The oxidoreductases catalyse oxido-reductions. The substrate oxidised is
regarded as an hydrogen or electron donor.
The E.C. classification for these enzymes classifies them firstly by the
donor group that undergoes oxidation, then by the
acceptor, and lastly by the enzyme.
The recommended name for these enzymes is dehydrogenase. An
alternative name is reductase. The name oxidase is only
used where O(2) is the acceptor.