Nitrous oxide reductase ofFlexibacter canadensis: a unique membrane-bound enzyme

The subcellular distribution of nitrous oxide reductase was studied in the gliding soil bacterium Flexibacter canadensis. Nitrous oxide reductase activity, as measured by the methyl viologen-nitrous oxide oxidoreductase assay, was associated entirely with the membrane fraction of cell-free extracts. The enzyme was liberated from the membranes with use of detergents but not by high-salt concentrations, thus implying that nitrous oxide reductase is an integral membrane protein. The nitrous oxide reductase of F. canadensis is the first reported example of a membrane-bound form of this respiratory enzyme.