title: Redox-coupled protonation of respiratory complex I: the hydrophilic domain.
abstract: Respiratory complex I, NADH:ubiquinone oxidoreductase, is a large and complex integral membrane enzyme found in respiring bacteria and mitochondria. It is responsible in part for generating the proton gradient necessary for ATP production. Complex I serves as both a proton pump and an entry point for electrons into the respiratory chain. Although complex I is one of the most important of the respiratory complexes, it is also one of the least understood, with detailed structural information only recently available. In this study, full-finite-difference Poisson-Boltzmann calculations of the protonation state of respiratory complex I in various redox states are presented. Since complex I couples the oxidation and reduction of the NADH/ubiquinone redox couple to proton translocation, the interaction of the protonation and redox states of the enzyme are of the utmost significance. Various aspects of complex I function are presented, including the redox-Bohr effect, intercofactor interactions, and the effects of both the protein dielectric and inclusion of the membrane.
authors.affiliation: Department of Chemistry, University of California, Davis, California, USA.
authors.forename: Vernon
authors.initials: V
authors.lastname: Couch
authors.forename: Dragan
authors.initials: D
authors.lastname: Popovic
authors.forename: Alexei
authors.initials: A
authors.lastname: Stuchebrukhov
mesh_terms: D003198:Computer Simulation; D004560:Electricity; D042967:Electron Transport Complex I / Q000737:chemistry* / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D007506:Iron-Sulfur Proteins / Q000378:metabolism; D007526:Isoelectric Point; D008958:Models, Molecular; D009010:Monte Carlo Method; D010084:Oxidation-Reduction; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011522:Protons; D013816:Thermodynamics; D016963:Thermus thermophilus / Q000378:metabolism
chemical_list: D007506:Iron-Sulfur Proteins; D011522:Protons; D042967:Electron Transport Complex I