Bleomycin-DNA Interactions: Fluorescence and Proton Magnetic Resonance Studies

Mingjien Chien, Arthur P. Grollman, Susan B. Horwitz

Research output: Contribution to journalArticlepeer-review

231 Scopus citations


The interaction of bleomycin A2 with DNA has been examined by fluorescence spectroscopy and proton magnetic resonance techniques. Fluorescence bands observed at 353 and 405 nm in the spectrum of bleomycin were assigned to the bithiazole and 4-aminopyrimidine rings, respectively. Quenching of bithiazole fluorescence by DNA was used to determine apparent equilibrium constants for the complex which, in 2.5 mM tris(hydroxymethyl)aminomethane buffer, pH 8.4, are 1.2 × 105 M-1 for bleomycin and 1.4 × 105 M-1 for tripeptide S, a partial acid hydrolysis product of the antibiotic. Under these conditions, one molecule of bleomycin binds for every five to six base pairs in DNA. In the proton magnetic resonance spectrum of bleomycin, resonances emanating from the bithiazole rings and dimethylsulfonium groups are preferentially broadened and reduced in intensity in the presence of DNA, suggesting that these moieties bind most tightly to the polymer.

Original languageEnglish (US)
Pages (from-to)3641-3647
Number of pages7
Issue number16
StatePublished - Aug 1 1977
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry


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