Th. Roberts et al., DIRECT EVIDENCE FOR THE PRESENCE OF 2 EXTERNAL NAD(P)H DEHYDROGENASESCOUPLED TO THE ELECTRON-TRANSPORT CHAIN IN PLANT-MITOCHONDRIA, FEBS letters, 373(3), 1995, pp. 307-309
Exogenous NADPH oxidation by purified mitochondria from both potato tu
ber and Arum maculatum spadix was completely and irreversibly inhibite
d by sub-micromolar diphenyleneiodonium (DPI), while exogenous NADH ox
idation was inhibited to only a small degree. Addition of DPI caused t
he collapse of the membrane potential generated by NADPH oxidation, wh
ile the potential generated by NADH was unaffected, We conclude that t
here are two distinct enzymes on the outer surface of the inner membra
ne of plant mitochondria, one specific for NADH, the other relatively
specific for NADPH, with both enzymes linked to the electron transport
chain.