Pyrroloquinoline quinone: a new redox cofactor in eukaryotic enzymes.

During the past decade pyrroloquinoline quinone has been shown to be a new redox cofactor for a range of bacterial alcohol dehydrogenases. Recent studies suggest that this cofactor may also be covalently bound to the active site of the eukaryotic copper amine oxidases. In this mini-review we present the evidence in support of pyrroloquinoline quinone as a novel eukaryotic cofactor. As a result of mechanistic advances during the last three years, together with a re-examination of previously existing data, a working model for the role of pyrroloquinoline quinone in enzyme-catalyzed amine oxidation reactions can be proposed.