초록
<P> 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 <I>Synechococcus</I> sp. PCC 7002, to the distal [4Fe-4S] cluster of the [FeFe]-hydrogenase (H 2 ase) from <I>Clostridium acetobutylicum</I> . On illumination, the PSI-[FeFe]-H 2 ase nanoconstruct evolves H 2 at a rate of 2,200 ± 460 <I>μ</I> mol mg chlorophyll <SUP>-1</SUP> h <SUP>-1</SUP> , which is equivalent to 105 ± 22 e <SUP>-</SUP> PSI <SUP>-1</SUP> s <SUP>-1</SUP> . Cyanobacteria evolve O 2 at a rate of approximately 400 <I>μ</I> mol mg chlorophyll <SUP>-1</SUP> h <SUP>-1</SUP> , which is equivalent to 47 e <SUP>-</SUP> PSI <SUP>-1</SUP> s <SUP>-1</SUP> , 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. </P>