title: Reactivity and selectivity in light-induced free radical reactions of 2-propanol with purine and pyrimidine mononucleotides and dinucleoside monophosphates.
abstract: Photoalkylation reactions with 2-propanol, initiated with di-tert-butyl peroxide, of a variety of purine and pyrimidine mononucleotides and dinucleoside monophosphates lead to the substitution of an alpha-hydroxyisopropyl group for the H-8 atom of adenosine and the addition of the alcohol across the 5,6-double bond of the pyrimidines. Adenosine moieties blocked at their 3'-hydroxyl group are alkylated faster than those blocked at their 5'-hydroxyl. The reactivity of the uridine moieties of 3'-UMP, 5'-UMP, and uridylyl-(3',5')-uridine is not affected by the location of the phosphate group. However, the uridine moiety of uridylyl-(3',5')-adenosine is modified faster than that of adenylyl-(3',5')-uridine. It is suggested that steric hindrance imposed by the phosphate group determines the reactivity of adenosine moieties, while base stacking involving adenosine determines the reactivity of uridine moieties. These two effects play a major role in controlling the nature and degree of the selectivity of these photoalkylation reactions for either adenosine or uridine. Cytidine has been found to be inert in these reactions.
mesh_terms: D000433:1-Propanol; D000478:Alkylation; D001665:Binding Sites; D007700:Kinetics; D010777:Photochemistry; D011685:Purine Nucleotides; D011742:Pyrimidine Nucleotides
chemical_list: D011685:Purine Nucleotides; D011742:Pyrimidine Nucleotides; D000433:1-Propanol