EPR and ENDOR study of radiation-induced radical formation in purines: hypoxanthine hydrochloride monohydrate crystals X-irradiated at 10 K.

EPR and ENDOR study of radiation-induced radical formation in purines: hypoxanthine hydrochloride monohydrate crystals X-irradiated at 10 K. Research Abstract Details 

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EPR and ENDOR study of radiation-induced radical formation in purines: hypoxanthine hydrochloride monohydrate crystals X-irradiated at 10 K. Abstract Text:

Sibel Tokdemir,William H Nelson,

Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) study of hypoxanthine.HCl.H(2)O crystals irradiated at low temperatures (10 K) identified three radical species. In these crystals, the parent molecules exist in a cationic form with a proton at N7. R1 was the product of net hydrogen addition to N3 and exhibited alpha-proton hyperfine couplings to HC2, HN1, HC8, and HN3. The coupling to HC2 has an isotropic component smaller than usual, evidently an indication that the bonds to C2 are nonplanar. R2 was the product of net hydrogen loss from N7, equivalent to the one-electron oxidation product of neutral hypoxanthine, and exhibited alpha-proton hyperfine couplings to HC2 and HC8. Both couplings are characteristic of planar bonding arrangements at the centers of spin. R3 was provisionally identified as the product of net hydrogen addition to O6 and exhibited hyperfine alpha-proton couplings to HC8 and NH1. To identify the set of radicals, the experiments employed four crystal types: normal, deuterated only at NH positions, deuterated at HC8 and NH positions, and deuterated at HC8 only. The low-temperature data also showed clear evidence for H/D isotope effects in formation and/or stabilization of all radicals. To aid and support the identifications, the experimental results were compared to DFT calculations performed on a variety of radical structures plausible for the parent molecule and molecular packing within the crystal.

EPR and ENDOR study of radiation-induced radical formation in purines: hypoxanthine hydrochloride monohydrate crystals X-irradiated at 10 K. Publishing Authors By Initials

S Tokdemir,WH Nelson,

For similar heterocyclic compounds: heterocyclic compounds, 2-ring: purines research abstracts see: heterocyclic compounds: heterocyclic compounds, 2-ring: purines research

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EPR and ENDOR study of radiation-induced radical formation in purines: hypoxanthine hydrochloride monohydrate crystals X-irradiated at 10 K. Journal Published:

PUBLICATION TYPE: Research Support, N.I.H., Extr

Journal: The journal of physical chemistry. A

VOLUME: 109

Page Numbers: 8732-44

Journal Abbreviation:

ISSN: 1089-5639

DAY: 6

MONTH: Oct

YEAR: 2005

EPR and ENDOR study of radiation-induced radical formation in purines: hypoxanthine hydrochloride monohydrate crystals X-irradiated at 10 K. Information

Number of References:

LANGUAGE: eng

NlmUniqueID: 9890903

EPR and ENDOR study of radiation-induced radical formation in purines: hypoxanthine hydrochloride monohydrate crystals X-irradiated at 10 K. Keywords Mesh Terms:

KEYWORDS: Purines

MESH TERMS: chemistry

Chemical & Substance for Abstract: EPR and ENDOR study of radiation-induced radical formation in purines: hypoxanthine hydrochloride monohydrate crystals X-irradiated at 10 K. Information

Substance Name: Hypoxanthine

Registry Number: 68-94-0

Grant and Affiliation Information for EPR and ENDOR study of radiation-induced radical formation in purines: hypoxanthine hydrochloride monohydrate crystals X-irradiated at 10 K.

AFFILIATION: Department of Physics and Astronomy, Georgia State University, P.O. Box 4106, Atlanta, GA 30302-4106, USA.

Country: United States

AGENCY: United States NCI

GRANT: CA 36810

ACRONYM: CA

MEDLINETA: J Phys Chem A

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