Biochemistry, Biophysics, and Structural Biology Commons^™

Distinct Properties Underlie Flavin-Based Electron Bifurcation In A Novel Electron Transfer Flavoprotein Fixab From Rhodopseudomonas Palustris, H. Diessel Duan, Carolyn E. Lubner, Monika Tokmina-Lukaszewska, George H. Gauss, Brian Bothner, Paul W. King, John W. Peters, Anne-Frances Miller

Chemistry Faculty Publications

A newly recognized third fundamental mechanism of energy conservation in biology, electron bifurcation, uses free energy from exergonic redox reactions to drive endergonic redox reactions. Flavin-based electron bifurcation furnishes low-potential electrons to demanding chemical reactions, such as reduction of dinitrogen to ammonia. We employed the heterodimeric flavoenzyme FixAB from the diazotrophic bacterium Rhodopseudomonas palustris to elucidate unique properties that underpin flavin-based electron bifurcation. FixAB is distinguished from canonical electron transfer flavoproteins (ETFs) by a second FAD that replaces the AMP of canonical ETF. We exploited near-UV–visible CD spectroscopy to resolve signals from the different flavin sites in FixAB and to …