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Quantitative Measurements of Carcinogen-DNA Adduct Using MALDI Time-Of-Flight Mass Spectrometry

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Zhuoli Huang (Creator)
Institution
The University of North Carolina at Greensboro (UNCG )
Web Site: http://library.uncg.edu/
Advisor
Norman Chiu

Abstract: Many carcinogens and their electrophilic metabolites react readily with DNA, and form different types of DNA adducts. Clinically, DNA adducts have been linked to cancer diseases. Also, different DNA adducts have been used as biomarkers to monitor the exposure of individuals to specific carcinogens. In this study, we have explored the use of high throughput matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) technique to quantitate carcinogen-DNA adducts. A pure synthetic aromatic amine-DNA adduct, namely N-(2’-deoxyguanosin-8yl)-4-aminobiphenyl (dG-ABP) that has been clinically associated with bladder cancer, was selected as a representing carcinogen-DNA adduct in this study. Among the four natural nucleobases, guanine is the most frequent site for DNA adduction. Another reason for choosing a dG adduct is due to the N-glycosidic bond between guanine and ribose is the weakest when comparing to the other deoxyribonucleotides. This intrinsic property of dG adducts has led to the dissociation of their corresponding aglycon ions when mass spectroscopic techniques were used to perform their qualitative measurements, including MALDI-TOF MS. In our initial study, a novel approach of using G-ABP aglycon ion instead of the dG-ABP ion to perform the quantitation of dG-ABP has been examined. In an alternative approach to perform the dG-ABP quantitation, the effects of different MALDI matrices, sample preparation methods, and various instrumental parameters were studied. Using the optimal conditions and dG-ABP ion, a calibration graph for the quantitation of dG-ABP was constructed with using 2’-deoxyguanisine monohydrate as internal standard. The linearity of the calibration graph had a R-squared value of 0.9897. The limit of quantitation for dG-ABP was at 2.23µM with a signal-to-noise ratio of 32.2, and the linear dynamic range for quantitation was extended to 1,000µM. The results of this study have demonstrated for the first time MALDI-TOF MS is a viable technique for carrying out quantitative measurements of carcinogen-DNA adducts.

Additional Information

Publication
Thesis
Language: English
Date: 2008
Keywords
Carcinogen, DNA adducts, Measurements
Subjects
Carcinogens $x Research.
DNA $x Research.
Carcinogens $x Measurement.
DNA $x Measurement.
Matrix-assisted laser desorption-ionization.
Bladder $x Cancer $x Research.
Mass spectrometry.