Laboratory of Food and Regulation Biology, Graduate School of Bioscience, Tokai University, Kumamoto, Japan.
Laboratory of Food and Regulation Biology, Department of Bioscience, School of Agriculture, Tokai University, Toroku 9-1-1, Higashi-ku, Kumamoto City, Kumamoto, 862-8652, Japan.
Amino Acids. 2022 Apr;54(4):653-661. doi: 10.1007/s00726-022-03130-y. Epub 2022 Feb 15.
Cysteine is non-enzymatically modified by fumarate, which is an intermediate of the tricarboxylic acid cycle, leading to the formation of S-(2-succinyl)cysteine (2SC). Post-translational modification of physiological proteins by fumarate causes enzyme dysfunction. The aim of the study was to evaluate the changes in 2SC accumulation in physiological tissues associated with aging. Brain, liver, kidney, and serum samples were collected from 4-, 12-, and 96-week-old male C57BL/6J mice, and the level of 2SC was determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS) after pretreatment, including delipidation, protein precipitation, and hydrolysis using hydrochloric acid. The 2SC level in the brain was higher than that in other tissues, and its accumulation significantly increased with age. Similarly, N-(carboxymethyl)lysine levels, an advanced glycation end-products (AGEs) that accumulates in tissues in an age-dependent manner, was found to be increased in the brain and kidneys of elderly mice. Accumulation of N-(5-hydro-5-methyl-4-imidazolone-2-yl)-ornithine increased significantly with age, but only in the kidneys. The fumarate content in the brain was similar to that in the liver and kidney at 4 and 12 weeks of age. Furthermore, fumarate contents increased in the liver and kidney at 96 weeks of age, whereas its level did not change in the brain. Our results demonstrated that the changes in 2SC and AGEs levels in tissues reflected differing metabolism and enhanced oxidative stress in each organ; in particular, the metabolism in the brain and kidneys is highly affected by aging.
半胱氨酸可被延胡索酸（三羧酸循环的中间产物）非酶修饰，形成 S-(2-琥珀酰）半胱氨酸（2SC）。生理蛋白的延胡索酸的翻译后修饰会导致酶功能障碍。本研究旨在评估与衰老相关的生理组织中 2SC 积累的变化。从 4 周、12 周和 96 周龄雄性 C57BL/6J 小鼠中采集脑、肝、肾和血清样本，经预处理（包括脱脂、蛋白沉淀和盐酸水解）后，采用液相色谱-串联质谱法（LC-MS/MS）测定 2SC 水平。大脑中的 2SC 水平高于其他组织，且随年龄增长呈显著增加趋势。同样，在老年小鼠的大脑和肾脏中，也发现了组织中随年龄增长而积累的晚期糖基化终产物（AGEs）N-（羧甲基）赖氨酸水平升高。N-（5-羟-5-甲基-4-咪唑啉-2-基）-鸟氨酸的积累随年龄的增长而显著增加，但仅在肾脏中增加。4 周和 12 周龄时，大脑中的延胡索酸含量与肝、肾相似。此外，96 周龄时，肝、肾中的延胡索酸含量增加，而大脑中的含量没有变化。我们的结果表明，组织中 2SC 和 AGEs 水平的变化反映了每个器官代谢的不同和氧化应激的增强；特别是大脑和肾脏的代谢受衰老的影响很大。
