Reactions of Sugar-Derived Radicals in Nucleosides and Nucleotides

Reactions of Sugar-Derived Radicals in Nucleosides and Nucleotides 

The bond dissociation energies of the various C-H bonds in the 2-deoxyribose moiety have been calculated on the basis of N(1)-II BDE in dGuo (380 kj mol-1 Steenken et al. 2001). They are compiled in Chap. 4, Table 4.6. 

The C(l )-H is the most loosely bound hydrogen, followed by C(4 )-H. In H-abstraction reactions, these positions are the most likely ones to be attacked be reactive free radicals, while those bound to C(2 ) are the most unlikely ones. This argument only holds when other parameters, e.g. steric factors and aces-sibility as in DNA (Chap. 12.2), can be neglected. In the ribo-series, the C(2 )-H is, of course, again only loosely bound, and many striking differences between the free-radical chemistry of 2 -deoxynuleosides and nucleosides and more noticeably in the corresponding homopolymers may be due to this difference (Chap. 11.2). 

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