Quantitation of four guanine oxidation products from reaction of DNA with varying doses of peroxynitrite.
The oxidation products obtained from the reaction of peroxynitrite (ONOO-) with dG include-among others-8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), 2,2-diamino-4[(2-deoxy-beta-d-erythro-pentafuranosyl)amino]-5(2H)-oxazolone (oxazolone), spiroiminodihydantoin, and N1-(beta-d-erythro-pentofuranosyl)-5-guanidinohydantoin (guanidinohydantoin). In the present work, the formation of these products from the treatment of calf thymus DNA with varying amounts of ONOO- was studied quantitatively in vitro. 13C-, 15N-labeled standards were synthesized for the nucleosides of interest, and calf thymus DNA was reacted with ONOO- and digested enzymatically down to the nucleoside level. Specific modifications in the DNA were measured by HPLC separation followed by electrospray ionization tandem mass spectrometric analysis in the selected reaction-monitoring mode. Artifacts of the above four oxidation products, arising from oxidation of dG and/or 8-oxodG during DNA digestion and subsequent workup, were evaluated with 7-15N-dG and/or stable-isotope-labeled 8-oxodG as internal standards. Levels of artifactual 8-oxodG were about 5/10(6) nucleosides. The artifacts of spiroiminodihydantoin and guanidinohydantoin, arising from 8-oxodG, were 3.7% and 0.6% of the measured 8-oxodG values, respectively. No artifacts of oxazolone were detected. 8-OxodG and oxazolone were formed dose-dependently in DNA treated with ONOO-, while the levels of spiroiminodihydantoin and guanidinohydantoin increased significantly at low ONOO- doses, and then dropped off at higher ONOO- doses. The complexity of these dose-response relationships is likely due to the dual role of peroxynitrite as both an oxidant and a nucleophile in competition with water.
Yu
Hongbin
H
Biological Engineering Division, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Room 56-731A, Cambridge, Massachusetts 02139, USA.
Venkatarangan
Lata
L
Wishnok
John S
JS
Tannenbaum
Steven R
SR
D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D006146:Guanidines / Q000737:chemistry / Q000378:metabolism; D006147:Guanine / Q000737:chemistry* / Q000378:metabolism*; D006151:Guanosine / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D006827:Hydantoins / Q000737:chemistry / Q000378:metabolism; D015394:Molecular Structure; D010081:Oxazolone / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D030421:Peroxynitrous Acid / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D013141:Spiro Compounds / Q000737:chemistry / Q000378:metabolism
D006146:Guanidines; D006827:Hydantoins; D013141:Spiro Compounds; C467338:guanidinohydantoin; C408822:spiroiminodihydantoin; D006151:Guanosine; D030421:Peroxynitrous Acid; D010081:Oxazolone; D006147:Guanine; D004247:DNA