Bleomycin biological properties

The overall strategy is shown in Figure 2. In the first step, nonradio-active cobalt (II) is bound to bleomycin A2 and air-oxidized to form the stable cobalt (III)-bleomycin A2 complex. The dimethyl(y-aminopropyl)-sulfonium group at the right side of the structure is unique to bleomycin A2 the other bleomycins have quite different terminal amine residues. Since the biological transport properties of all of the bleomycins are similar (17), the structure of the terminal amine residue appears to have relatively little influence on transport into cancer cells therefore this residue is a promising site for chemical modification. 

---