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Kinetics and Mechanism of Mineral Respiration: How Iron Hemes Synchronize Electron Transfer Rates
Author(s) -
Chabert Valentin,
Babel Lucille,
Füeg Michael P.,
Karamash Maksym,
Madivoli Edwin S.,
Herault Nelly,
Dantas Joana M.,
Salgueiro Carlos A.,
Giese Bernd,
Fromm Katharina M.
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201914873
Subject(s) - geobacter sulfurreducens , electron transfer , electron transport chain , chemistry , geobacter , kinetics , anaerobic respiration , biophysics , heme , extracellular , oxidizing agent , inorganic chemistry , anaerobic exercise , photochemistry , biochemistry , bacteria , biology , organic chemistry , biofilm , physiology , physics , genetics , enzyme , quantum mechanics
Anaerobic microorganisms of the Geobacter genus are effective electron sources for the synthesis of nanoparticles, for bioremediation of polluted water, and for the production of electricity in fuel cells. In multistep reactions, electrons are transferred via iron/heme cofactors of c‐type cytochromes from the inner cell membrane to extracellular metal ions, which are bound to outer membrane cytochromes. We measured electron production and electron flux rates to 5×10 5 e s −1 per G. sulfurreducens. Remarkably, these rates are independent of the oxidants, and follow zero order kinetics. It turned out that the microorganisms regulate electron flux rates by increasing their Fe 2+ /Fe 3+ ratios in the multiheme cytochromes whenever the activity of the extracellular metal oxidants is diminished. By this mechanism the respiration remains constant even when oxidizing conditions are changing. This homeostasis is a vital condition for living systems, and makes G. sulfurreducens a versatile electron source.