Sedoheptulose-bisphosphatase

Sedoheptulose-bisphosphatase (SBPase) is an enzyme that plays a crucial role in the photosynthetic carbon fixation process in plants. It is one of the enzymes involved in the Calvin cycle, which is the light-independent phase of photosynthesis.

Function

Sedoheptulose-bisphosphatase catalyzes the dephosphorylation of sedoheptulose 1,7-bisphosphate to sedoheptulose 7-phosphate and inorganic phosphate. This reaction is one of the reversible steps in the Calvin cycle, which regenerates ribulose 1,5-bisphosphate (RuBP) for the fixation of carbon dioxide.

Structure

The structure of SBPase is similar to that of other phosphatases. It is a dimeric enzyme, with each monomer consisting of a large domain and a small domain. The active site of the enzyme is located in the large domain, while the small domain is involved in dimerization.

Role in Photosynthesis

In the Calvin cycle, SBPase is responsible for one of the steps leading to the regeneration of RuBP, which is the molecule that accepts CO2 in the first step of the cycle. Therefore, SBPase plays a critical role in maintaining the efficiency of photosynthesis and, consequently, the growth and productivity of plants.

Clinical Significance

While SBPase is primarily studied in the context of plant biology, it has also been implicated in human health. Some studies suggest that alterations in SBPase activity could be linked to metabolic disorders such as diabetes and obesity.

See Also

• Calvin cycle
• Photosynthesis
• Phosphatase
• Carbon fixation