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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Calculation of Standard Reduction Potentials of Amino Acid Radicals and the Effects of Water and Incorporation into Peptides
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Calculation of Standard Reduction Potentials of Amino Acid Radicals and the Effects of Water and Incorporation into Peptides

机译：计算氨基酸自由基的标准降低电位及水的影响，掺入肽

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摘要

Guanine (Guo) is generally accepted as the most easily oxidized DNA base when cells are subjected to ionizing radiation; calculations of the standard reduction potential of the guanyl radical, E degrees(Guo(center dot+)/Guo) are within similar to 0.1 V of experimental values in aqueous solution extrapolated to standard conditions. While a number of experimental studies have shown some amino acid radicals have redox properties at pH 7 which suggest or confirm a capacity for radical "repair" by electron transfer from the amino acid to Guo(center dot+ )(or its deprotonated conjugate), the redox properties of the radicals of other amino acids, including methionine, lysine and cystine, are less well characterized. In addition, the effects of incorporation of the amino acids into peptides, or the effects of water of hydration on calculated potential's, have not been extensively studied. In this work, calculations of standard reduction potentials of radicals from model amino acids as they appear in histone proteins are performed. To predict redox properties at pH 7, acid dissociation constants (pK(a)s) of both radical and ground state amino acids are required. In some instances these are not experimentally determined and calculated pK(a)s have been derived for some common amino-acids and compared with experimental values.
机译：鸟嘌呤（过）被公认为是当细胞经历电离辐射最容易被氧化的DNA碱基;的脒基的基团的标准还原电势的计算，E度（过（中心点+）/过）是内类似于外推到标准条件水溶液0.1V的实验值。虽然一些实验研究已经显示出一些氨基酸残基具有在pH 7的氧化还原性能，其表明或从氨基酸的电子转移到过（中心点+）（或它的去质子化的缀合物）确认用于自由基“修理”的容量，所述的其它氨基酸，包括甲硫氨酸，赖氨酸和胱氨酸基团的氧化还原性质，较少充分表征。此外，氨基酸成肽，或计算潜在的结合水的影响的掺入的影响，还没有被广泛研究。在这项工作中，从模型氨基酸自由基的标准还原电位的计算，因为它们出现在组蛋白进行。为了预测在pH 7的氧化还原性能，氨基，需要的酸解离常数（pK值的（a）或多个）两者自由基和基态的。在一些情况下，这些不实验确定的和计算的pK值（一个）类已经导出了一些常见的氨基酸，并与实验值进行比较。

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