title: n-Propyldiazonium ion alkylates O6 of guanine with rearrangement, but alkylates N-7 without rearrangement.
abstract: Treatment of guanosine with n-propylnitrosourea yields 7-n-propylguanine (after acid hydrolysis) but O6-isopropylguanosine. Similarly, injection of [3H]di-n-propylnitrosamine into Sprague--Dawley rats resulted in isolation of 7-n-propylguanine from RNA, but O6-isopropylguanosine. The amounts of the different adducts indicate that attack at both N-7 and O6 of guanine proceed by bimolecular substitution (otherwise significant levels of 7-isopropylguanine should have been seen), but the observed rearrangement indicates that the transition state for reaction at O6 may be much looser than that for reaction at N-7.
mesh_terms: D000478:Alkylation; D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D002855:Chromatography, Thin Layer; D006147:Guanine / Q000031:analogs & derivatives* / Q000302:isolation & purification / Q000378:metabolism; D006151:Guanosine / Q000031:analogs & derivatives* / Q000302:isolation & purification / Q000378:metabolism*; D008099:Liver / Q000378:metabolism; D008297:Male; D009602:Nitrosamines / Q000494:pharmacology*; D009607:Nitrosourea Compounds / Q000378:metabolism; D012313:RNA / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D009602:Nitrosamines; D009607:Nitrosourea Compounds; D006151:Guanosine; C013161:N-nitroso(di-n-propyl)amine; C024069:7-n-propylguanine; D006147:Guanine; D012313:RNA; C020796:propylnitrosourea; C035325:O-isopropylguanosine