Properties of aflatoxin-DNA adducts formed by photoactivation and characterization of the major photoadduct as aflatoxin-N7-guanine.
Aflatoxin-DNA adducts were formed by microsomal and photoactivation, using nick-translated DNA labelled with 14C in each of the DNA bases [3H]AFB1 and [3H]AFB2. DNA adducts were analysed by HPLC of DNA hydrolysates, and were characterized as double labelled peaks with specific retention times. The only AF-DNA adducts which were detected in significant amounts were guanine adducts, irrespective of the type of aflatoxin used or the mode of its activation. No stable adduct with adenine, cytosine or thymine was detected. UV spectra, proton NMR spectroscopy and mass spectrometry are consistent with the notion that the major AFB1-DNA photoadduct is the N7-guanine adduct. This report provides direct evidence for the existence of aflatoxin photoadducts formed on DNA.
Shaulsky
G
G
Department of Biochemistry, Tel-Aviv University, Israel.
Johnson
R L
RL
Shockcor
J P
JP
Taylor
L C
LC
Stark
A A
AA
D016604:Aflatoxin B1 / Q000031:analogs & derivatives; D000348:Aflatoxins / Q000378:metabolism*; D000818:Animals; D001711:Biotransformation; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000378:metabolism*; D006147:Guanine / Q000031:analogs & derivatives* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D013058:Mass Spectrometry; D008861:Microsomes / Q000378:metabolism; D010777:Photochemistry; D051381:Rats; D011919:Rats, Inbred Strains; D013056:Spectrophotometry, Ultraviolet; D014466:Ultraviolet Rays
D000348:Aflatoxins; D006147:Guanine; C028319:2,3-dihydro-2-(N(7)-guanyl)-3-hydroxyaflatoxin B1; C029753:aflatoxin B2; D004247:DNA; D016604:Aflatoxin B1