Hydrogenase-Catalyzed H2 Production

The last step in the photosynthetic algal H2 production process occurs with the sequential transfer of two negative charges from reduced ferredoxin to a soluble [FeFe] hydrogenase,98,216 which is almost isoenergetic (A/hi = 0.020)11 with ferre 

Besides water oxidation, endogenous substrate (such as starch) catabolism can al so generate reductants for the algal photosynthetic electron transport chain at the 

Maria L. Ghirardi, Pin Ching Maness, and Michael Seibert 

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Hambourger M, Gervaldo M, Svedruzic D, King PW, Gust D, Ghirardi M, Moore AL, Moore TA (2008) [FeFe]-hydrogenase-catalyzed H2 production in a photoelectrochemical biofuel cell. J Am Chem Soc 130 2015-2022... 

Hambouiger, M., Gervaldo, M., Svedruzic, D., King, P. W, Gust, D., Ghirardi, M., et al. (2008). [FeFej-hydrogenase-catalyzed H2 production in a photoelectrochemical biofuel cell. Journal of the American Chemical Society, 130, 2015-2022. http //dx.doi.org/10.1021/ja077691k. 

Cyanobacteria may possess several enzymes directly involved in H2 metabolism nitrogenase(s) catalyzing the production of H2 concomitantly with the reduction of nitrogen to ammonia, an uptake hydrogenase, catalyzing the consumption of H2 produced by the nitrogenase, and a bidirectional hydrogenase, which has the capacity to both take up and produce H2 [3, 5],... 

In the same year, Evans and coworkers reported the electrochemical reduction of protons to H2 catalyzed by the sulfur-bridged dinuclear iron complex 25 as a hydrogenase mimic in which acetic acid was used as a proton source [201]. The proposed mechanism for this reaction is shown in Scheme 60. The reduction of 25 readily affords 25 via a one electron reduction product 25. Protonation... 

As discussed previously, superelectrophilic activation in biological systems has been found even with a metal-free hydrogenase enzyme found in methanogenic archea, an enzymatic system that converts CO2 to methane.57 It was found that /V5./V10-menthyl tetrahydromethanopterin (42) undergoes an enzyme-catalyzed reaction with H2 by hydride transfer to the pro-R position and release of a proton to form the reduced product (43 eq 36). 

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