Structures and proton-pumping strategies of mitochondrial respiratory enzymes.
Enzymes of the mitochondrial respiratory chain serve as proton pumps, using the energy made available from electron transfer reactions to transport protons across the inner mitochondrial membrane and create an electrochemical gradient used for the production of ATP. The ATP synthase enzyme is reversible and can also serve as a proton pump by coupling ATP hydrolysis to proton translocation. Each of the respiratory enzymes uses a different strategy for performing proton pumping. In this work, the strategies are described and the structural bases for the action of these proteins are discussed in light of recent crystal structures of several respiratory enzymes. The mechanisms and efficiency of proton translocation are also analyzed in terms of the thermodynamics of the substrate transformations catalyzed by these enzymes.
Schultz
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Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125, USA.
Chan
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D000818:Animals; D004579:Electron Transport; D042967:Electron Transport Complex I; D042963:Electron Transport Complex II; D014450:Electron Transport Complex III / Q000737:chemistry; D008928:Mitochondria / Q000201:enzymology*; D008954:Models, Biological; D008956:Models, Chemical; D008958:Models, Molecular; D009097:Multienzyme Complexes / Q000737:chemistry; D009247:NADH, NADPH Oxidoreductases / Q000737:chemistry; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry; D010101:Oxygen Consumption; D006180:Proton-Translocating ATPases / Q000737:chemistry*; D011522:Protons; D013385:Succinate Dehydrogenase / Q000737:chemistry; D013816:Thermodynamics
D009097:Multienzyme Complexes; D011522:Protons; D010088:Oxidoreductases; D042963:Electron Transport Complex II; D013385:Succinate Dehydrogenase; D009247:NADH, NADPH Oxidoreductases; D006180:Proton-Translocating ATPases; D042967:Electron Transport Complex I; D014450:Electron Transport Complex III