Inhibition of the mitochondrial phosphate carrier by a reaction with a carboxyl group reagent.
The effect of N-ethyl-5-phenylisoxazolium 3"-sulfonate (Woodward's reagent K, WRK), a reagent forming covalent bonds with protein carboxyl groups, on the activity of the mitochondrial phosphate carrier was investigated. Treatment with WRK of mitochondria or of extracted carrier incorporated into liposomes, inhibited phosphate transport in a reconstituted liposomal system. Increasing the binding of WRK resulted in increased inhibition: the modified carrier protein showed a reduced affinity for phosphate, but binding of WRK had no effect on the Vmax of phosphate transport. It was concluded that WRK caused a conformational change in the carrier protein not involving the phosphate or H+ carrier sites such that its affinity for phosphate was lowered.
Wolf
G
G
Department of Pharmaco-Biology, University of Bari, Italy.
Genchi
G
G
Palmieri
F
F
D000818:Animals; D001667:Binding, Competitive; D001692:Biological Transport / Q000187:drug effects; D001894:Borohydrides; D002352:Carrier Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D002417:Cattle; D007202:Indicators and Reagents; D007555:Isoxazoles / Q000494:pharmacology*; D008081:Liposomes; D008929:Mitochondria, Heart / Q000187:drug effects / Q000378:metabolism*; D010080:Oxazoles / Q000494:pharmacology*; D028044:Phosphate-Binding Proteins; D010710:Phosphates / Q000378:metabolism*
D001894:Borohydrides; D002352:Carrier Proteins; D007202:Indicators and Reagents; D007555:Isoxazoles; D008081:Liposomes; D010080:Oxazoles; D028044:Phosphate-Binding Proteins; D010710:Phosphates; C009686:N-ethyl-5-phenylisoxazolium-3'-sulfonate; C025364:sodium borohydride