Minireview The role of electrostatics in proton-conducting membrane protein complexes

Abstract Electrostatic interactions play a key role in the cou-pling of electron and proton transfer in membrane protein com-plexes during the conversion of the energy stored in sunlight orreduced substrates into biochemical energy via a transmembraneelectrochemical proton potential. Principles of charge stabiliza-tion within membrane proteins are reviewed and discussed forphotosynthetic reaction centers, cytochrome c oxidases, and di-heme-containing quinol:fumarate reductases. The impact of X-ray structure-based electrostatic calculations on the functionalinterpretation of these structural coordinates, on providing newexplanations for experimental observations, and for the designof more focused additional experiments is illustrated by a num-ber of key examples.# 2003 Federation of European Biochemical Societies. Pub-lished by Elsevier Science B.V. All rights reserved.Keywords: Cytochromec oxidase;Electrontransfer;Photosyntheticreactioncenter;Protontransfer;Quinol:fumaratereductase1. IntroductionElectrostaticinteractionsplayacentralroleinavarietyofbiologicalprocesses,suchasmolecularrecognition,substratediiusion,catalyticrates,controlbyphosphorylationandpro-teinfolding(reviewed,e.g.,in[1^3]).Inparticular,theyin£u-encebiochemicalpropertiessuchaspK