Reactions of the cation and anion radicals of several DNA bases

Abstract

Dertinger report the thymidine positive ion in powdered thymine crystals.27 The resolution is sufficient to resolve only the large methyl proton splitting of 19 G. This value is in good agreement with that found in our previous work8 considering the differences in molecular environment.

The Purine DNA Base Cation and Anion Radicals: An E.S.R. Study

“…The results of this present work and previous work in both alkaline (Holroyd and Glass 1968, Srinivasan et al 1969, Lion and van De Vorst 1970 and neutral (Sevilla, Van Paemel and Zorman 1972) glasses have shown that of the four DNA bases the thymine anion most readily protonates . We believe these results give the probable explanation for the fact that only the thymine anion has been found to protonate in y-irradiated DNA (Ormerod 1965) .…”

“…However, it is possible that the radicals they observe on warming are a result of attack by hydrogen atoms and hydroxyl radicals, which are produced during y-irradiation and mobilized on warming . In our previous work (Sevilla, Van Paemel and Zorman 1972), we found that the thymine anion readily protonated in 12 M LiCI as well as 8 M NaOH . Since we find that adenine does not protonate significantly in 12 M LiCI we can order the tendency toward protonation as follows ; thymine > adenine > quanine .…”

“…studies employing aqueous glasses (Holroyd and Glass 1968, Srinivasan, Singh and Gopal-Ayengar 1969, Lion and van De Vorst 1971, Sevilla, Van Paemel and Nichols 1972, Sevilla, Van Paemel and Zorman 1972 . The ion radicals of the purines have not been as thoroughly investigated partially due to the poor resolution found for their e .s .r .…”

Radicaux Libres Radioinduits Dans les Solutions Gelées de 5-méthylcytosine

“…On y distingue essentiellement un doublet caracterise par une largeur aux points d'inflexion OH T egale a 24 oersteds et un ecart hyperfin OH h egal a 16 oersteds et qui peut titre associe sans ambiguite au radical anion (RH -) . Ce OH h correspond bien a la valeur mesuree par Hiittermann, Ward et Myers (1971) pour un monocristal irradie en y, AHh =17 oersteds, eta celle rapportee par Sevilla, Van Paemel et Nichols (1972), XH h =15 oersteds, pour des verres (NaOD 8 N) de 5 methylcytosine irradies en U .V.…”

“…Cette valeur et la position respective de chacune de ces inflexions trouvent un equivalent dans le spectre du radical cation (RH+) identifie par Sevilla, Van Paemel et Nichols (1972) . Entre 145 et 195°K, le doublet central disparait progressivement et vers 185°K, it ne subsite que le multiplet represents dans la figure 2 (b) .…”