ABSTRACT
The enzyme catalyzes the successive transfer of the adenosine diphosphate (ADP)-ribose moiety of nicotinamide adenine-dinucleotide (NAD) to generate a covalently bound homopolymer of poly ADP-ribose on nuclear protein acceptors. The poly ADP-ribosylation reaction was first demonstrated in rat liver nuclei. The implication of poly (ADP-ribose) polymerase in deoxyribonucleic acid (DNA) replication arises from observations where its enzymatic activity was found to be higher in proliferating cells than in quiescent cells. Evidence indicating the involvement of poly ADP-ribosylation in DNA repair has been seen in observations where alkylating agents and other DNA-damaging treatments result in the depletion of intracellular NAD pools and the increase in poly (ADP-ribose) synthesis. Histone H1 and core histones are major acceptors of poly (ADP-ribose) among the class of nuclear proteins. A considerable amount of new information has emerged from a variety of groups aimed at the elucidation of the function and interaction with chromatin of the nonhistone protein, poly (ADP-ribose) polymerase.
