Figure 1.

Synthesis and degradation of poly(ADP-ribose) (PAR) by pure poly(ADP-ribose) polymerase (PARP-1) and poly(ADP-ribose) glycohydrolase (PARG). (a) Time-dependent incorporation of radioactivity from ³H-NAD into trichloroacetic acid (TCA)-precipitated proteins in the absence or presence of 30 μM phenanthridinone (PHE; a PARP-1 inhibitor) at time 0 or 60 min. (b) Effect of pure PARG (0.05 U) added after 60 min on incorporation of radioactivity from ³H-NAD into TCA-precipitated proteins in the absence or presence of 30 μM PHE. (c) PARG-dependent reduction of radioactivity incorporation is concentration dependent. Each point/column represents the mean±s.e.mean of three (a, b) and two (c) experiments conducted in duplicate.