Presented at: Solar Energy and Artificial Photosynthesis, The Royal Society, London, 17th-19th July 2007.
and:
Research Frontiers with Rubisco, the "Elexir of Life" in the Biosphere. Rothamsted Research, Harpenden, UK, July 20th - 21st, 2007.
PS 07 14th International Congress of Photosynthesis, Glasgow 2007.
Introduction: Oxygenic life begins with photosynthesis. This process controls CO2 fixation and is responsible for the terrestrial and marine life on the planet. An increase in the global CO2 concentration would have feedbacks on atmospheric temperature, water holding capacity of the atmosphere, and worst of all a decrease in the CO2 holding capacity of oceans, all of which lead to accelerated climate change.
Rubisco is the gatekeeper of the natural process of CO2 sequestration from the atmosphere. The fundamental model of Rubisco kinetics must be sound in order to support all subsequent theories and models that depend on Rubisco kinetics.
Three Kinetic Theories for Rubisco reaction have been discussed over the past three decades:
- Co-limitation Theory (Michaelis-Menten)
- Two-Process Theory (Farquhar, von Caemmerer & Berry, 1980)
- Single-Process, Two-Step Theory (Farazdaghi, 2004)
Of which, the Two-Process theory has been the most widely used.
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Presented at GRC, CO2 Assimilation in Plants:Genome to Biome, Aussois, France, Sept. 11-16, 2005.
Abstract: Rubisco is a Storage/Sink protein, convertible to Enediol, that is the single enzyme for carboxylation. Rubisco-activase assembles the enzyme in light. A theory and model is advanced, introducing the conept that steady state photosynthesis is controlled by two steps. The first step is the synthesis of the enediol enzyme and the second step is carboxylation/oxygenation. It is found that the two-process theory of Farquhar et al is incompatible with the biochemical kinetics of the rubisco reaction. It is shown that photosynthesis is neither limited by Rubisco at low CO2, nor by energy for RuBP regeneration at high CO2.
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