title: Stimulation of nuclear poly (adenosine diphosphate-ribose) polymerase activity from HeLa cells by endonucleases.
abstract: Isolated nuclei from HeLa cells can incorporate labeled ADP-ribose from NAD into an acid-precipitable product, poly(ADP-ribose). This reaction is stimulated by 4-6-fold by the addition of deoxyribonuclease I to the complete reaction mixture. If the nuclei are treated first with deoxyribonuclease I, no effect is seen; the stimulation is only apparent when the two enzymes deoxyribonuclease I and poly(ADP-ribose) polymerase, are operating at the same time. After making several minor modifications in the assay mixture, it was found that another endonuclease, micrococcal nuclease, can also stimulate the poly(ADP-ribose) polymerase activity of HeLa nuclei. A comparison of the two stimulatory effects indicated that the two endonucleases activated to the poly(ADP-ribose) polymerase activity of HeLa nuclei in the same way. Overall this evidence suggests that poly(ADP-ribose) polymerase may have a functional role in the process of DNA repair.
mesh_terms: D002467:Cell Nucleus / Q000378:metabolism; D004260:DNA Repair; D003851:Deoxyribonucleases / Q000494:pharmacology; D004720:Endonucleases / Q000494:pharmacology*; D006367:HeLa Cells / Q000378:metabolism; D008836:Micrococcal Nuclease / Q000494:pharmacology; D009699:N-Glycosyl Hydrolases / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D009244:NAD+ Nucleosidase / Q000378:metabolism*; D009536:Niacinamide / Q000494:pharmacology; D009702:Nucleoside Diphosphate Sugars / Q000378:metabolism*; D010727:Phosphoric Diester Hydrolases / Q000494:pharmacology; D011064:Poly Adenosine Diphosphate Ribose / Q000378:metabolism*; D011402:Pronase / Q000494:pharmacology; D012260:Ribonucleases / Q000494:pharmacology; D012910:Snake Venoms; D013936:Thymidine / Q000494:pharmacology; D014316:Tritium
chemical_list: D009702:Nucleoside Diphosphate Sugars; D012910:Snake Venoms; D009243:NAD; D014316:Tritium; D009536:Niacinamide; D011064:Poly Adenosine Diphosphate Ribose; D003851:Deoxyribonucleases; D004720:Endonucleases; D012260:Ribonucleases; D008836:Micrococcal Nuclease; D010727:Phosphoric Diester Hydrolases; D009699:N-Glycosyl Hydrolases; D009244:NAD+ Nucleosidase; D011402:Pronase; D013936:Thymidine