PURIFICATION AND PARTIAL CHARACTERIZATION OF A PHOSPHATASE ON THYKOID MEMBRANE IN IPOMOEA AQUATICA

A phosphatase was isolated from the chloroplast thylakoid membrane of Ipomoea aquatica by NaCl extration, ammonium sulfate precipitation, ion-exchange chromatography and hydrophic chromatography through Butyl-Toyopearl 650M column. The results from SDS-PAGE showed that the enzyme was a protein with molecular weight ( M r) of 14.9×10 3 . This phosphatase catalyzed hydrolysis of phosphate monoesters pNPP and had a K m of 1.76×10 -6 mol/L. The pH 5 was optimal for the enzyme reaction, indicating it belonged to acid phosphatase, while the optimal temperature of enzyme catalysis was 50 ℃, suggesting it was thermostable. EDTA and NaF inhibited the enzyme activity intensively, however, it was obviously that no effect of NaCl was found on the phosphatase activity. Fig 6, Tab 3, Ref 24