Although the terminal respiratory chain of Azotobacter has been the subject of several recent studies, the nature of the cytochrome oxidase portion is still somewhat obscure. Repaske (1) partially purified and characterized a soluble succinic dehydrogenase and succinoxidase system from Azotobacter z&elan&i. Wilson and Wilson (2) studied the soluble succinoxidase in Repaske’s preparation and dem...