Calvin-Benson cycle (CBC)

The Calvin-Benson cycle, also known as the reductive pentose phosphate cycle, is a series of biochemical reactions occurring in the stroma of chloroplasts in photosynthetic organisms [1]. It represents the primary biological mechanism for carbon fixation, utilizing the chemical energy of ATP and NADPH to convert atmospheric carbon dioxide into organic compounds, specifically glyceraldehyde-3-phosphate [2]. The cycle is divided into three fundamental stages: the carboxylation of ribulose-1,5-bisphosphate (RuBP) by the enzyme RuBisCO, the reduction of 3-phosphoglycerate, and the regeneration of the RuBP acceptor molecule [3]. Due to its absence in animal cells, the cycle is not utilized as a therapeutic target for human diseases, but it is of paramount importance in agricultural biotechnology and herbicide development [4]. Specific chemical inhibitors and herbicides, such as 2-carboxyarabinitol 1,5-bisphosphate, target key enzymes within the cycle to effectively arrest plant growth and development [5]. Beyond weed control, current research focuses on bioengineering the cycle to enhance the efficiency of RuBisCO and other limiting enzymes to improve global crop yields and mitigate climate change through accelerated carbon sequestration [1,4]. Consequently, while the cycle lacks direct clinical application in human medicine, its regulation remains vital for environmental stability, global food security, and the maintenance of the atmospheric carbon balance [2]. [1] Bassham JA, et al. (1954) J Biol Chem; [2] Berg JM, et al. (2002) Biochemistry; [3] Sharkey TD. (2019) Photosynth Res; [4] Raines CA. (2003) Photosynth Res; [5] Gutteridge S, et al. (2003) Essays Biochem.

Other names

Calvin cycleCalvin-Benson-Bassham cycleC3 cycleReductive pentose phosphate cycleCBB cycle

Inhibition of cycle-specific enzymes such as Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) or phosphoribulokinase, thereby halting the assimilation of carbon dioxide and the synthesis of triose phosphates.