The<unk>  is an enzyme that forms part of the electron transport chain in plants, as well as some fungi, protists and possibly some animals. Sequences similar to the plant oxidase have also been identified in bacterial genomes.
The oxidase provides an<unk>  route for electrons passing through the electron transport chain to reduce oxygen. However, as several proton-pumping steps are bypassed in this<unk>  pathway, activation of the oxidase reduces ATP generation. This enzyme was first identified as a distinct oxidase pathway from cytochrome c oxidase as the<unk>  is resistant to inhibition by the poison cyanide.
Alternative oxidase
Caspase
Receptor 
Nitric oxide synthase
Adenylate cyclase
Adenylate kinase
Ubiquinol oxidase
Oxidoreductase