Yoshida H, Turner J E, Bolch W E, Jacobson K B, Garrison W M
Health and Safety Research Division, Oak Ridge National Laboratory, Tennessee 37831.
Radiat Res. 1992 Mar;129(3):258-64.
The product yields in X-irradiated aqueous solutions of glycylglycine (0.05 M and 1.0 M) were measured under deoxygenated conditions. Comparison was made between the results obtained from X- and 60Co gamma-irradiated glycylglycine solutions reported by Garrison, Sokol, and Bennett-Corniea (Radiat. Res. 53, 376-384, 1973). The mechanisms proposed by Garrison et al. were tested by evaluating the stoichiometric relationships. The two intermediate radicals, deamination and H-abstraction radicals, were produced in the initial interactions of glycylglycine with reactive species (e-aq, OH, H) formed in H2O. Although the difference was fairly large at 0.05 M, the production of deamination radicals agreed well with the consumption of the radicals at 1.0 M. The production and the consumption of H-abstraction radicals were within the estimated experimental error in dilute solutions. Among all the products only the G value of aspartic acid decreased with increasing concentration of glycylglycine. This could be attributed to the fact that more acetylglycine is formed at the expense of aspartic acid at 1.0 M than at 0.05 M glycylglycine solutions. Competitive reactions involved with deamination radicals under conditions of homogeneously distributed reactants are discussed to elucidate the radiation chemistry of glycylglycine.
在无氧条件下测量了甘氨酰甘氨酸（0.05 M和1.0 M）的X射线辐照水溶液中的产物产率。将所得结果与Garrison、Sokol和Bennett-Corniea报道的X射线和60Coγ射线辐照甘氨酰甘氨酸溶液的结果进行了比较（《辐射研究》53, 376 - 384, 1973）。通过评估化学计量关系对Garrison等人提出的机制进行了测试。甘氨酰甘氨酸与H2O中形成的活性物种（水合电子、OH、H）的初始相互作用产生了两种中间自由基，即脱氨基自由基和氢抽取自由基。尽管在0.05 M时差异相当大，但在1.0 M时脱氨基自由基的产生与自由基的消耗吻合得很好。在稀溶液中，氢抽取自由基的产生和消耗在估计的实验误差范围内。在所有产物中，只有天冬氨酸的G值随甘氨酰甘氨酸浓度的增加而降低。这可能是由于在1.0 M时，与0.05 M甘氨酰甘氨酸溶液相比，更多的乙酰甘氨酸是以天冬氨酸为代价形成的。讨论了在反应物均匀分布条件下与脱氨基自由基相关的竞争反应，以阐明甘氨酰甘氨酸的辐射化学。
