title: Two-site property of thenoyltrifluoroacetone inhibiting succinate-ubiquinone reductase.
abstract: It is proved by using the Dixon plot and the Lineweaver-Burk plot that thenoyltrifluoroacetone (TTFA) has two inhibitive sites affecting the reduction of ubiquinone catalyzed by succinate-ubiquinone reductase. The high affinity site (inhibited at the concentration of thenoyltrifluoroacetone less than 20 mumol/L) shows noncompetitive with substrate Q2, while the low affinity site (inhibited at the concentration of TTFA over 20 mumol/L) shows competitive. It is suggested that both the reducing steps of Q----QH-. and QH-.----QH2 are inhibited by thenoyltrifluoroacetone.
authors.affiliation: Institute of Biophysics, Academia Sinica, Beijing, PRC.
authors.forename: J X
authors.initials: JX
authors.lastname: Xu
authors.forename: T E
authors.initials: TE
authors.lastname: King
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D002417:Cattle; D003067:Coenzymes; D042963:Electron Transport Complex II; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D010088:Oxidoreductases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013385:Succinate Dehydrogenase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013804:Thenoyltrifluoroacetone / Q000494:pharmacology*; D014451:Ubiquinone / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D003067:Coenzymes; D009097:Multienzyme Complexes; D014451:Ubiquinone; D013804:Thenoyltrifluoroacetone; D010088:Oxidoreductases; D042963:Electron Transport Complex II; D013385:Succinate Dehydrogenase; C024989:coenzyme Q10; C003741:ubiquinol