Formation of methyl ester of 2-methylglyceric acid from thymine glycol residues: a convenient new method for determining radiation damage to DNA.
Thymine glycol residues in DNA or thymidine were converted to methyl 2-methylglycerate by reaction with alkaline borohydride followed by methanolic HCl. The product was labeled either from [3H]DNA or from [3H]borohydride and was followed by cochromatography with authentic 14C-labeled material. Following acid hydrolysis, the identity of 2-methylglyceric acid was confirmed by high-resolution mass spectrometry, NMR, IR, and elemental analysis. Treatment of DNA or thymidine with X-irradiation, with H2O2 and Fe2+, with H2O2, Cu2+, and ascorbate, and with H2O2 and ultraviolet light, permanganate, or sonication all produced methyl 2-methylglycerate in varying amounts after alkaline borohydride and methanolic HCl, whereas untreated DNA did not. The data indicate that certain oxidants including hydroxyl radicals generated by chemical means or from radiolysis of water convert thymine residues to thymine glycols in DNA, which can be determined as methyl 2-methylglycerate.
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D000818:Animals; D001894:Borohydrides; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D004247:DNA / Q000302:isolation & purification / Q000528:radiation effects*; D005260:Female; D005988:Glyceric Acids; D009682:Magnetic Resonance Spectroscopy; D010053:Ovary; D013941:Thymine / Q000031:analogs & derivatives*; D014316:Tritium; D014965:X-Rays
D001894:Borohydrides; D005988:Glyceric Acids; D014316:Tritium; C049222:methyl 2-methylglycerate; C029389:thymine glycol; D004247:DNA; D013941:Thymine