a Biotechnology Center, University of Wisconsin-Madison, Madison, Wisconsin 53706.
b Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706.
Radiat Res. 2019 May;191(5):447-459. doi: 10.1667/RR15288.1. Epub 2019 Mar 8.
To identify modifications to amino acids that are directly induced by ionizing radiation, free amino acids and 3-residue peptides were irradiated using a linear accelerator (Linac) radiotherapy device. Mass spectrometry was performed to detail the relative sensitivity to radiation as well as identify covalent, radiation-dependent adducts. The order of reactivity of the 20 common amino acids was generally in agreement with published literature except for His (most reactive of the 20) and Cys (less reactive). Novel and previously identified modifications on the free amino acids were detected. Amino acids were far less reactive when flanked by glycine residues in a tripeptide. Order of reactivity, with GVG most and GEG least, was substantially altered, as were patterns of modification. Radiation reactivity of amino acids is clearly and strongly affected by conversion of the α-amino and α-carboxyl groups to peptide bonds, and the presence of neighboring amino acid residues.
为了鉴定直接由电离辐射诱导的氨基酸修饰，使用线性加速器（Linac）放射治疗设备对游离氨基酸和 3 残基肽进行了辐照。通过质谱分析详细研究了相对辐射敏感性以及鉴定共价的、辐射依赖性加合物。20 种常见氨基酸的反应性顺序通常与已发表的文献一致，但 His（20 种中最活跃）和 Cys（反应性较低）除外。在游离氨基酸上检测到了新的和以前鉴定过的修饰。在三肽中甘氨酸残基侧翼的氨基酸反应性要低得多。反应性顺序为 GVG 最大，GEG 最小，修饰模式也发生了很大变化。氨基酸的辐射反应性显然受到α-氨基和α-羧基转化为肽键的强烈影响，以及相邻氨基酸残基的存在。
