5jfc
NADH-dependent Ferredoxin:NADP Oxidoreductase (NfnI) from Pyrococcus furiosus
Structural highlights
FunctionSUDHA_PYRFU A bifunctional enzyme that catalyzes the reduction of elemental sulfur or polysulfide to hydrogen sulfide with NADPH as electron donor. Also functions as a reduced ferredoxin:NADP oxidoreductase with a very high affinity for reduced ferredoxin. Exhibits a broad specificity for various physiological and non-physiological substrates with varied reduction potentials such as methyl viologen, benzyl viologen, FAD, FMN, methylene blue, 2,6-dichlorophenolindophenol (DCIP), cytochrome C and ferricyanide with highest preference for benzyl viologen. Does not reduce fumarate, succinate, nitrate, nitrite, sulfate, sulfite or protons. Does not possess any hydrogenase activity or NADPH-dependent glutamate synthase activity.[1] [2] [REFERENCE:4] Publication Abstract from PubMedThe recently realized biochemical phenomenon of energy conservation through electron bifurcation provides biology with an elegant means to maximize utilization of metabolic energy. The mechanism of coordinated coupling of exergonic and endergonic oxidation-reduction reactions by a single enzyme complex has been elucidated through optical and paramagnetic spectroscopic studies revealing unprecedented features. Pairs of electrons are bifurcated over more than 1 volt of electrochemical potential by generating a low-potential, highly energetic, unstable flavin semiquinone and directing electron flow to an iron-sulfur cluster with a highly negative potential to overcome the barrier of the endergonic half reaction. The unprecedented range of thermodynamic driving force that is generated by flavin-based electron bifurcation accounts for unique chemical reactions that are catalyzed by these enzymes. Mechanistic insights into energy conservation by flavin-based electron bifurcation.,Lubner CE, Jennings DP, Mulder DW, Schut GJ, Zadvornyy OA, Hoben JP, Tokmina-Lukaszewska M, Berry L, Nguyen DM, Lipscomb GL, Bothner B, Jones AK, Miller AF, King PW, Adams MWW, Peters JW Nat Chem Biol. 2017 Apr 10. doi: 10.1038/nchembio.2348. PMID:28394885[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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