Characterization of cofactors, substrates and inhibitor binding to flavoenzyme quinone reductase 2 by automated supramolecular nano-electrospray ionization mass spectrometry

► Quinone reductase 2 keeps its oligomeric characteristics during mass spectrometry analyses. ► FAD stoichiometry is precisely determine by native MS. ► Native MS confirms the presence of one zinc atom per QR2 monomer. ► Native MS reveals the binding of inhibitors such as resveratrol and melatonin.