Details

Autor(en) / Beteiligte

• Jay, Zackary J.
• Hunt, Kristopher A.
• Chou, Katherine J.
• Schut, Gerrit J.
• Maness, Pin-Ching
• Adams, Michael W.W.
• Carlson, Ross P.

Titel

Integrated thermodynamic analysis of electron bifurcating [FeFe]-hydrogenase to inform anaerobic metabolism and H2 production

Ist Teil von

• Biochimica et biophysica acta. Bioenergetics, 2020-01, Vol.1861 (1), p.148087-148087, Article 148087

Ort / Verlag

Netherlands: Elsevier B.V

Erscheinungsjahr

2020

Quelle

Access via ScienceDirect (Elsevier)

Beschreibungen/Notizen

• Electron bifurcating, [FeFe]-hydrogenases are recently described members of the hydrogenase family and catalyze a combination of exergonic and endergonic electron exchanges between three carriers (2 ferredoxinred− + NAD(P)H + 3 H+ = 2 ferredoxinox + NAD(P)+ + 2 H2). A thermodynamic analysis of the bifurcating, [FeFe]-hydrogenase reaction, using electron path-independent variables, quantified potential biological roles of the reaction without requiring enzyme details. The bifurcating [FeFe]-hydrogenase reaction, like all bifurcating reactions, can be written as a sum of two non-bifurcating reactions. Therefore, the thermodynamic properties of the bifurcating reaction can never exceed the properties of the individual, non-bifurcating, reactions. The bifurcating [FeFe]-hydrogenase reaction has three competitive properties: 1) enabling NAD(P)H-driven proton reduction at pH2 higher than the concurrent operation of the two, non-bifurcating reactions, 2) oxidation of NAD(P)H and ferredoxin simultaneously in a 1:1 ratio, both are produced during typical glucose fermentations, and 3) enhanced energy conservation (~10 kJ mol−1 H2) relative to concurrent operation of the two, non-bifurcating reactions. Our analysis demonstrated ferredoxin E°′ largely determines the sensitivity of the bifurcating reaction to pH2, modulation of the reduced/oxidized electron carrier ratios contributed less to equilibria shifts. Hydrogenase thermodynamics data were integrated with typical and non-typical glycolysis pathways to evaluate achieving the ‘Thauer limit’ (4 H2 per glucose) as a function of temperature and pH2. For instance, the bifurcating [FeFe]-hydrogenase reaction permits the Thauer limit at 60 °C if pH 2 ≤ ~10 mbar. The results also predict Archaea, expressing a non-typical glycolysis pathway, would not benefit from a bifurcating [FeFe]-hydrogenase reaction; interestingly, no Archaea have been observed experimentally with a [FeFe]-hydrogenase enzyme. [Display omitted] •Thermodynamics of electron bifurcating [FeFe]-hydrogenase quantified•Ferredoxin E°′ largely determines sensitivity of [FeFe]-hydrogenase reactions to pH2.•Bifurcating [FeFe]-hydrogenase enhances energy conservation (~10 kJ mol−1 H2).•Archaea expressing a non-typical glycolysis pathway are not be expected to benefit from a bifurcating [FeFe]-hydrogenase.