title: Effect of the side chain structure of coenzyme Q on the steady state kinetics of bovine heart NADH: coenzyme Q oxidoreductase.
abstract: Steady state kinetics of bovine heart NADH: coenzyme Q oxidoreductase using coenzyme Q with two isoprenoid unit (Q2) or with a decyl group (DQ) show an ordered sequential mechanism in which the order of substrate binding and product release is NADH-Q2 (DQ) -Q2H2 (DQH2)-NAD+ in contrast to the order determined using Q1 (Q1-NADH-NAD(+)-Q1H2) (Nakashima et al., J. Bioenerg. Biomembr. 34, 11-19, 2002). The effect of the side chain structure of coenzyme Q suggests that NADH binding to the enzyme results in a conformational change, in the coenzyme Q binding site, which enables the site to accept coenzyme Q with a side chain significantly larger than one isoprenoid unit. The side chains of Q2 and DQ bound to the enzyme induce a conformational change in the binding site to stabilize the substrate binding, while the side chain of Q1 (one isoprenoid unit) is too short to induce the conformational change.
mesh_terms: D000478:Alkylation; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D042967:Electron Transport Complex I / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D009206:Myocardium / Q000201:enzymology* / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D013379:Substrate Specificity; D013729:Terpenes; D014451:Ubiquinone / Q000737:chemistry*
chemical_list: D013729:Terpenes; D014451:Ubiquinone; D042967:Electron Transport Complex I