SOD (EC 1.15.1.1) was first isolated from bovine blood as
a green copper protein (Mann and Keilin, 1938) whose biological
function was believed to be copper storage. Over the
years, the enzyme has been variably referred to as erythrocuprein,
indophenol oxidase, and tetrazolium oxidase. The
catalytic function of the enzyme was discovered by McCord
and Fridovich (1969). The enzyme is ubiquitous, being widely
distributed among 02-consuming organisms, aerotolerant anaerobes,
and some obligate anaerobes