- Decreased activities of ubiquinol:ferricytochrome c oxidoreductase (complex III) and ferrocytochrome c:oxygen oxidoreductase (complex IV) in liver mitochondria from rats with hydroxycobalamin[c-lactam]-induced methylmalonic aciduria. Krahenbuhl, S., Chang, M., Brass, E.P., Hoppel, C.L. J. Biol. Chem. (1991)