Pulse radiolysis of methoxatin and methoxatin dependent methylamine dehydrogenase

Using the pulse radiolysis technique the authors have generated in aqueous solution the 1-electron reduced semiquinone forms of the orthoquinone methoxatin [MTX] and of two methoxatin analogues (1,7- and 1,10-phenanthroline-5,6-dione [1,7-PD and 1,10-PD]), and they have measured their visible spectra. From the dependence of these spectra on pH, they estimate pK/sub a/ associated with these semiquinones of 6.8 (0.1) and 4.7 (0.3) for MTX, 6.2 (0.1) for 1.7-PD and 5.1 (0.2) for 1,10-PD. The authors also present initial methoxatin semiquinone spectra obtained in pulse radiolysis studies of methylamine dehydrogenase, a protein isolated from the unclassified bacterium W3A1 that appears to utilize MTX in the catalysis of primary amine oxidation