Crystal forms of CO2/Mg2+-activated and deactivated spinach ribulosebisphosphate carboxylase

Lance Pagliaro, Sarjit Johal

Research output: Contribution to journalArticlepeer-review


The catalytically active form of spinach leaf ribulose-1,5-bisphosphate carboxylase (3-phospho-d-glycerate carboxylase (dimerizing); EC is a ternary complex of enzyme · CO2 · Mg2+. Activation occurs upon incubation of the enzyme with CO2 and Mg2+ at alkaline pH; removal of these ions rapidly dissociates the complex. CO2/Mg2+-activated and nonactivated spinach carboxylases crystallize as tetragonal bipyramids by near-equilibrium vapor diffuson using poly(ethylene glycol) as the precipitant. In contrast, nonequilibrium vapor diffusion with similar solutions and precipitant yielded two different forms of activated and non-activated enzyme. The CO2/Mg2+-activated enzyme crystallized as single, flat-plates by this method, whereas the nonactivated spinach carboxylase grew as tetragonal bipyramids. The flat-plate crystals were catalytically active in the absence of subsequent CO2/Mg2+-activation and retained relatively constant levels of activity for approx. 2000 h of storage at 4°C. The bipyramidal-shaped crystals were competent but inactive without prior activation by CO2 and Mg2+.

Original languageEnglish (US)
Pages (from-to)34-39
Number of pages6
JournalBiochimica et Biophysica Acta (BBA)/Protein Structure and Molecular
Issue number1
StatePublished - Sep 20 1985


  • (Spinach)
  • Enzyme crystallization
  • Enzyme purification
  • Ribulosebisphosphate carboxylase

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology


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