Figure 1: Schematics of electron transport chains.
From: Photobiocatalytic chemistry of oxidoreductases using water as the electron donor
Representation of the traditional electron transport chain to supply monooxygenases (a) and reductases (for example, alcohol dehydrogenases or old yellow enzymes) (b) with reducing equivalents. In both cases, a high-energy content cosubstrate is oxidized by a regeneration enzyme thereby regenerating the reduced nicotinamide cofactor (NADH or NADPH). The latter delivers two electrons either directly to the production enzyme (for example, alcohol dehydrogenases, old yellow enzymes but also some monooxygenases) or (as in case of many monooxygenases) indirectly via an electron mediator system (such as flavins or FeS-proteins). The flow of electrons is shown in blue. Typical examples for regeneration enzymes comprise formate dehydrogenase, alcohol dehydrogenase, glucose dehydrogenase and so on oxidizing the respective cosubstrates such as formic acid, ethanol/isopropanol or glucose.
