Superoxide dismutases in photosynthetic organisms: Absence of the cuprozinc enzyme in eukaryotic algae

Abstract

Superoxide dismutases in photosynthetic organisms at different evolutionary levels were characterized using the criterion that the Cu,Zn-enzyme is sensitive to cyanide while the Mn- and Fe-enzymes are insensitive. The effect of the antibody against spinach Cu,Zn-superoxide dismutase was also tested as a means of distinguishing the several forms of the enzyme. Superoxide dismutase activity in extracts from photosynthetic bacteria, prokaryotic algae (blue-green algae), and eukaryotic algae (red, green, and brown algae, diatoms, Euglena, and Charophyta) were insensitive to cyanide and to the antibody, suggesting the presence of the Fe- and/or Mn-enzymes and the absence of the Cu,Zn-enzyme. In contrast, ferns, mosses, and seed plants including gymnosperms and angiosperms contained the Cu,Zn-superoxide dismutase in addition to the cyanidein-sensitive enzyme in soluble or bound form. Although an aerial green alga lacks the Cu,Zn-superoxide dismutase, aquatic angiosperms and ferns, like other land plants, contain this form of superoxide dismutase. Thus the distribution of the Cu,Zn-superoxide dismutase does not reflect the habitat but, rather, the phylogeny of the organism. The relation between the oxygen concentration in the atmosphere and the appearance of various forms of superoxide dismutase during the evolution of photosynthetic organisms is discussed.