title: Two proteolytic degradation products of calf-thymus poly(ADP-ribose) polymerase are efficient ADP-ribose acceptors. Implications for polymerase architecture and the automodification of the polymerase.
abstract: Two polypeptides with molecular masses of 76 and 59 kDa were found to copurify with poly(ADP-ribose) polymerase from calf thymus, and to be as efficient acceptors of ADP-ribose as the polymerase itself. Analysis of their CNBr fragments by sodium dodecylsulfate/polyacrylamide gel electrophoresis revealed that the polypeptides were derived from the 112-kDa polymerase. Isolation of poly(ADP-ribose) polymerase in the absence of protease inhibitors resulted in a loss of more than 90% of the polymerase activity and an increased proportion of the 76-kDa and 59-kDa polypeptides in the final polymerase preparation. When the polymerase and the two polypeptides were separated by gel filtration or polyacrylamide gel electrophoresis in 5% acetic acid, no polymerase activity was found associated with the two fragments. Analysis of the CNBr fragments of the three polypeptides after incubation of the enzyme preparation with [32P]NAD showed that most of the fragments were radioactive, indicating multiple ADP-ribosylation sites. Several ADP-ribosylated fragments were found to be common to all three polypeptides, or to two of them.
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D002384:Catalysis; D002417:Cattle; D055598:Chemical Phenomena; D002621:Chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D009244:NAD+ Nucleosidase / Q000302:isolation & purification*; D009702:Nucleoside Diphosphate Sugars / Q000378:metabolism*; D010446:Peptide Fragments / Q000302:isolation & purification* / Q000378:metabolism; D011065:Poly(ADP-ribose) Polymerases / Q000302:isolation & purification*; D013950:Thymus Gland / Q000201:enzymology*
chemical_list: D009702:Nucleoside Diphosphate Sugars; D010446:Peptide Fragments; D000246:Adenosine Diphosphate Ribose; D011065:Poly(ADP-ribose) Polymerases; D009244:NAD+ Nucleosidase