On the chemistry of RNA degradation by Fe·bleomycin

Chris E. Holmes, Robert J. Duff, Gijs A. Van Der Marel, Jacques Van Boom, Sidney Hecht

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Abstract

The chemistry of RNA degradation by Fe·bleomycin was studied using two RNA substrates that are modified efficiently at a small number of sites by the antitumor antibiotic. Cleavage of a tRNA(His) precursor transcript by Fe(II)·BLM A2 was shown to require O2; cleavage was also observed when the same substrate was treated with Fe(III)·BLM A2 + H2O2. Consistent with earlier observations made for DNA, the extent of tRNA(His) precursor cleavage was greater for Fe(II)·BLM A5 than for Fe(II)·BLM A2; the least cleavage was obtained using Fe(II)·BLM demethyl A2. By the use of a 32P end labeled tRNA(His) precursor transcript that was also 3H labeled within the uracil moieties, it was shown that release of uracil was nearly stoichiometric with tRNA strand scission by Fe(II)·BLM A2. Nonetheless, treatment of the tRNA(His) with hydrazine following BLM-mediated cleavage indicated formation of a new product that- must have derived from a BLM-induced lesion. Also employed for characterization of BLM cleavage of RNA were the octanucleotides CGCTAGCG, C3-ribo-CGCTAGCG and C3-ara-CGCTAGCG. Analysis of the products of cleavage indicates that Fe BLM is capable of mediating cleavage by abstraction of a H atom either from C-4' H or C-1' H of the chimeric oligonucleotides.

Original languageEnglish (US)
Pages (from-to)1235-1248
Number of pages14
JournalBioorganic and Medicinal Chemistry
Volume5
Issue number6
DOIs
Publication statusPublished - Jun 1997
Externally publishedYes

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Organic Chemistry
  • Drug Discovery
  • Pharmaceutical Science

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