rubisco

(noun)

(ribulose bisphosphate carboxylase) a plant enzyme which catalyzes the fixing of atmospheric carbon dioxide during photosynthesis by catalyzing the reaction between carbon dioxide and RuBP

Related Terms

Examples of rubisco in the following topics:

  • Regulation of the Calvin Cycle

    • The enzyme that catalyzes this specific reaction is ribulose bisphosphate carboxylase (RuBisCO).
    • RuBisCO is identified as the most abundant enzyme on earth, to date.
    • RuBisCO enzymatic activity is regulated by numerous factors including: ions, RuBisCO activase, ATP/ADP and reduction/oxidation states, phosphate and carbon dioxide.
    • The various factors influencing RuBisCO activity directly affect phase 1 of the Calvin cycle.
    • During the third phase of the Calvin cycle, regeneration of RuBisCO occurs.

  • Carboxysomes

    • These compartments are thought to concentrate carbon dioxide to overcome the inefficiency of RuBisCo (ribulose bisphosphate carboxylase/oxygenase) - the predominant enzyme in carbon fixation and the rate limiting enzyme in the Calvin cycle.
    • Carboxysomes were first purified from Thiobacillus neapolitanus in 1973, and were shown to contain RuBisCo held within a rigid outer covering .
    • The features visualized arise from the distribution of stain around proteins forming the shell as well as around the RuBisCO molecules that fill the carboxysome interior.

  • CAM and C4 Photosynthesis

    • Decarboxylation of malate during the day releases CO2 inside the leaves, thus allowing carbon fixation to 3-phosphoglycerate by RuBisCO.
    • The C4 pathway bears resemblance to CAM; both act to concentrate CO2 around RuBisCO, thereby increasing its efficiency.
    • C4 plants, in contrast, concentrate CO2 spatially, with a RuBisCO reaction centre in a "bundle sheath cell" that is inundated with CO2.
    • Plants that do not use PEP-carboxylase in carbon fixation are called C3 plants because the primary carboxylation reaction, catalyzed by RuBisCO, produces the three-carbon 3-phosphoglyceric acids directly in the Calvin-Benson cycle.

  • The Calvin Cycle

    • In the stroma, in addition to CO2,two other components are present to initiate the light-independent reactions: an enzyme called ribulose bisphosphate carboxylase (RuBisCO) and three molecules of ribulose bisphosphate (RuBP).
    • RuBisCO catalyzes a reaction between CO2 and RuBP.
    • In stage 1, the enzyme RuBisCO incorporates carbon dioxide into an organic molecule, 3-PGA.

  • Intermediates Produced During the Calvin Cycle

    • This process requires the enzyme RuBisCO and both ATP and NADPH.