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Biochemistry, Biophysics, and Structural Biology Commons

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Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

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 Feb 2018

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 ...


Informing Efforts To Develop Nitroreductase For Amine Production, Anne-Frances Miller, Jonathan T. Park, Kyle L. Ferguson, Warintra Pitsawong, Andreas S. Bommarius Jan 2018

Informing Efforts To Develop Nitroreductase For Amine Production, Anne-Frances Miller, Jonathan T. Park, Kyle L. Ferguson, Warintra Pitsawong, Andreas S. Bommarius

Chemistry Faculty Publications

Nitroreductases (NRs) hold promise for converting nitroaromatics to aromatic amines. Nitroaromatic reduction rate increases with Hammett substituent constant for NRs from two different subgroups, confirming substrate identity as a key determinant of reactivity. Amine yields were low, but compounds yielding amines tend to have a large π system and electron withdrawing substituents. Therefore, we also assessed the prospects of varying the enzyme. Several different subgroups of NRs include members able to produce aromatic amines. Comparison of four NR subgroups shows that they provide contrasting substrate binding cavities with distinct constraints on substrate position relative to the flavin. The unique architecture ...