Biochemistry: role of PQQ as a mammalian enzyme cofactor?

Abstract

The announcement by Kasahara and Kato of a new redox-cofactor vitamin for mammals, pyrroloquinoline quinone (PQQ), was based on their claim that an enzyme, predicted to be involved in mouse lysine metabolism, is a PQQ-dependent dehydrogenase. However, this claim was dependent on a sequence analysis using databases that inappropriately label beta-propeller sequences as PQQ-binding motifs. What the evidence actually suggests is that the enzyme is an interesting novel protein that has a seven-bladed beta-propeller structure, but there is nothing to indicate that it is a PQQ-dependent dehydrogenase.