Isolation and characterization of a tRNA(guanine-7-)-methyltransferase from Salmonella typhimurium

Alfredo Colonna, Gennaro Ciliberto, Rita Santamaria, Filiberto Cimino, Francesco Salvatore

Research output: Contribution to journalArticlepeer-review


The tRNA modifying enzyme, S-adenosylmethionine:tRNA(guanine-7-)-methyltransferase, has been extensively purified from Salmonella typhimurium. A rapid and efficient purification method using phosphocellulose chromatography followed by ammonium sulfate precipitation and Sephadex G-100 gel filtration is described. The enzyme appears to be a single polypeptide chain with a molecular weight of approximately 25 000-30 000 daltons. The Km for S-adenosylmethionine and for undermethylated tRNA is 53 μ M and 3.4 μM, respectively. The methylation reaction is dependent on added monovalent or divalent cations; 5 mM spermidine, 3 mM MgCl2 and 1 mM spermine are the most effective. The enzyme, though not homogeneous, is free from contaminating ribonucleases and other tRNA methyltransferases.

Original languageEnglish
Pages (from-to)97-106
Number of pages10
JournalMolecular and Cellular Biochemistry
Issue number2
Publication statusPublished - Sep 1983

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics
  • Clinical Biochemistry
  • Cell Biology


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