Studies of pyrroloquinoline quinone species in solution and in lanthanide-dependent methanol dehydrogenases

in addition to water adducts and in complex with lanthanides) with NMR and UV-Vis spectroscopy as well as time-resolved laser-induced fluorescence spectroscopy (TRLFS). Using a europium derivative from a new, recently-discovered class of lanthanide-dependent methanol dehydrogenase (MDH) enzymes, we utilized two techniques to monitor Ln binding to the active sites of these enzymes. Employing TRLFS, we were able to follow Eu(III) binding directly to the active site of MDH using its luminescence and could quantify three Eu(III) states: Eu(III) in the active site of MDH, but also in solution as PQQ-bound Eu(III) and in the aquo-ion form. Additionally, we used the antenna effect to study PQQ and simultaneously Eu(III) in the active site.