In Vitro DNA Deamination by α-Nitrosaminoaldehydes Determined by GC/MS-SIM Quantitation

• Published in: Chemical research in toxicology 2000-02, Vol.13 (2), p.72-81
• Main Authors: Park, Misun, Loeppky, Richard N
• Format: Article
• Language: English
• Subjects: Adenine - chemistry; Aldehydes - pharmacology; Animals; Cattle; Cytosine - chemistry; Deamination; Diethylnitrosamine - analogs & derivatives; Diethylnitrosamine - chemical synthesis; Diethylnitrosamine - pharmacology; DNA - chemistry; DNA - drug effects; Gas Chromatography-Mass Spectrometry; Guanine - chemistry; N-Nitrosodiethanolamine; Nitrosamines - chemical synthesis; Nitrosamines - pharmacology
• ISSN: 0893-228X; 1520-5010
• DOI: 10.1021/tx990126d

The deamination of DNA bases by three α-nitrosaminoaldehydes, butylethanalnitrosamine, methylethanalnitrosamine, and N-nitroso-2-hydroxymorpholine (NHMOR), the direct metabolite of potent animal carcinogen N-nitrosodiethanolamine, was demonstrated by a set of in vitro experiments. The deamination of guanine, adenine, and cytosine bases in nucleotides, oligonucleotides, and calf thymus DNA gave xanthine, hypoxanthine, and uracil, respectively. The order of relative reactivities of the bases was as listed above. Deamination of cytosine to uracil was detected by the reaction of 32P-labeled oligonucleotide ([5‘-32P]CGAT) followed by enzymatic hydrolysis. Quantitative analysis of deamination of guanine and adenine in calf thymus DNA was performed by a gas chromatography/mass spectrometry-selected ion monitoring method. Both the extent and the rate of the deamination reactions which occur by transnitrosation from the α-nitrosaminoaldehyde to the base were determined for formation of xanthine and hypoxanthine. The deamination of guanine by NHMOR remained significant at low substrate levels.