Direct evidence for the presence of two external NAD(P)H dehydrogenases coupled to the electron transport chain in plant mitochondria.
Exogenous NADPH oxidation by purified mitochondria from both potato tuber and Arum maculatum spadix was completely and irreversibly inhibited by sub-micromolar diphenyleneiodonium (DPI), while exogenous NADH oxidation was inhibited to only a small degree. Addition of DPI caused the collapse of the membrane potential generated by NADPH oxidation, while the potential generated by NADH was unaffected. We conclude that there are two distinct enzymes on the outer surface of the inner membrane of plant mitochondria, one specific for NADH, the other relatively specific for NADPH, with both enzymes linked to the electron transport chain.
Roberts
T H
TH
Department of Plant Physiology, Lund University, Sweden.
Fredlund
K M
KM
Møller
I M
IM
D000968:Antimycin A / Q000494:pharmacology; D001665:Binding Sites; D004579:Electron Transport; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D008928:Mitochondria / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D009245:NADH Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009249:NADP / Q000378:metabolism; D009252:NADPH Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009861:Onium Compounds / Q000494:pharmacology; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000187:drug effects; D010944:Plants / Q000378:metabolism; D011198:Solanum tuberosum / Q000378:metabolism
D004791:Enzyme Inhibitors; D009861:Onium Compounds; D009243:NAD; D009249:NADP; D000968:Antimycin A; C007517:diphenyleneiodonium; D009252:NADPH Dehydrogenase; D009245:NADH Dehydrogenase