Studies of Redox Cofactor Pyrroloquinoline Quinone and Its Interaction with Lanthanides(III) and Calcium(II)

Recently it was discovered that lanthanides are biologically relevant and found at the centers of many bacterial proteins. Poorly understood, however, is the evolutionary advantage that certain lanthanides might have over calcium at the center of methanol dehydrogenase enzymes bearing redox cofactor PQQ. Here, we present a straightforward method to obtaining clean PQQ from vitamin capsules. Furthermore, we provide full NMR, IR, and UV–vis spectroscopic characterizations of PQQ. We conducted NMR experiments with the stepwise addition of diamagnetic and paramagnetic lanthanides to evaluate the binding to PQQ in solution. This study provides a deeper understanding of PQQ chemistry and its interaction with lanthanides.