家兎 肝 Mg2^+-依存型 ADP-ribose Pyrophosphatase의 精製 및 性狀 = Purification and Properties of Mg2^+-dependent ADP-ribose Pyrophosphatase frorn Rabbit Liver

다국어 초록 (Multilingual Abstract)

Mg^2+ -dependent ADP-ribose pyrophosphatase from rabbit liver, which catalyzes the hydrolysis of ADP-ribose to AMP and ribose-5-phosphate in the presence of Mg^2+, was purified and its properties were characterized.
Mg^2+ -dependent ADP-ribose pyrophosphatase from rabbit liver cytosol was purified 4809-fold to the specific activity of 1491μmoles/hr/mg protein by ammonium sulfate fractionation, pH treatment, pH-gradient, pH-gradient DEAE-cellulose chromatography, Sephadex G-150 gel filtration and preparative isoelectric focusing. The most effective step in the whole purification procedures was pH-gradient DEAE-cellulose chromatography in which the enzyme was purified 30-fold. The enzyme which had pH optimum of 9.5 showed high substrate specificity to ADP-ribose with Km value of 0.12mM, whereas it did not hydrolyze the pyrophosphate bond of ADP, ATP, NAD and NADH, indicating that its true substrate in vivo is ADP-ribose. The isoelectric point of the enzyme measured by preparative isoelectric focusing was pH 4.2, suggesting that the content of acidic amino acids is relatively high in the enzyme protein.