To further characterize the DOPA species, we performed intact native protein mass spectrometry on F121Y/DOPA SyrB2. This analysis would reveal which ligands, if any, were bound in the proteins. Representative mass spectra of F121Y/DOPA SyrB2 is illustrated in Fig S4 . Algorithmic deconvolution of these peaks reveal the masses of the intact SyrB2 F121Y/DOPA protein (Fig