Stability study of Rhodobacter capsulatus ferrocytochrome c2 wild-type and site-directed mutants using hydrogen/deuterium exchange monitored by electrospray ionization mass spectrometry.

To estimate the stability of Rhodobacter capsulatus ferrocytochrome c2 wild-type and site-directed mutants, charge state distributions and hydrogen/deuterium exchange rates were monitored by electrospray ionization mass spectrometry. The relative stability of the mutants was observed with the order: V11 insert > Y75F > wild-type = K32E > K12D = K14E > or = K52E > K14E/K32E > W67Y > P35A > I57N > G34S. (A preliminary account has been presented for mutants G34S and P35A [Jaquinod et al. (1995) Rapid Commun. Mass Spectrom. 9, 1135-1140].) This approach is shown to be a useful tool for rapid characterization of mutational effects on protein conformation.