerative disease amyotrophic lateral sclerosis. The chapter broadens the scope to include other superoxide dismutases (SODs), particularly the manganese superoxide dismutases (MnSOD), since the SODs are closely linked by a common function. CuZnSOD has the ability to react with peroxynitrite to catalyze the nitration of tyrosine residues. Peroxynitrite is formed by the rapid reaction of superoxide with nitric oxide in vivo and it is possible that the toxicity of mutant CuZnSODs is mediated through the further reaction of this powerful oxidant with the enzyme to nitrate protein-bound tyrosine residues.
