Properties of poly(ADP-ribose) glycohydrolase purified from pig testis nuclei

A poly(ADP-ribose) glycohydrolase was purified more than 5,000-fold to apparent homogeneity from pig testis nuclei with a yield of 16%. A protein band, whose molecular mass (Mr) was estimated to be 58,000, detected by SDS-polyacrylamide gel electrophoresis of the purified preparation, was shown to have glycohydrolase activity upon assay by the renaturation method. A native Mr of 51,000 was determined by gel permeation. This polypeptide is a basic protein with a pI value of 8.8. The mode of hydrolysis of poly(ADP-ribose) [(ADP-ribose)n] by this enzyme is exoglycosidic, yielding ADP-ribose as the final product. The Km value for (ADP-ribose)n (average chain length, n = 15) is 5.4 microM and the Vmax of its hydrolysis is 34.5 micromol x min(-1) x mg protein(-1). The optimum pH for enzyme activity is 7.2. Low concentrations (50 approximately 150 mM) of monovalent salts stimulate the enzyme activity. The poly(ADP-ribose) glycohydrolase present in pig testis nuclei has some properties different from either nuclear poly(ADP-ribose) glycohydrolase (type I) or cytoplasmic poly(ADP-ribose) glycohydrolase (type II), purified previously from several tissues including pig thymus, guinea pig liver, calf thymus, human erythrocytes, and placenta. These differences suggest the tissue specificity of poly(ADP-ribose) glycohydrolase.