| Abstract |
The presence of polyphosphate phosphohydrolase (PPPH) and tripolyphosphate phosphohydrolase (TPPH) in Chlorella ellipsoidea were confirmed from the cell-free extract of the algal cells and three forms of PPPH were isolated, purified, and measured Km-Vmax value and inhibitory effect by metal ions, respectively. PPPH was most active at pH7.2, whereas TPPH at pH 7.6. Both enzymes exhibited their maximum activity at 37℃. For the manifestation of catalytic activity, divalent, divalent metal ions are needed, and the best activator for both enzymes was Co^++ ions (10^-3M). These enzymes were inhibited by Hg^++ ions (10^-3M) considerably. PPPH from Chlorella ellipsoidea was purified by ammonium sulfate fractionation, ion-exchange chromatography on DEAE-Sephadex A-25, and gel filtration on Sephadex G-100, and some properties of the three different fraction with PPPH activity (PPPH₁, PPPH₁, and PPPH₃) were found, i.e, PPPH has multiple form. The Km values of PPPH₁, PPPH₁, and PPPH₃obstained were 6.25 × 10^-4M, and 3.33 × 10^-4M, and Vmax were 3.33 mM/min, 3.33 mM/min, and 2.67 mM/min, respectively. It was shown that the types of inhibition of Hg^++ on the activities of three forms of PPPH were competitive inhibition. |
