TY - JOUR
T1 - Oxidation of reduced nicotinamide hypoxanthine dinucleotide phosphate by intact rat liver mitochondria
AU - Tischler, Marc E.
AU - Fisher, Ronald R.
N1 - Funding Information:
This work was supported in part by grants from the University of South Carolina Found for Research and Productive Scholarship and the Research Corporation.
PY - 1973/5/30
Y1 - 1973/5/30
N2 - 1. 1. While intact rat liver mitochondria oxidize external NADPH at an extremely low rate (0.1-0.4 nmole per mg protein per min), reduced nicotinamide hypoxanthine dinucleotide phosphate (NHDPH) is relatively rapidly oxidized (12-13 nmoles per mg protein per min). 2. 2. After sonication, the rate of mitochondrial NHDPH oxidation is increased by 2-fold, and the NADPH oxidation rate is double that of NHDPH. 3. 3. NADPH and NHDPH oxidation is neither coupled to ATP synthesis nor inhibited by rotenone or CN-, but is inhibited under anaerobic conditions. These data indicate that, although molecular oxygen is the ultimate electron acceptor, the respiratory chain is not functional in the oxidation reaction. 4. 4. The NADPH oxidase activity resides in the submitochondrial particle fraction isolated from sonicated mitochondrial preparations. 5. 5. These results are interpreted to indicate the presence of an NADPH oxidase system in rat liver mitochondria which is bound to the inner surface of the inner membrane and independent of the respiratory chain. Further, it is concluded that the inner membrane may be significantly more permeable to NHDPH than to NADPH.
AB - 1. 1. While intact rat liver mitochondria oxidize external NADPH at an extremely low rate (0.1-0.4 nmole per mg protein per min), reduced nicotinamide hypoxanthine dinucleotide phosphate (NHDPH) is relatively rapidly oxidized (12-13 nmoles per mg protein per min). 2. 2. After sonication, the rate of mitochondrial NHDPH oxidation is increased by 2-fold, and the NADPH oxidation rate is double that of NHDPH. 3. 3. NADPH and NHDPH oxidation is neither coupled to ATP synthesis nor inhibited by rotenone or CN-, but is inhibited under anaerobic conditions. These data indicate that, although molecular oxygen is the ultimate electron acceptor, the respiratory chain is not functional in the oxidation reaction. 4. 4. The NADPH oxidase activity resides in the submitochondrial particle fraction isolated from sonicated mitochondrial preparations. 5. 5. These results are interpreted to indicate the presence of an NADPH oxidase system in rat liver mitochondria which is bound to the inner surface of the inner membrane and independent of the respiratory chain. Further, it is concluded that the inner membrane may be significantly more permeable to NHDPH than to NADPH.
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U2 - 10.1016/0005-2728(73)90169-2
DO - 10.1016/0005-2728(73)90169-2
M3 - Article
C2 - 4147454
AN - SCOPUS:0015875076
VL - 305
SP - 199
EP - 205
JO - Biochimica et Biophysica Acta - Bioenergetics
JF - Biochimica et Biophysica Acta - Bioenergetics
SN - 0005-2728
IS - 2
ER -