Electron gain and electron loss radicals stabilized on the purine and pyrimidine of a cocrystal exhibiting base-base interstacking: ESR-ENDOR of X-irradiated adenosine:5-bromouracil

Journal Article · Mon Jan 31 23:00:00 EST 1983 · Radiat. Res.; (United States)

DOI:https://doi.org/10.2307/3575980· OSTI ID:5683045

Kar, L; Bernhard, W A

The predominant free radicals trapped in cocrystals of adenosine:5-bromouracil X-irradiated at 12/sup 0/K were identified by ESR-ENDOR spectroscopy and the radical reactions were followed upon annealing to 480/sup 0/K. The dominant electron abstraction and electron addition products stabilized on the bases at 12/sup 0/K are observed to be the bromouracil ..pi..-cation and the adenine ..pi..-cation and ..pi..-anion. The formation of an anion on bromouracil is inferred from the presence of a radical formed by deuterium addition to C/sub 6/ of bromouracil at higher temperatures. Above 40/sup 0/K the bromouracil ..pi..-cation appears to decay by recombination and is reduced to undetectable levels at approx.170/sup 0/K. Both adenine ..pi..-ions are also observed to decay within the same temperature range. Above 200/sup 0/K hydrogen adducts are stabilized on the bases. Experiments using partially deuterated cocrystals indicate that the H-adducts are formed via both hydrogen addition and protonation of the respective anions. Two hydrogen abstraction radicals stabilized on the sugar residue are detectable at temperatures above 200/sup 0/K, but these may be present at much lower temperatures. The results presented here question the generally accepted hypothesis that, in the presence of purine:pyrimidine stacking interactions, holes are predominantly transferred to the purines while electrns are predominantly transferred to the pyrimidines.

• Research Organization: Univ. of Rochester, NY
• OSTI ID: 5683045
• Journal Information: Radiat. Res.; (United States), Journal Name: Radiat. Res.; (United States) Vol. 93:2; ISSN RAREA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400600 -- Radiation Chemistry
560111* -- Radiation Effects on Biochemicals-- In Vitro-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ADDUCTS
ANTIMETABOLITES
AZINES
BROMOURACILS
CHEMICAL RADIATION EFFECTS
CHEMISTRY
DATA
DRUGS
ELECTROMAGNETIC RADIATION
ELECTRON SPECTRA
ELECTRON SPIN RESONANCE
ENDOR
EXPERIMENTAL DATA
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
INFORMATION
IONIZING RADIATIONS
MAGNETIC RESONANCE
NUMERICAL DATA
ORGANIC BROMINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PYRIMIDINES
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIATIONS
RESONANCE
SPECTRA
STRUCTURAL CHEMICAL ANALYSIS
URACILS
X RADIATION