Method for the Rapid Detection and Molecular Characterization of DNA Alkylating Agents by MALDI-TOF Mass Spectrometry
作者:Ignazio Garaguso、Roman Halter、Jacek Krzeminski、Shantu Amin、Jürgen Borlak
DOI:10.1021/ac101568h
日期:2010.10.15
Metabolic activation of polycyclic aromatic hydrocarbons (PAH) may cause DNA adduct formation. While these are commonly detected by the 32P-postlabeling assay, this method is not informative on the chemical nature of the alkylating agent. Here we report a simple and reliable method that employs MALDI-TOF-MS with 2,5-dihydroxybenzoic acid (DHB) matrix layer (ML) sample preparations for the detection and structural characterization of PAH-DNA adducts. The method involves the enzymatic digestion of DNA to 2′-deoxynucleotides followed by solid phase extraction to remove salt and other contaminants prior to MALDI-MS analysis. By collision induced dissociation (CID) structurally relevant fragments are obtained to permit characterization of the alkylating molecules and the adducted nucleotide. Next to guanosine, adenosine and cytidine adducts formed from reactions with (±)-anti-benzo[a]pyrene-7,8-diol-9,10-epoxide (B[a]PDE) are identified at a sensitivity of <100 fmol and a mass accuracy of <10 ppm. Studies with (±)-anti-benzo[c]chrysene-9,10-diol-11,12-epoxide (B[c]ChDE) further document the versatility and usefulness of the method. When compared with the 32P-postlabeling assay MALDI-MS only indentified deoxycytidine as well nucleoside and dinucleotides adducts. Therefore, this sensitive method enables molecular specification and characterization of adducted nucleotides and of the alkylating agent, and thus, provides comprehensive information that is beyond the 32P-postlabeling assay.
多环芳烃(PAH)的代谢活化可能会导致DNA加合物形成。虽然这些通常可以通过32P后标记检测法检测到,但这种方法并不能提供烷基化剂的化学性质信息。在此,我们报告了一种简单可靠的方法,该方法利用MALDI-TOF-MS与2,5-二羟基苯甲酸(DHB)基质层(ML)样品制备,用于检测和结构表征PAH-DNA加合物。该方法包括将DNA酶解为2′-脱氧核苷酸,然后进行固相萃取以去除盐和其他污染物,再进行MALDI-MS分析。通过碰撞诱导解离(CID),获得结构相关的片段,从而表征烷基化分子和加合的核苷酸。与鸟苷类似,与(±)-反式苯并[a]芘-7,8-二醇-9,10-环氧化物(B[a]PDE)反应形成的腺苷和胞苷加合物,其识别灵敏度小于100 fmol,质量精度小于10 ppm。与(±)-反式苯并[c]屈-9,10-二醇-11,12-环氧化物(B[c]ChDE)的研究进一步证明了该方法的多功能性和实用性。与32P