Inhibition of human neuroblastoma DNA polymerase activities by plant lectins and toxins.
The effects of concanavalin A and ricin (RCAII, Mr 65,000) on [3H]thymidine incorporation into human neuroblastoma IMR-32 DNA showed reduction of total DNA synthesis to 50% and 70% of control, respectively. Two DNA polymerase (DNA nucleotidyltransferase, EC 2.7.7.7.) activities (alpha and beta) involved in the biosynthesis in vitro of DNA were separated by sucrose density gradient centrifugation from IMR-32 cell homogenate. The DNA polymerase alpha activity was also purified by selective precipitation with polyethylene glycol (Mr 6000) followed by agarose-concanavalin A column chromatography. The activities of both DNA polymerases were examined at various concentrations of mutagenic and nonmutagenic plant agglutinins and the toxin ricin. Concanavalin A and ricin specifically inhibited DNA polymerase alpha activity (activity reduced to 19% and 10%, respectively), whereas DNA polymerase beta activity was inhibited (reduced to 16%) by red kidney bean agglutinin (PHA-P).
D002460:Cell Line; D002474:Cell-Free System; D003208:Concanavalin A / Q000494:pharmacology*; D004273:DNA, Neoplasm / Q000096:biosynthesis; D037102:Lectins / Q000494:pharmacology*; D009374:Neoplasms, Experimental / Q000201:enzymology; D009447:Neuroblastoma / Q000201:enzymology*; D019384:Nucleic Acid Synthesis Inhibitors; D012276:Ricin / Q000494:pharmacology*
D004273:DNA, Neoplasm; D037102:Lectins; D019384:Nucleic Acid Synthesis Inhibitors; D003208:Concanavalin A; D012276:Ricin