RECENT ADVANCES IN MECHANISMS OF RADIATION PROTECTION AND SENSITIZATION
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RECENT ADVANCES IN MECHANISMS OF RADIATION PROTECTION AND SENSITIZATION
Journal of Radiation Research and Radiation ProcessingVol. 1, Issue 1, Pages: 26-34(1983)
作者机构:
1.中国科学院上海原子核研究所
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Lin Nianyun. RECENT ADVANCES IN MECHANISMS OF RADIATION PROTECTION AND SENSITIZATION. [J]. Journal of Radiation Research and Radiation Processing 1(1):26-34(1983)
DOI:
Lin Nianyun. RECENT ADVANCES IN MECHANISMS OF RADIATION PROTECTION AND SENSITIZATION. [J]. Journal of Radiation Research and Radiation Processing 1(1):26-34(1983)DOI:
RECENT ADVANCES IN MECHANISMS OF RADIATION PROTECTION AND SENSITIZATION
Concerning the primary radiation processes of DNA and radiation modifiers a fast radiation protection mechanism — charge transfer protection hay been supposed. Some binary molecular mixtures, such as thymine-cysteine, thymine-histidine or arginine, dTMP-caffeic acid, DNA-caffeic acid etc. have been studied in detail by means of ESR and other related methods. A proposed general scheme involves basically charge transfer oxidation/reduction processes. If the electron affinity (EA)of protector (P) or sensitizer(s) is larger than target molecule (TH), i. e.,EA,P.S,>,EA,TH,(Ⅰ) and IP,P.S,≲IP,TH,(Ⅱ), thus, (Ⅰ) and (Ⅱ) may behave additively to protect TH. On the contrary, if IP,P.S,≳IP,T,H(Ⅲ), then, (Ⅰ) and (Ⅲ) may behave synergistically to sensitize the damage of TH. The common characteristic of charge transfer protection and sensitization is (Ⅰ) and their criterions are (Ⅰ) and (Ⅲ), that is to say, the charge transfer protector is a substance with higher ,EA, but lower IP than TH. However, charge transfer sensitizer is a substance with both higher ,EA, and IP than TH. In accord with above scheme we have found a qualitative rule relating the radiation protection effect to the linear molecular size of linear aromatic homologs: the larger the molecular size, the lower the IP, the higher the EA, thus, the higher the transfer efficiency through charge transfer to these aromatic protectors. These linear aromatic homologs may be examined as a model of charge transfer protector to suppress chemical carcinogenesis and protect the radiolysis of TBP-alkane extraction system. Furthermore, development of H-transfer paocess has been achieved based on the detailed examination of thymine-cysteine and thymine-AET. Further exploration of excitation transfer between thymine and aromatic amino acid has also been demonstrated.