Effects of photo-activated bleomycin on deoxyribonuclease I, exonuclease III and deoxyribonucleic acid polymerase I reactions.
The activity of bleomycin to break the strand of deoxyribonucleic acid (DNA) in the presence of 2-hydroxy-1-ethanethiol (2-mercaptoethanol) was enhanced by ultraviolet (UV) irradiation. Photo-activated bleomycin stimulated the action of deoxyribonuclease I (DNase I) to degrade DNA and the DNA synthesis by DNA polymerase I with DNase I. On the other hand, although UV-irradiated bleomycin scarcely broke the DNA strand in the presence of 1,2-benzenediol (catechol), it stimulated the action of DNase I to degrade DNA in the presence of catechol. In accordance with the inhibition by catechol, when DNA treated with UV-irradiated bleomycin in the presence of catechol was employed as a primer for the DNA synthesis, the incorporation of precursor into the acid-insoluble fraction by DNA polymerase I with exonuclease III was reduced to about one-half of the incorporation into DNA treated with unirradiated bleomycin. These findings suggest that the ability of bleomycin to bind to double-helical DNA forming regions sensitive to DNase I was increased by an appropriate dose of UV irradiation and that catechol inhibited the activity of the UV-irradiated bleomycin to break the DNA strand rather than to bind to DNA.
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D001761:Bleomycin / Q000138:chemical synthesis / Q000494:pharmacology* / Q000528:radiation effects; D004256:DNA Polymerase I / Q000037:antagonists & inhibitors*; D003851:Deoxyribonucleases / Q000037:antagonists & inhibitors*; D004926:Escherichia coli / Q000201:enzymology; D005090:Exodeoxyribonucleases / Q000037:antagonists & inhibitors*; D010777:Photochemistry; D014466:Ultraviolet Rays
D001761:Bleomycin; D004256:DNA Polymerase I; D003851:Deoxyribonucleases; D005090:Exodeoxyribonucleases; C020133:exodeoxyribonuclease III