Are all nucleotidyl transferases metalloenzymes?

Pablo Valenzuela, Robert W. Morris, Anthony Faras, Warren Levinson, William J. Rutter

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62 Citations (Scopus)


Previous studies (1,2) have shown that DNA polymerases (sea urchin and E. coli I) and E. coli RNA polymerases are zinc metalloproteins. We report here that DNA-dependent RNA polymerases I and II from rat liver, I, II and III from sea urchin, and RNA-dependent DNA polymerase (reverse transcriptase) from Rous sarcoma virus are inhibited by pre-incubation with the chelating agent, o-phenanthroline. These enzymes are not affected by pre-incubation with the related compound, m-phenanthroline, which is not a metal chelating agent. The data suggest that, in addition to Mg++ or Mn++, the enzymes require a tightly bound metal ion (possibly zinc) for catalytic activity. The DNA-terminal transferase is also inhibited by o-phenanthroline but not m-phenanthroline (3). On the other hand, we found that tRNA-nucleotidyl transferases from Rous sarcoma virions and yeast are not affected by either o- or m-phenanthroline. These observations suggest that many but not all nucleotidyl transferases are metallo-enzymes.

Original languageEnglish
Pages (from-to)1036-1041
Number of pages6
JournalBiochemical and Biophysical Research Communications
Issue number3
Publication statusPublished - 6 Aug 1973

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology


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