Abstract
The catalytically active form of spinach leaf ribulose-1,5-bisphosphate carboxylase (3-phospho-d-glycerate carboxylase (dimerizing); EC 4.1.1.39) 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 language | English (US) |
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Pages (from-to) | 34-39 |
Number of pages | 6 |
Journal | Biochimica et Biophysica Acta (BBA)/Protein Structure and Molecular |
Volume | 831 |
Issue number | 1 |
DOIs | |
State | Published - Sep 20 1985 |
Keywords
- (Spinach)
- Enzyme crystallization
- Enzyme purification
- Ribulosebisphosphate carboxylase
ASJC Scopus subject areas
- Biophysics
- Structural Biology
- Biochemistry
- Molecular Biology