Although a number of solar biohydrogen systems employing photosystem I (PSI) have been developed, few attain the electron transfer throughput of oxygenic photosynthesis. We have optimized a biological/organic nanoconstruct that directly tethers F B, the terminal [4Fe-4S] cluster of PSI from Synechococcus sp. PCC 7002, to the distal [4Fe-4S] cluster of the [FeFe]-hydrogenase (H 2ase) from Clostridium acetobutylicum. On illumination, the PSI-[FeFe]-H 2ase nanoconstruct evolves H 2 at a rate of 2,200 ± 460 μmol mg chlorophyll -1 h -1, which is equivalent to 105 ± 22 e -PSI -1 s -1. Cyanobacteria evolve O 2 at a rate of approximately 400 μmol mg chlorophyll -1 h -1, which is equivalent to 47 e -PSI -1 s -1, given a PSI to photosystem II ratio of 1.8. The greater than twofold electron throughput by this hybrid biological/organic nanoconstruct over in vivo oxygenic photosynthesis validates the concept of tethering proteins through their redox cofactors to overcome diffusion-based rate limitations on electron transfer.
|Original language||English (US)|
|Number of pages||4|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - Dec 27 2011|
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