Steady-state kinetics of NADH:coenzyme Q oxidoreductase isolated from bovine heart mitochondria.
Steady-state kinetics of the bovine heart NADH:coenzyme Q oxidoreductase reaction were analyzed in the presence of various concentrations of NADH and coenzyme Q with one isoprenoid unit (Q1). Product inhibitions by NAD+ and reduced coenzyme Q1 were also determined. These results show an ordered sequential mechanism in which the order of substrate binding and product release is Q1-NADH-NAD+-Q1H2. It has been widely accepted that the NADH binding site is likely to be on the top of a large extramembrane portion protruding to the matrix space while the Q1 binding site is near the transmembrane moiety. The rigorous controls for substrate binding and product release are indicative of a strong, long range interaction between NADH and Q1 binding sites.
Nakashima
Yumiko
Y
Department of Life Science, Himeji Institute of Technology and CREST, Japan Science and Technology Corporation, Kamigohri, Akoh Hyogo.
Shinzawa-Itoh
Kyoko
K
Watanabe
Kenji
K
Naoki
Kazuki
K
Hano
Nobuko
N
Yoshikawa
Shinya
S
D000818:Animals; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D042967:Electron Transport Complex I; D025461:Feedback, Physiological; D007700:Kinetics; D008929:Mitochondria, Heart / Q000737:chemistry / Q000201:enzymology*; D008956:Models, Chemical; D009243:NAD / Q000378:metabolism / Q000494:pharmacology; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D010084:Oxidation-Reduction; D011485:Protein Binding; D014451:Ubiquinone / Q000378:metabolism / Q000494:pharmacology
D009243:NAD; D014451:Ubiquinone; D009247:NADH, NADPH Oxidoreductases; D042967:Electron Transport Complex I