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THE C2 OXIDATIVE PHOTOSYNTHETIC CARBON CYCLE
1Department of Biochemistry, Michigan State University, East Lansing, Michigan 48824-1319.
Annual Review of Plant Physiology and Plant Molecular Biology
|June 1, 1997
Summary
Photosynthetic carbon metabolism involves both C2 and C3 cycles, initiated by Rubisco. This unified process self-regulates to balance CO2 and O2 exchange, influencing atmospheric gas ratios and photosynthesis rates.
Area of Science:
- Biochemistry
- Plant Physiology
Background:
- The C2 oxidative and C3 reductive photosynthetic carbon cycles are fundamental to plant life.
- These cycles involve complex interactions with carbon dioxide (CO2) and oxygen (O2) metabolism.
Purpose of the Study:
- To unify nearly 80 years of research on photosynthetic carbon metabolism.
- To explain the coexistence and self-regulation of C2 and C3 cycles.
Main Methods:
- Review and synthesis of research on O2 inhibition, glycolate metabolism, photorespiration, and CO2 concentrating mechanisms.
- Analysis of the role of Rubisco's oxygenase activity.
Main Results:
- The C2 and C3 cycles coexist and are initiated by Rubisco.
- Both cycles require energy, regenerate RuBP, and regulate CO2/O2 exchange.
- These processes establish net photosynthesis rates and compensation points.
Conclusions:
- Photosynthetic carbon metabolism is a unified process involving both C2 and C3 cycles.
- The self-regulation of these cycles is crucial for maintaining atmospheric gas balance and plant productivity.