Poly(ADP-Ribose) Polymerase: Determination of Content from TCA-Precipitated Cells, Existence of Species-Specific Isoforms and Changes During the Growth Cycle

Abstract

Poly(ADP-ribose) polymerase itself is one of the major acceptors of poly(ADP-ribose) residues under conditions of DNA fragmentation in vitro (1) and in vivo (2, 3). For a better understanding of the involvement of polymerase in alterations of chromatin structure and function it is important to know the absolute content of the enzyme under varying conditions. Because of the multiple factors influencing polymerase activity, determination of the content via activity is not reliable. We have developed a procedure for immunoquantitation of poly(ADP-ribose) polymerase from TCA precipitates. In this way artifactual degradation can be avoided. When applied in conjunction with Western blotting, the procedure also allows the analysis of isoforms of the enzyme present in vivo“ and reactivation experiments on SDS gels from the same sample.