The effect of bleomycin on prolyl hydroxylase and DNA chain breakage: structure-activity relationship

The activity of purified prolyl hydroxylase (proline, 2-oxoglutarate dioxygenase, EC 1.14.11.2) was enhanced about 3-fold by addition of bleomycin in the assay mixture. Various members of the bleomycin family, their derivatives and degradation products were investigated for activities against prolyl hydroxylase together with their activities of DNA chain breakage to determine relationships between the structure of bleomycin and its various actions. All the bleomycins with various terminal amine parts and desamide bleomycin stimulated the enzymatic activity but did not exhibit an effect on DNA chain breakage. The stimulatory activity of bleomycin was not decreased by hydrolysis with 0.3 N H2SO4 at 80 degrees C for 6 hours, conditions which liberates the sugar moiety, but was eliminated by hydrolysis with 6 N HCl at 105 degrees C for 24 hours. In contrast both treatments decreased the DNA chain breakage activity of bleomycin. Optical spectral studies revealed that all the bleomycins and their hydrolysates which stimulated the prolyl hydroxylase activity made complexes with ferrous ion, one of the cofactors of this enyzme.