**3.3 Regeneration**

The final stage of the Calvin-Benson cycle is the regeneration of RuBP from G3P [30]. This process involves a series of enzyme-catalyzed reactions that convert the remaining G3P molecules into RuBP. Enzymes involved in this stage include triose phosphate isomerase (TPI), aldolase, fructose-1,6-bisphosphatase (FBPase), transketolase (TK), and sedoheptulose-1,7-bisphosphatase (SBPase) [31]. Transketolase and aldolase are responsible for the interconversion of carbon skeletons between different sugar phosphate molecules, while phosphoribulokinase catalyzes the phosphorylation of ribulose-5-phosphate (Ru5P) to RuBP, utilizing ATP as a phosphate donor. Once again, phosphorus plays a critical role in the form of ATP, providing the energy required for RuBP regeneration. The regenerated RuBP can then be used for another round of carboxylation, continuing the cycle [32].
