title: Internalization of the spin-labelled surface potential probe CAT12 by energized mitochondria.
abstract: Rat liver mitochondria briefly incubated in the presence of 50 microM 4-(dodecyl dimethyl ammonium)-1-oxyl-2,2,6,6-tetramethyl piperidine bromide (CAT12) bind 1.9 nmol of this spin-labelled membrane probe per mg mitochondrial protein in a form which is not reducible by ascorbate. Upon energization with ATP the amount of the non-reducible CAT12 increases by about 37%. It is concluded that CAT12 which is not reducible by externally added ascorbate is bound to the inner surface of the inner mitochondrial membrane and/or accumulated in the matrix compartment. Therefore, CAT12 is not suitable to monitor the surface potential of mitochondria and other organelles which develop a transmembrane potential, negative inside.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D003497:Cyclic N-Oxides / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism; D008930:Mitochondria, Liver / Q000378:metabolism*; D051381:Rats; D013113:Spin Labels / Q000378:metabolism*; D013997:Time Factors
chemical_list: D003497:Cyclic N-Oxides; D013113:Spin Labels; C031723:4-(dodecyldimethylammonium)-1-oxyl-2,2,6,6-tetramethylpiperidine; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D000255:Adenosine Triphosphate; D001205:Ascorbic Acid