Applegate Amanda M, Lubner Carolyn E, Knörzer Philipp, Happe Thomas, Golbeck John H
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.
Photosynth Res. 2016 Jan;127(1):5-11. doi: 10.1007/s11120-014-0064-y. Epub 2014 Dec 20.
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.
针对先前优化的生物杂交细胞色素c6交联的光系统I（C13G）-1,8-辛二硫醇-[铁铁]-氢化酶（C97G）（光系统I-氢化酶）纳米结构，测量了光诱导产氢的量子产率。光系统I-氢化酶纳米结构的理论量子产率为每吸收一个光子产生0.50个氢分子，这相当于每产生一个氢分子需要两个光子。用400至700纳米的可见光照射光系统I-氢化酶纳米结构，导致每吸收一个光子产生氢分子的平均量子产率为0.10 - 0.15，这相当于每产生一个氢分子需要6.7 - 10个光子。理论量子产率与实验量子产率之间存在差异的一个可能原因是出现了非生产性的光系统I（C13G）-1,8-辛二硫醇-光系统I C13G（光系统I-光系统I）共轭物，它们吸收光但不产生氢。假设硫醇-铁偶联在产生光系统I-光系统I共轭物以及产生光系统I-氢化酶纳米结构方面效率相同，理论量子产率将降至每吸收一个光子产生0.167个氢分子，这相当于每产生一个氢分子需要6个光子。该值接近当前研究中的测量值范围。一种从非生产性的光系统I-光系统I共轭物中纯化光系统I-氢化酶纳米结构或在光系统I和[铁铁]-氢化酶酶位点引入不同化学方法的策略，可能会使光系统I-氢化酶纳米结构接近光诱导产氢的预期理论量子产率。
