(692c) Facilitating Electron Channeling in a Self-Assembling Metabolon Containing Two Dehydrogenases and a Nife-Hydrogenase

To accelerate the electron transport rate for cascade enzymatic production of hydrogen gas, we constructed a self-assembling metabolon (complexed enzyme) containing a three cohesin-containing mini-scaffoldin, two dockerin-containing dehydrogenases, one His-tagged NiFe-hydrogenase, and one bifunctional peptide. This bifunctional peptide had one terminus containing a modified dockerin binding the mini-scaffoldin and the other after chemical modification binding a His-tagged hydrogenase. This new strategy expanded the cohesin-dockerin strategy by using His-tagged proteins directly. The metabolon exhibited an initial reaction rate 12.3 times that of the enzyme mixture at the same enzyme loading based on reduction of oxidized benzyl viologen. The hydrogen generation rate catalyzed by the metabolon was approximately 5.6 times of that of the enzyme mixture. Such reaction rate enhancements suggested strong electron channelling among the adjacent redox enzymes of the metabolon.