title: Quantum yield measurements of light-induced H₂ generation in a photosystem I-[FeFe]-H₂ase nanoconstruct.
abstract: The quantum yield for light-induced H2 generation was measured for a previously optimized bio-hybrid cytochrome c 6-crosslinked PSI(C13G)-1,8-octanedithiol-[FeFe]-H2ase(C97G) (PSI-H2ase) nanoconstruct. The theoretical quantum yield for the PSI-H2ase nanoconstruct is 0.50 molecules of H2 per photon absorbed, which equates to a requirement of two photons per H2 generated. Illumination of the PSI-H2ase nanoconstruct with visible light between 400 and 700 nm resulted in an average quantum yield of 0.10-0.15 molecules of H2 per photon absorbed, which equates to a requirement of 6.7-10 photons per H2 generated. A possible reason for the difference between the theoretical and experimental quantum yield is the occurrence of non-productive PSI(C13G)-1,8-octanedithiol-PSIC13G (PSI-PSI) conjugates, which would absorb light without generating H2. Assuming the thiol-Fe coupling is equally efficient at producing PSI-PSI conjugates as well as in producing PSI-H2ase nanoconstructs, the theoretical quantum yield would decrease to 0.167 molecules of H2 per photon absorbed, which equates to 6 photons per H2 generated. This value is close to the range of measured values in the current study. A strategy that purifies the PSI-H2ase nanoconstructs from the unproductive PSI-PSI conjugates or that incorporates different chemistries on the PSI and [FeFe]-H2ase enzyme sites could potentially allow the PSI-H2ase nanoconstruct to approach the expected theoretical quantum yield for light-induced H2 generation.
authors.affiliation: Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA.
authors.forename: Amanda M
authors.initials: AM
authors.lastname: Applegate
authors.affiliation: Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA.|Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA.
authors.forename: Carolyn E
authors.initials: CE
authors.lastname: Lubner
authors.affiliation: Lehrstuhl für Biochemie der Pflanzen, AG Photobiotechnologie, Ruhr-Universität Bochum, 44780, Bochum, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Knörzer
authors.affiliation: Lehrstuhl für Biochemie der Pflanzen, AG Photobiotechnologie, Ruhr-Universität Bochum, 44780, Bochum, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Happe
authors.affiliation: Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA. jhg5@psu.edu.|Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA. jhg5@psu.edu.
authors.forename: John H
authors.initials: JH
authors.lastname: Golbeck
mesh_terms: D056804:Biofuels; D003432:Cross-Linking Reagents / Q000737:chemistry; D045365:Cytochromes c6 / Q000737:chemistry / Q000378:metabolism; D006859:Hydrogen / Q000378:metabolism*; D006864:Hydrogenase / Q000737:chemistry / Q000378:metabolism; D007501:Iron / Q000737:chemistry / Q000378:metabolism; D008027:Light; D049329:Nanostructures / Q000737:chemistry*; D045331:Photosystem I Protein Complex / Q000737:chemistry / Q000378:metabolism*; D011789:Quantum Theory; D013438:Sulfhydryl Compounds / Q000737:chemistry
chemical_list: D056804:Biofuels; D003432:Cross-Linking Reagents; D045365:Cytochromes c6; D045331:Photosystem I Protein Complex; D013438:Sulfhydryl Compounds; D006859:Hydrogen; D007501:Iron; D006864:Hydrogenase; C516316:1,8-octanedithiol
keywords: Bioconjugate; Biohydrogen; Hydrogenase; Molecular wire; Photosystem I; Photosystem I-hydrogenase; Solar biofuels