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Electrospray mass spectrometry (ES-MS) is a powerful tool for analysis of carcinogen-adducted DNA. In this study, we developed a quantitative isotope dilution method for analysis of N-(deoxyguanosine-8-yl)-4-aminobiphenyl (dG-C8-4-ABP), the principal nucleoside adduct derived from enzymatic hydrolysis of 4-aminobiphenyl (4-ABP)-modified DNA. The method used column switching valves to perform on-line sample concentration and cleanup, which permitted direct analysis of enzymatic DNA hydrolysates using narrow-bore liquid chromatography (LC). ES-MS detection was performed using a single quadrupole instrument by monitoring M+H+ and two fragment ions characteristic for dG-C8-4-ABP, along with M+H+ and a fragment ion for the deuterated internal standard. The detection limit for dG-C8-4-ABP in DNA hydrolysates was ~10 pg on-column, equivalent to 0.7 dG-C8-4-ABP adducts in 107 normal nucleotides for a sample containing 100 μg DNA. The method was applied to the analysis of calf thymus DNA modified in vitro through reaction with N-hydroxy-4-ABP and of hepatic DNA isolated from mice treated in vivo with two dose levels of 4-ABP.
Keywords: 4-ABP, 4-aminobiphenyl; ACN, acetonitrile; DELFIA, dissociation-enhanced lanthanide fluoroimmunoassay; dG, 2′-deoxyguanosine; dG-C8-4-ABP, N-(deoxyguanosine-8-yl)-4-aminobiphenyl; ELISA, enzyme-linked immunosorbent assay; ES, electrospray; ethenoGua, N-2,3-ethenoguanine; Gua, guanine; IAC, immunoaffinity chromatography; M1G, 3-(2-deoxy-β-d-erythro-pentofuranosyl)-pyrimido[1,2-α]purin-10(3H)-one; MS, mass spectrometry; NICI, negative ion chemical ionization; RIA, radioimmunoassay; SIR, selected ion recording.
Journal Article. 4323 words. Illustrated.
Subjects: Clinical Cytogenetics and Molecular Genetics
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