中文摘要：

半胱氨酸（Cys）是一种半必需氨基酸,是构成体内重要抗氧化物质谷胱甘肽（GSH）的主要成分,对机体抗氧化和自由基消除功能十分重要。组织中Cys的浓度通过调节Cys生成和有效移除巯基维持在较低水平。Cys和蛋氨酸（Met）新陈代谢调节可以在维持Cys低水平的同时,保证巯基作为它们基本功能的充足供应。Cys是多种合成和分解代谢酶的底物,主要被肝Cys二氧酶（CDO）调节。CDO以Cys敏感方式被上调,主要是通过降低蛋白泛素化比率,从而降低26S蛋白酶体介导的蛋白降解。该文对Cys的摄入、新陈代谢途径以及免疫与抗氧化功能作一简要综述。

英文摘要：

Cysteine（Cys）is a semiessential amino acids.It is also an indispensable composition of glutathione（GSH） which is important for function of oxidation resistance and removal of free radicals.Tissue concentrations of Cys is maintained at low levels by regulated production and efficient removal of these thiols.The regulation of the metabolism of Cys and methionine（Met） is discussed from the standpoint of maintaining low levels of Cys while,at the same time,ensuring an adequate supply of these thiols for its essential functions.Cys is substrate for a variety of anabolic and catabolic enzymes.Its concentration is regulated primarily by hepatic Cys dioxygenase（CDO）;the level of CDO is upregulated in a Cys-responsive manner via a decrease in the rate of polyubiquitination and,hence,degradation by the 26S proteasome.In this paper,the intake,metabolism,immunity and antioxidant function of Cys are reviewed.