Change in activity of nuclear poly(ADP-ribose) glycohydrolase during the HeLa S3 cell cycle

The change in activity of nuclear poly(ADP-ribose) glycohydrolase during the cell cycle of HeLa S3 cells was investigated. The poly(ADP-ribose) glycohydrolase activity was solubilized from HeLa S3 cell nuclei and chromosomes only by sonication at high ionic strength. The enzyme hydrolyzed poly(ADP-ribose) exoglycosidically, producing ADP-ribose. After release from mitosis, the activity of the solubilized nuclear poly(ADP-ribose) glycohydrolase per nucleus or per unit protein, assayed with 3H]poly(ADP-ribose) (average chain length, n = 15) as substrate, was lowest in the early G1 phase and highest in the late G1 phase. The specific activity in the late G1 phase was about two times that in the early G1 phase. The high activity remained constant during the S-G2-M phase. A similar change during the cell cycle was observed after release from hydroxyurea block. These results suggest that the activity of poly(ADP-ribose) glycohydrolase doubled during the G1 phase of the cell cycle of HeLa S3 cells.