Iron- and Manganese-Containing Superoxide Dismutases: Structure, Distribution, and Evolutionary Relationships

摘要: In 1969, a well-studied family of mammalian copper-containing proteins was discovered to possess superoxide dismutase activity (1). This rather bizarre postulated play protective role for the oxygen-metabolizing organism. Its ubiquity among various tissues led us attempt isolating from an evolutionarily distant species, Escherichia coli (2). Although cell-free extracts E. contained roughly same amount as tissue extracts, enzyme’s behaviour during purification bore no resemblance that bovine enzyme. When enzyme purified homogeniety and concentrated, we did not see familiar blue-green color dismutases. The pink. Undaunted, perhaps comforted by fact some copper are pink (3), set out determine content new dismutase. No could be detected, either colorimetric method or electron paramagnetic resonance (EPR). fact, EPR signal at all detected in native protein. Upon denaturation boiling 0.1 N HCl, however, characteristic six-pronged spectrum manganese(II) appeared.