title: Slow passive diffusion of NAD+ between intact isolated plant mitochondria and suspending medium.
abstract: Isolated potato (Solanum tuberosum) tuber mitochondria purified by isopycnic centrifugation in density gradients of Percoll were found to be highly intact, to be devoid of extramitochondrial contaminations and to retain a high rate of O2 consumption. When suspended in a medium that avoided rupture of the outer membrane, intact purified mitochondria progressively lost their NAD+ content by passive diffusion. This led to a slow decrease of oxoglutarate-dependent O2 consumption by isolated mitochondria. Addition of NAD+ to the medium restored the initial State-3 rate of oxoglutarate oxidation. The rate of NAD+ accumulation in the matrix space was concentration-dependent, exhibited Michaelis-Menten kinetics and was strongly inhibited by the analogue N-4-azido-2-nitrophenyl-4-aminobutyryl-NAD+.
mesh_terms: D001386:Azides / Q000378:metabolism; D001692:Biological Transport; D004058:Diffusion; D007425:Intracellular Membranes / Q000378:metabolism; D007656:Ketoglutaric Acids / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D009243:NAD / Q000031:analogs & derivatives / Q000378:metabolism*; D010084:Oxidation-Reduction; D010944:Plants / Q000378:metabolism*; D013367:Submitochondrial Particles / Q000378:metabolism; D013997:Time Factors
chemical_list: D001386:Azides; D007656:Ketoglutaric Acids; D009243:NAD; C040146:N-4-azido-2-nitrophenyl-4-aminobutyryl-NAD