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Poster Presentation 2-35
A New Oxygen Sensitivity in Photosynthetic H2 Production
James W. Lee and Elias Greenbaum
Chemical Sciences Division, Oak Ridge National Laboratory P. O. Box 2008, Oak Ridge, TN 37831-6194
Telephone: (865) 574-1028; Fax: (865) 574-1275; E-mail: leejw@ornl.gov
We have discovered a new competitive pathway for O2 sensitivity in algal H2 production that is distinct from the O2 sensitivity of hydrogenase per se. This O2 sensitivity is apparently linked to the photosynthetic H2 production pathway that is coupled to proton translocation across the thylakoid membrane. Addition of the proton uncoupler FCCP eliminates this mode of O2 inhibition on H2 photoevolution. This newly discovered inhibition is most likely due to background O2 that apparently serves as a terminal electron acceptor in competition with the H2 production pathway for photosynthetically generated electrons from water splitting. This O2-sensitive H2-production electron transport pathway was inhibited by DCMU. Our experiments demonstrated that this new pathway is more sensitive to O2 than the traditionally known O2 sensitivity of hydrogenase. This discovery provides new insight into the mechanism of O2 inactivation of hydrogenase and may contribute to the development of a more efficient and robust system for photosynthetic H2 production.
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