Stable radical in the ribose moiety of x-irradiated 3'-cytidylic acid and its relation to a similar radical in cytidine: an ESR-ENDOR study

Journal Article · Wed Dec 01 04:00:00 EST 1976 · Radiat. Res.; (United States)

DOI:https://doi.org/10.2307/3574322· OSTI ID:7127985

Bernhard, W A ^[1]; Huettermann, J; Mueller, A; Close, D M; Fouse, G W

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1. Univ., Regensburg, Ger.

A stable free radical, labeled 3..cap alpha..H, is formed in 3'-cytidylic acid (3'CMP) single crystals by x-irradiating at 77/sup 0/K and then warming to above room temperature. It remains stable up to 150/sup 0/C. ESR and ENDOR measurements explicitly indicate a structure of the form H/sub 2/C - CX = CHY. The same free radical structure is assigned to a radical in cytidine (whose spectral parameters have been analyzed by Hampton and Alexander). The chemical structures of groups N and Y are tentatively assigned for the 3..cap alpha..H radical in both 3'CMP and cytidine. Measurements on the formation of the 3..cap alpha..H radical in 3'CMP indicate that the precursor radical is due to hydrogen abstraction of C/sub 5'/. The activation energy of the conversion is ca. 30 kcal/mole. A mechanism is postulated for the formation of the 3..cap alpha..H radical in both 3'CMP and cytidine. It is shown to account for the decay of the 3..cap alpha..H radical in cytidine and the presence of yet another hitherto unassigned radical product observed by Allison and Alexander. The postulated mechanism provides a reaction scheme for arriving at various end products identified in aqueous radiolysis studies of DNA and its components.

• OSTI ID: 7127985
• Journal Information: Radiat. Res.; (United States), Journal Name: Radiat. Res.; (United States) Vol. 68:3; ISSN RAREA
• Country of Publication: United States
• Language: English

Related Subjects

560111* -- Radiation Effects on Biochemicals-- In Vitro-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AZINES
CHEMICAL RADIATION EFFECTS
CHEMISTRY
CYTIDINE
CYTIDYLIC ACID
ELECTROMAGNETIC RADIATION
ELECTRON SPIN RESONANCE
ENDOR
HETEROCYCLIC COMPOUNDS
IONIZING RADIATIONS
IRRADIATION
MAGNETIC RESONANCE
NUCLEOSIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PYRIMIDINES
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIATIONS
RADICALS
RADIOINDUCTION
RESONANCE
RIBOSIDES
X RADIATION