STUDIES ON NITRATE REDUCTASE OF CLOSTRIDIUM PERFRINGENS. III. COMPARISON OF NITRATE REDUCTASE FROM FIVE STRAINS OF C. PERFRINGENS

Abstract

Since nitrate reductase from a strain of Clostridium perfringens, HM-1, is unique soluble reductase using ferredoxin as electron donor, properties of five strains of this species, HM-1, Am-1, KOA-3, DA-7, and PB6KN5-L9, were investigated using cell extracts for comparison. Though there were two groups of nitrate reductases with different electrophoresis mobilities and isoelectric points, namely 5.5 and 5.7, the molecular weights of HM-1, Am-1, KOA-3, and PB6KN5-L9 were all estimated to be 9×10⁴ by measuring the Rm's at different gel concentrations. In nitrate reduction these enzymes received electrons from ferredoxin the K_m of which was 20μM in every case. Antibody prepared against purified nitrate reductase from HM-1 inhibited by more than 80% the nitrate-reducing activity in the extract of each of the five strains. In Ouchterlony's immunodiffusion test, the antibody formed a single precipitation line fusing without spur with the crude extracts from the strains. Such a nitrate reductase as was found in HM-1 seems to be common in species of C. perfringens. Solubilized nitrate reductase from Escherichia coli or Clostridium clostridiiforme extract containing soluble nitrate reductase did not show a cross-reaction, but the enzymatically inactive extracts from HM-1 or DA-7 grown in the presence of tungstate formed a precipitation line fusing with that of the active extracts.