PURIFICATION AND PARTIAL CHARACTERIZATION OF A PYRUVATE OXIDOREDUCTASE FROM THE PHOTOSYNTHETIC BACTERIUM RHODOSPIRILLUM-RUBRUM GROWN UNDER NITROGEN-FIXING CONDITIONS

A pyruvate oxidoreductase with the capacity to support pyruvate-dependent nitrogenase activity in vitro has been purified from the photosynthetic bacterium Rhodospirillum rubrum. The enzyme requires CoA for activity and is irreversibly inactivated by oxygen. The molecular properties and K(m) values for the substrates have been studied. In supporting nitrogenase activity addition of ferredoxin is required. Overall the enzyme is similar to the nif-specific pyruvate:flavodoxin oxidoreductase purified from Klebsiella pneumoniae.