Inhibition of human neuroblastoma DNA polymerase activities by plant lectins and toxins

Proc Natl Acad Sci U S A. 1979 May;76(5):2218-21. doi: 10.1073/pnas.76.5.2218.


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 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).

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Cell Line
  • Cell-Free System
  • Concanavalin A / pharmacology*
  • DNA, Neoplasm / biosynthesis
  • Lectins / pharmacology*
  • Neoplasms, Experimental / enzymology
  • Neuroblastoma / enzymology*
  • Nucleic Acid Synthesis Inhibitors*
  • Ricin / pharmacology*


  • DNA, Neoplasm
  • Lectins
  • Nucleic Acid Synthesis Inhibitors
  • Concanavalin A
  • Ricin