1996 Fiscal Year Final Research Report Summary
Pulse Radiolysis of 5-Substituted Uracils : Substituent Effects on Radical Reactivity
| Project/Area Number |
07651002
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
工業物理化学
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| Research Institution | UNIVERSITY OF OSAKA PREFECTURE |
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Principal Investigator |
FUJITA Shin-ichi UNIVERSITY OF OSAKA PREFECTURE,Research Institute of Advanced Technology, Professor, 先端科学研究所, 教授 (60100210)
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| Co-Investigator(Kenkyū-buntansha) |
KITAGAWA Toshikazu Kyoto Univ., Graduate School of Engineering, Lecturer, 工学研究科, 講師 (20183791)
HORII Hideo UNIVERSITY OF OSAKA PREFECTURE,Research Institute of Advanced Technology, Associ, 先端科学研究所, 助教授 (10100215)
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| Project Period (FY) |
1995 – 1996
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| Keywords | Radiation / Indirect Action / Biological Damages / Hydroxyl Radical / 5-Substituted Uracils / Addition Reaction / Substituent Effect / Pulse Radiolysis |
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| Research Abstract |
Effects of substituents on the reactivity of 5-substituted uracils were investigated experimentally and theoretically to get molecular and mechanistic insights into the biological damages by ionizing radiation. In 1995 the reaction of various 5-substituted uracils with hydroxyl radicals, which were generated as the primary active species in the radiolysis of N_2O-saturated aqueous solution, and the reactivity of intermediate radicals were explored to characterize the damages of pyrimidine bases by indirect action of radiation. In 1996 the dynamic behavior in the formation and conversion to radicals of radical cation intermediates derived from 5-substituted uracils was determined in relation to direct action of radiation, for correlating the reactivity of the intermediates with their structures. The followings are the main results.
(1) The regioselectivity of hydroxyl radical addition to the C (5)-C (6) double bond of 5-substituted uracils, that was strongly affected by the 5-substituent structures, was evaluated quantitatively by a redox titration method in the pulse radiolysis.
(2) The mechanism by which hydroxylated 5-substituted uracil-6-yl radicals undergo elimination of 5-substituents to produce hydroxyl radicals was demonstrated.
(3) The structure-reactivity relationship of radicals was determined on the basis of the experimental data from pulse and steady-state radiolyses to clarify the 5-substituent effect on the reactivity of 5-substituted uracils and the related radicals.
(4) The dynamic behavior and the reactivity of radical cations derived from one-electron oxidation of 5-substituted uracils and the related allyl radicals were characterized.
(5) The N (1) -C (5) -linked dimers of 5-substituted uracils as produced by head-to-tail recombination of the allyl radicals were quantified to clarify the 5-substituent effect on the G-value of the dimerization.
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