The ABC’s of the Reactions between Nitric Oxide, Superoxide, Peroxynitrite and Superoxide Dismutase

The interplay between nitric oxide and superoxide to form peroxynitrite is a major biological process that competes in a remarkably subtle fashion with superoxide dismutase in vivo. The complex interactions between superoxide, nitric oxide reveals some extraordinary features about the difficulties of effectively scavenging of superoxide in a biological system. The discovery of dominant mutations in the cytosolic Cu,Zn SOD leading to the selective death of motor neurons in ALS highlights how subtle the scavenging of superoxide can be in the presence of low concentrations of nitric oxide.