• Golbeck, John H. (PI)

Project: Research project

Project Details


A genetically-engineered variant of a naturally-occurring photosynthetic reaction center, termed Photosystem I, is chemically linked to a genetically-engineered variant of a naturally-occurring hydrogen producing catalyst, termed hydrogenase, using a molecular wire consisting of 1,6-hexanedithiol. When the Photosystem I-wire-hydrogenase construct is illuminated, hydrogen is produced. In previous work, we have attached the molecular wire to the terminal iron-sulfur cluster, termed FB, of Photosystem I and have achieved rates of hydrogen production that exceed the rate of natural photosynthesis. In this work, we will replace the 1,6-hexanedithiol with a genetically-engineered variant of naturally-occurring dicluster ferredoxin that has outward facing, cysteine residues. The thiol groups on these cysteine residues attach themselves to iron atoms of the FB cluster of the variant Photosystem I and to the distal iron-sulfur of the variant hydrogenase enzyme. The two iron-sulfur clusters in the ferredoxin provide an efficient electron transfer pathway between the two proteins. Our research objectives are to optimize the binding of the variant dicluster ferredoxin so as to produce the highest possible rates of light-induced hydrogen production and to provide additional experimental evidence that the Photosystem I-ferredoxin-hydrogenase construct exists as a stable hydrogen-producing entity. Because this new construct is entirely constructed from proteins, the stage will be set in future work to introduce the genes for these proteins in a living cell and have the internal biochemical machinery construct a Photosystem I-ferredoxin-hydrogenase construct entirely in vivo. In previous work, we also showed that a menaquinone-terminated molecular wire could be attached to the quinone-binding sites of the menB variant of Photosystem I, and that a Pt nanoparticle could be attached to other end of the molecular wire that contains the thiol group. In this work, we will replace the Pt nanoparticle with a variant of a naturally-occurring hydrogenase enzyme that contains a binding site for the molecular wire. We will then optimize the binding so as to produce the highest amount of hydrogen in the light. The core idea behind this part of the project is to extract the electron from a more powerful reductant in Photosystem I - the quinone site instead of the FB cluster - so as to achieve the highest possible efficiency of solar energy conversion to a useful product, hydrogen.
Effective start/end date9/15/169/14/17


  • Basic Energy Sciences: $2,637,480.00


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