Measurement of 8-Hydroxy-2'-Deoxyguanosine in DNA by High-Performance Liquid Chromatography-Mass Spectrometry: Comparison with Measurement by Gas Chromatography-Mass Spectrometry

Published

February 1, 2001

Author(s)

M. Dizdaroglu, Pawel Jaruga, H Rodriguez

Abstract

Measurement of 8-hydroxy-2'-deoxyguanosine (8-OH-dGuo) in DNA by high-performance liquid chromatography/mass spectrometry (HPLC/MS) was studied. A methodology was developed for separation by LC of 8-OH-dGuo from intact and modified nucleosides in DNA hydrolyzed by a combination of four enzymes: Dnase I, phosphodiesterases I and II, and alkaline phosphatase. The atmospheric pressure ionization-electrospray process was used for mass spectral measurements. A stable isotope-labeled analogue of 8-OH-dGuo was used as an internal standard for quantification by isotope-dilution MS (IDMS). Results showed that LC/IDMS with selected ion monitoring (SIM) is well suited for identification and quantification of 8-OH-dGuo in DNA at background levels and in damaged DNA. The sensitivity level of LC/IDMS-SIM was found to be comparable to that reported previously using LC-tandem MS (LC/MS/MS). It was found that approximately five lesions per 10⁶ DNA bases can be detected using amounts of DNA as low as 2 g. The results also suggest that this lesion may be quantified in DNA at levels of 1 lesion per 10⁶ DNA bases, or even lower, when more DNA is used. Up to 50 g of DNA per injection were used without adversely affecting the measurements. Gas chromatography/isotope-dilution MS with selected-ion monitoring (GC/IDMS-SIM) was also used to measure this compound in DNA following its removal from DNA by acidic hydrolysis or by hydrolysis with Escherichia coli Fpg protein. The background levels obtained by LC/IDMS-SIM and GC/IDMS-SIM were almost identical. Calf thymus DNA and DNA isolated from cultured HeLa cells were used for this purpose. This indicates that these two techniques can provide similar results in terms of the measurement of 8-OH-dGuo in DNA. In addition, DNA in buffered aqueous solution was damaged by ionizing radiation at different radiation doses and analyzed by LC/IDMS-SIM and GC/IDMS-SIM. Again, similar results were obtained by the two techniques. The sensitivity of GC/MS-SIM for 7,8- dihydro-8-oxoguanine was also examined and found to be much greater than that of LC/MS-SIM and the reported sensitivity of LC/MS/MS for 8-OH-dGuo. Taken together, the results unequivocally show that LC/IDMS-SIM is well suited for sensitive and accurate measurement of 8-OH-dGuo in DNA and that both LC/IDMS-SIM and GC/IDMS-SIM can provide similar results.

Citation

Nucleic Acids Research

Volume

29

Issue

No. 3

Pub Type

Journals

Keywords

8-Hydroxy-2'-deoxyguanosine, enzymatic hydrolysis, FPG protein, HeLa cells, high-performance liquid chromatography/m, oxidative DNA damage

Citation

Dizdaroglu, M. , Jaruga, P. and Rodriguez, H. (2001), Measurement of 8-Hydroxy-2'-Deoxyguanosine in DNA by High-Performance Liquid Chromatography-Mass Spectrometry: Comparison with Measurement by Gas Chromatography-Mass Spectrometry, Nucleic Acids Research (Accessed December 22, 2024)