Rubisco, short for ribulose-1,5-bisphosphate carboxylase/oxygenase, is the enzyme that catalyzes the initial step of carbon fixation during photosynthesis.

In the process of photosynthesis, plants and other autotrophs convert atmospheric carbon dioxide into organic compounds, which serve as vital sources of energy and materials for growth. This transformation, known as carbon fixation, is crucial for sustaining life on Earth. The first step of this process involves rubisco facilitating the reaction between carbon dioxide and ribulose-1,5-bisphosphate (RuBP) to produce two molecules of 3-phosphoglycerate (3-PGA):

Rubisco is regarded as one of the most significant enzymes on our planet, as it is responsible for fixing approximately $10^{11}$ metric tons of carbon each year. However, despite its critical role, rubisco is relatively inefficient. It can also catalyze a reaction between oxygen and RuBP, resulting in the release of carbon dioxide, a phenomenon known as photorespiration. This process can diminish the overall efficiency of photosynthesis by as much as 50%.

Researchers are actively exploring methods to enhance the efficiency of rubisco, as improvements could have substantial implications for agriculture and climate change. By increasing the effectiveness of carbon fixation, it may be possible to boost crop yields and lower atmospheric carbon dioxide levels, thus contributing to the mitigation of climate change effects.