The second coenzyme Q1 binding site of bovine heart NADH: coenzyme Q oxidoreductase.
The rotenone sensitivity of bovine heart NADH: coenzyme Q oxidoreductase (Complex I) depends significantly on coenzyme Q1 concentration. The rotenone-insensitive Complex I reaction in Q1 concentration range above 300 microM indicates an ordered sequential mechanism with Q1 and reduced Q1 (Q1H2) as the initial substrate to bind to the enzyme and the last product to be released from the enzyme product complex, respectively. This is the case in the rotenone-sensitive reaction although both Km and Vmax values of the rotenone-insensitive reaction for Q1 are significantly higher than those of the rotenone-sensitive reaction (Nakashima et al., 2002, J. Bioenerg. Biomemb. 34, 11-19). This rigorous control mechanism between the nucleotide and ubiquinone binding sites strongly suggests that the rotenone-insensitive reaction is also physiologically relevant.
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; D001665:Binding Sites; D002417:Cattle; D042967:Electron Transport Complex I; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066298:In Vitro Techniques; D007700:Kinetics; D009206:Myocardium / Q000201:enzymology; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*; D019906:Nuclear Magnetic Resonance, Biomolecular; D012402:Rotenone / Q000494:pharmacology; D014451:Ubiquinone / Q000378:metabolism*
D004791:Enzyme Inhibitors; D012402:Rotenone; D014451:Ubiquinone; D009247:NADH, NADPH Oxidoreductases; D042967:Electron Transport Complex I; C025203:Ubiquinone Q1