Generation of hydrogen peroxide by brown adipose tissue mitochondria.

This is the first report on the generation of H2O2 by brown adipose tissue mitochondria. Flavin dehydrogenase-linked substrates like succinate, glycerol-1-phosphate, and fatty acyl CoA were good substrates for the reaction, while NAD+-linked substrates were less effective. In cold-acclimated animals the activity showed a substantial increase (2.5-fold). The Km and Vmax of the reaction were considerably lower than those of the respective dehydrogenase. Metal ions, particularly Cu2+ and Fe2+ were potent inhibitors of the reaction. Nucleoside diphosphates, which were inhibitors by themselves, potentiated the inhibitory action of Fe2+ ions. In most of the properties, the H2O2 generator of brown adipose tissue mitochondria resembled that of liver mitochondria.