THE ELECTION TRANSPORT SYSTEM IN NITROGEN FIXATION BY <i>Azotobacter</i> , I. AZOTOFLAVIN AS AN ELECTRON CARRIER

Abstract

A flavoprotein, named azotoflavin, was isolated from an extract of Azotobacter vinelandii cells, which linked the reducing power generated by illuminated spinach chloroplasts to the Azotobacter nitrogen-fixing enzyme complex. The photoreduction of the yellow azotoflavin by chloroplasts produced a stable, free-radical semiquinone, blue in color, with properties similar to those described by other investigators for an Azotobacter flavoprotein of unknown biological function.