Description
Phosphoenolpyruvate carboxylase is an enzyme in the family of carboxy-lyases found in plants and some bacteria that catalyzes the addition of bicarbonate (HCO3−) to phosphoenolpyruvate (PEP) to form the four-carbon compound oxaloacetate and inorganic phosphate: PEP + HCO3-→ oxaloacetate + Pi. This reaction is used for carbon fixation in CAM (crassulacean acid metabolism) and C4 organisms, as well as to regulate flux through the citric acid cycle (also known as Krebs or TCA cycle) in bacteria and plants. The enzyme structure and its two step catalytic, irreversible mechanism have been well studied. PEP carboxylase is highly regulated, both by phosphorylation and allostery.
Abbr
PEPC (Microorganism)
Applications
This enzyme is useful for enzymatic determination of carbon dioxide when coupled with malate dehydrogenase in clinical analysis.
Appearance
White amorphous powder, lyophilized
Enzyme Commission Number
EC 4.1.1.31
Activity
GradeⅢ 5.0U/mg-solid or more
Contaminants
Lactate dehydrogenase < 1.0×10⁻³% Pyruvate kinase < 0.5%
Molecular Weight
approx. 390 kDa (by gel filtration)
Isoelectric point
6.0±0.1
pH Stability
pH 5.0-8.0 (25°C, 24hr)
Michaelis Constant
1.9×10⁻⁴M (Phosphoenolpyruvate)
Structure
4 Subunits (M.W.100,000) per mole of enzyme
Thermal stability
below 40°C (pH 7.0, 15min)
Stability
Stable at-20°C for at least one year
Stabilizers
BSA, sugar alcohols
Synonyms
PEP carboxylase; PEPCase; PEPC; EC 4.1.1.31; Phosphoenolpyruvate carboxylase; PDB ID: 3ZGE
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