Reaction of Br3'2- with 2-Deoxy-D-ribose. A Preferred Attack at C-l*

Pulse Radiolysis, y-Radiolysis, 2-Deoxy-D-ribose, G-values, Radical Reactions In the photolysis of 5-bromouracil containing DNA Br atoms are expected inter mediates. In order to evaluate the possible site of attack of the Br atom at the sugar moiety of DNA the reaction of 2-deoxy-D-ribose with the Br atom (complexed with two bromide ions) was investigated. Hydroxyl radicals generated by the radiolysis of N20 saturated aqueous solutions were converted into Br3-2_ radicals by 1 M bromide ions. Br3-2reacts with 2-deoxy-D-ribose (k = 3.7 • 104M -1s -1, pulse radiolysis). The major product is 2-deoxy-D-erythro-pentonic acid (G = 2.4, y-radiolysis). It is formed by hydrogen abstraction from C-l and oxidation of this radical by other radicals. An alternative route via the radical at C-2 is neglible. It follows that Br3-2~ reacts preferentially at C-l of 2-deoxy-£>-ribose.