Purification and characterization of human meningioma M2-type pyruvate kinase

The M2-type pyruvate kinase was purified from human meningioma by ammonium sulfate precipitation, followed by ion exchange and affinity chromatography. The specific activity of the purified enzyme was 33.4 U/mg with a yield of 6.5%. The enzyme gave a single band with 63,000 +/- 2000 Da upon SDS polyacrylamide gel electrophoresis. On cellulose acetate electrophoresis zymograms, the purified enzyme (M2) showed a single band, while crude extracts gave two broad bands corresponding to pyruvate kinase isozymes. The pI value of purified enzyme was found to be 6.9. With phosphoenol pyruvate as substrate the purified enzyme showed sigmoidal kinetics, while in the presence of 0.6 mM fructose 1,6-diphosphate as modulator it gave a hyperbolic saturation curve with a Km value of 0.53 mM.