title: All oxygens in nucleic acids react with carcinogenic ethylating agents.
abstract: Over 80% of ethylnitrosourea and ethylnitrosoguanidine modification of nucleic acids is on oxygens. The reactivity of oxygens (other than ribose and phosphate) in single-stranded RNA is: O2 of C greater than O2 of U greater than O6 of G greater than O4 of U. In double-stranded DNA the order is: O2 of T equals O6 of G greater than O4 of T greater than O2 of C. Oxygen reactivity of single-stranded DNA resembles RNA. The glycosidic bond of O2-alkylpyrimidines is labilised.
mesh_terms: D000478:Alkylation; D002273:Carcinogens; D003562:Cytidine / Q000031:analogs & derivatives / Q000032:analysis; D004247:DNA; D005038:Ethylnitrosourea; D009154:Mutation; D009604:Nitrosoguanidines; D009607:Nitrosourea Compounds; D009696:Nucleic Acids; D010100:Oxygen; D012313:RNA; D013329:Structure-Activity Relationship; D013936:Thymidine / Q000031:analogs & derivatives / Q000032:analysis; D014529:Uridine / Q000031:analogs & derivatives / Q000032:analysis
chemical_list: D002273:Carcinogens; D009604:Nitrosoguanidines; D009607:Nitrosourea Compounds; D009696:Nucleic Acids; D003562:Cytidine; D012313:RNA; D004247:DNA; D005038:Ethylnitrosourea; D010100:Oxygen; D013936:Thymidine; D014529:Uridine