We have recently reported the assembly of biological/organic hybrid nanoconstructs that generate H2 in the light (Grimme et al., Dalton Trans., 2009, 10106, Lubner et al., Biochemistry, 2010, 49, 10264). In these constructs, electrons are transferred directly from a photochemical module, Photosystem I (PS I), to a catalytic module, either a Pt nanoparticle (NP) or an [FeFe]-hydrogenase (H2ase), through the use of a covalently attached molecular wire. In neither case are any spectroscopic changes visible that would allow electron transfer to be monitored between the photochemical and catalytic modules. In this study, the catalytic module was replaced with an organic cofactor consisting of 1-(3-thiopropyl)-1′-(methyl)-4,4′- bipyridinium chloride that allowed electron transfer to be measured to a spectroscopically observable marker. EPR and optical spectroscopy showed that the tethered redox cofactor was attached to PS I through the FB cluster of PsaC. Under steady-state illumination, the rate of reduction of the 4,4′-bipyridinium cofactor was comparable to the rate of H2 evolution observed for the PS I - molecular wire - Pt-NP and PS I - molecular wire - [FeFe]-H2ase nanoconstructs. These observations provide proof-of-concept for incorporating a redox cofactor in the molecular wire, thereby setting the stage for monitoring the rate and yield of electron transfer between PS I and the tethered [FeFe]-H2ase.
All Science Journal Classification (ASJC) codes
- Environmental Chemistry
- Renewable Energy, Sustainability and the Environment
- Nuclear Energy and Engineering