Insights from the structure of the yeast cytochrome bc(1) complex: crystallization of membrane proteins with antibody fragments

The ubiquinol:cytochrome c oxidoreductase (EC 1.20.2.2, QCR or cytochrome b e, complex) is a component of respiratory and photosynthetic electron trans fer chains in mitochondria and bacteria. The complex transfers electrons fr om quinol to cytochrome c. Electron transfer is coupled to proton transloca tion across the lipid bilayer, thereby generating an electrochemical proton gradient, which conserves the free energy of the redox reaction. The yeast complex was crystallized with antibody Fv fragments, a promising technique to obtain well-ordered crystals from membrane proteins. The high-resolutio n structure of the yeast protein reveals details of the catalytic sites of the complex, which are important for electron and proton transfer. (C) 2001 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.