title: Inhibition and photoinactivation of the bovine heart mitochondrial F1-ATPase by the cytotoxic agent, dequalinium.
abstract: The bovine heart mitochondrial F1-ATPase is inhibited in the dark by the amphipathic cation, dequalinium, with a I0.5 of about 12 microM at pH 7.5. When illuminated at 350 nm in the presence of 1.7 microM dequalinium, the F1-ATPase is inactivated with a pseudo-first order rate constant of 7.9 X 10(-3) min-1. The apparent Kd of the dequalinium-enzyme complex was estimated to be about 12.5 microM by examining the rate of inactivation of the ATPase with 1.7-16.7 microM dequalinium. ATP, ADP, Pi, and Mg2+, singly or in combination, protected the ATPase against photoinactivation, with Mg2+ plus Pi being the most effective.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002417:Cattle; D003868:Dequalinium / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism; D008929:Mitochondria, Heart / Q000201:enzymology*; D010710:Phosphates / Q000378:metabolism; D010777:Photochemistry; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011806:Quinolinium Compounds / Q000494:pharmacology*
chemical_list: D010710:Phosphates; D011806:Quinolinium Compounds; D000255:Adenosine Triphosphate; D003868:Dequalinium; D006180:Proton-Translocating ATPases; D008274:Magnesium