Involvement of singlet oxygen in photoactivation of aflatoxins B1 and B2 to DNA-binding forms in vitro.
UVA-activated aflatoxin B1 (AFB1) and AFB2 bound covalently to DNA. The rate of binding increased in D2O versus H2O and decreased by diazabicyclo-octane, azide, aniline, 2-naphthylamine and by efficient stripping of oxygen. Similarly to DNA-binding, singlet oxygen (1O2) formation increased in D2O and was inhibited by singlet scavengers, as judged by the formation of malonaldehyde from linolenic acid. The above argue for the involvement of 1O2 in aflatoxin photoactivation to DNA-binding species. A model for the mechanism is proposed.
Stark
A A
AA
Department of Biochemistry, Tel-Aviv University, Israel.
Gal
Y
Y
Shaulsky
G
G
D015081:2-Naphthylamine / Q000494:pharmacology; D016604:Aflatoxin B1; D000348:Aflatoxins / Q000378:metabolism*; D001386:Azides / Q000494:pharmacology; D002273:Carcinogens / Q000378:metabolism*; D004247:DNA / Q000378:metabolism*; D007700:Kinetics; D008027:Light; D008042:Linolenic Acids / Q000378:metabolism; D008315:Malondialdehyde / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D010777:Photochemistry; D010879:Piperazines / Q000494:pharmacology; D011837:Radiation-Protective Agents / Q000494:pharmacology; D026082:Singlet Oxygen; D014466:Ultraviolet Rays
D000348:Aflatoxins; D001386:Azides; D002273:Carcinogens; D008042:Linolenic Acids; D010879:Piperazines; D011837:Radiation-Protective Agents; D026082:Singlet Oxygen; D008315:Malondialdehyde; C029753:aflatoxin B2; D004247:DNA; D016604:Aflatoxin B1; D015081:2-Naphthylamine; D010100:Oxygen; C007306:triethylenediamine