Structural differentiation of diastereomeric benzo[ghi]fluoranthene adducts of deoxyadenosine by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and postsource decay.
The product ion formation characteristics of four diastereomeric deoxyadenosine adducts formed by the reaction of the syn and anti diastereomers of trans-3,4-dihydroxy-5,5a-epoxy-3,4,5,5a-tetrahydrobenzo[ghi]fluoranthene are studied by matrix-assisted laser desorption ionization and postsource decay (PSD) to determine fragmentation pathways that may permit differentiation of their structures. The two adducts derived from each diol-epoxide with DNA differ in structure based on the cis/trans arrangement of the 3'-hydroxyl group on the benzo[ghi]fluoranthene (B[ghi]F) and the adenine base bound to the B[ghi]F 5a carbon. The two adduct diastereomers with the cis adenine-3'-hydroxyl configuration produce product ions at m/z 394 and m/z 510 formed by the loss of water that are not observed in the PSD spectra of the two trans isomers. The data suggest a mechanism of water loss that is initiated by a hydrogen-bonding interaction between the charge-bearing proton on the N1 atom and the 3'-hydroxyl oxygen on the polycyclic aromatic hydrocarbon (PAH). Fragmentation is initiated by the transfer of the adenine N1 proton from the nitrogen to the PAH 3'-hydroxyl oxygen and inductive cleavage of the C3-O(3) bond to form a benzylic carbocation on B[ghi]F. The proposed mechanism is supported by semiempirical molecular modeling calculations.
Chiarelli
M Paul
MP
Department of Chemistry, Loyola University Chicago, Chicago, Illinois 60626, USA.
Chang
Hui-Fang
HF
Olsen
Kenneth W
KW
Barbacci
Damon
D
Huffer
Duane M
DM
Cho
Bongsup P
BP
D000225:Adenine / Q000737:chemistry; D018736:DNA Adducts / Q000737:chemistry; D003839:Deoxyadenosines / Q000737:chemistry*; D005449:Fluorenes / Q000737:chemistry*; D006358:Hot Temperature; D006860:Hydrogen Bonding; D007477:Ions / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D009584:Nitrogen / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013237:Stereoisomerism; D014867:Water / Q000737:chemistry
D018736:DNA Adducts; D003839:Deoxyadenosines; D005449:Fluorenes; D007477:Ions; D014867:Water; C041510:benzo(ghi)fluoranthene; D000225:Adenine; D009584:Nitrogen; D010100:Oxygen