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Generation of H 2 O 2 in Brain Mitochondria
Author(s) -
Patole Milind S.,
Swaroop Anand,
Ramasarma T.
Publication year - 1986
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1986.tb02823.x
Subject(s) - mitochondrion , antimycin a , tris , nad+ kinase , biochemistry , succinate dehydrogenase , chemistry , sucrose , glycerol 3 phosphate dehydrogenase , phosphate , glycerol , oxygen , biology , enzyme , organic chemistry
Generation of H 2 O 2 by rat brain mitochondria using succinate and glycerol‐l‐phosphate as substrates has been demonstrated. Earlier workers were unable to detect this activity in sucrose‐Tris buffer. We found that this was due to a lag in the expression of activity in sucrose medium. Using phosphate buffer (50 m M ), good rates are now obtained. Generation of H 2 O 2 by rat brain mitochondria required the presence of antimycin A and was dependent on the substrates succinate and glycerol‐l‐phosphate. Low rates were obtained with NAD + ‐linked substrates and none with choline, glutamate, and NADH. The K m and V max values for H 2 O 2 generation were considerably lower than the corresponding values for the respective dehydrogenase activity, measured by dye reduction. Oxygen‐radical scavengers inhibited H 2 O 2 generation, suggesting oxygen radical involvement. Depletion of ubiquinone from mitochondria resulted in loss of H 2 O 2 generation. Reconstitution of such depleted particles with ubiquinone restored the capacity to generate H 2 O 2 in a concentration‐dependent manner. Levels of H 2 O 2 production were found to be maximal in cerebellum. Brain mitochondria from rabbit, hamster, mouse, and guinea pig also have the capacity to generate H 2 O 2 on oxidation of glycerol‐l‐phosphate.