Activation and regulation of ribulose bisphosphate carboxylase-oxygenase in the absence of small subunits

J Biol Chem. 1979 Oct 25;254(20):10184-9.


Ribulose 1,5-bisphosphate carboxylase from Rhodospirillum rubrum requires CO2 and Mg2+ for activation of both CO2, both the carboxylase and oxygenase activities are stimulated by 6-phoshpo-D-gluconate, fructose 1,6-bisphosphate, 2-phosphoglycolate, 3-phosphoglycerate, NADPH, and fructose 6-phosphate. The carboxylase activity is not activated by ribose 5-phosphate. The substrate, ribulose bisphosphate, neither activates nor inhibits the CO2 and Mg2+ activation of this enzyme. Activation by CO2 and Mg2+ is rapid and results in increased susceptibility to active-site-directed protein modification reagents. Because the R. rubrum carboxylase-oxygenase is a dimer of large subunits and contains no small subunits, these results suggest that the effector binding sites of the higher plant enzyme may also be found on the large subunit.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Bicarbonates / pharmacology
  • Carboxy-Lyases / metabolism*
  • Enzyme Activation
  • Kinetics
  • Magnesium / pharmacology
  • Pyridoxal Phosphate / pharmacology
  • Rhodospirillum rubrum / enzymology*
  • Ribulose-Bisphosphate Carboxylase / metabolism*


  • Bicarbonates
  • Pyridoxal Phosphate
  • Carboxy-Lyases
  • Ribulose-Bisphosphate Carboxylase
  • Magnesium