Poly(ADP-ribose)synthetase from HeLa cell nuclei: purification and properties

Poly(ADP-ribose)synthetase has been purified over 600-fold from HeLa cell nuclei. Upon electrophoresis on 9% polyacrylamide slab-gel in the presence of SDS, the purified enzyme resolved in two bands that showed similar apparent Mr values, 110,000 and 118,000. The aminoacid composition of the two components differed from compositions reported for the same enzyme from other sources. In accordance with other reports, the enzyme purified from HeLa cell nuclei exhibited an absolute dependence on DNA and its activity was modulated by changes in the histone concentration. Incubation of intact nuclei from HeLa cells with [14C]NAD resulted in the isolation of a poly(ADP-ribose)synthetase to which a definite radioactivity is bound. These results are taken as a further demonstration that the enzyme can be auto-ADP-ribosylated.