IRON COMPLEXES OF BLEOMYCIN AND TALLYSOMYCIN

Using uv-visible absorption, epr, electrochemistry, and 13C nmr, the Fe(II) and Fe(III) binding sites of the antitumor antibiotics bleomycin and tallysomycin have been located. Both drugs appear to utilize the amine-pyrimidine-imidazole region for iron binding. The ligating atoms of the drugs for Fe(II) and Fe(III) are dependent for iron and the presence of buffer ions. The ligation of the pyrimidine moiety has been determined under a variety of experimental conditions and correlated with epr observation of high and low spin forms of Fe(III). The results indicate that the displacement of some of the ligating atoms does not inhibit the action of the iron-drug complex. © 1979.