RuBP, or ribulose biphosphate, is a crucial 5-carbon sugar involved in the first major step of the Calvin cycle in photosynthesis. It acts as the initial carbon dioxide acceptor.
RuBP and Carbon Fixation
RuBP's role in carbon fixation is pivotal:
- Carbon Dioxide Entry: Carbon dioxide (CO2) enters the Calvin cycle.
- Rubisco's Role: The enzyme Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase) catalyzes the reaction between RuBP and CO2. According to the provided reference, carbon dioxide is fixed by Rubisco to RuBP.
- Immediate Breakdown: The resulting 6-carbon compound is unstable and immediately breaks down into two 3-carbon molecules of phosphoglycerate (PGA). This is the first stable product of carbon fixation.
In summary, RuBP is essential for initiating the process of converting inorganic carbon dioxide into organic molecules during photosynthesis.
