含硫醇的非必需氨基酸，氧化形成胱氨酸。膳食补充剂 a thiol-containing non-essential amino acid that is oxidized to form cystine. Dietary supplement, 养分。面团调理剂 nutrient. Dough conditioner 半胱氨酸（缩写为cys或c）是化学式为ho2cch（nh2）ch2sh的α-氨基酸。它是非必需氨基酸 Cysteine (abbreviated as Cys or C) is an ?-amino acid with the chemical formula HO2CCH(NH2)CH2SH. It is a non-essential amino acid, 这意味着它是在 类中生物合成的。它的密码子是ugu和ugc。半胱氨酸侧链是硫醇 which means that it is biosynthesized in humans. Its codons are UGU and UGC. The side chain on cysteine is thiol, 它是非极性的，因此半胱氨酸通常被分类为疏水性氨基酸。硫醇侧链经常参与酶促反应 which is nonpolar and thus cysteine is usually classified as a hydrophobic amino acid. The thiol side chain often participates in enzymatic reactions, 充当亲核试剂。硫醇易于氧化生成二硫键胱氨酸 serving as a nucleophile. The thiol is susceptible to oxidization to give the disulfide derivative cystine, 可可豆提取物可可脂提取物可可提取物55％多酚异黄酮巧克力（NFC 581a（frutarom）可可醇）62可可透明脂溶性可可提取物高级可可提取物可可提取物25倍可可提取物黑暗天然可可提取物天然可可提取物天然有机可可提取物上pg-增强深色可可提取物可可粉提取可可液提取物外提取物可可GW（德之馨）可可液体提取物可可粉提取物可可喷雾干燥粉末提取物可可皮和种子的提取物 which serves an important structural role in many proteins. Cysteine is named after cystine.; Cysteine is a very popular target for site-directed labeling experiments to investigate biomolecular structure and dynamics. Maleimides will selectively attach to cysteine using a covalent Michael addition. Site-directed spin labeling for EPR or paramagnetic relaxation enhanced NMR also uses cysteine extensively.; Cysteine is an important source of sulfide in human metabolism. The sulfide in iron-sulfur clusters and in nitrogenase is extracted from cysteine, 在该过程中将其转化为丙氨酸。绵羊需要半胱氨酸才能生产羊毛 which is converted to alanine in the process.; Cysteine is required by sheep in order to produce wool: 它是一种必需氨基酸，必须从草类食物中摄取。作为结果 it is an essential amino acid which must be taken in as food from grass. As a consequence, 在干旱条件下 during drought conditions, 绵羊停止生产羊毛；然而 sheep stop producing wool; however, 已经开发出可以产生半胱氨酸转基因绵羊。半胱氨酸 transgenic sheep which can make their own cysteine have been developed.[citation needed]; Cysteine, 主要是对映体 mainly the L-enantiomer, 是食物中的前体 is a precursor in the food, 制药业 pharmaceutical, 和个 护理行业。最大的应用之一是调味剂的生产。例如 and personal care industries. One of the largest applications is the production of flavors. For example, 半胱氨酸与糖的反应在美拉德反应中产生了肉味。 l-半胱氨酸还用作烘烤的加工助剂。少量（数十百万分之几 ppm范围内）有助于软化面团，从而减少加工时间。 http : //www.cfsan cfsan.fda.gov/〜dms ~dms/食物的 foodic;高水平的半胱氨酸 , 由于容量减少 due to its reducing capacity, 已显示在某些情况下会失活胰岛素。这是因为胰岛素包含三个二硫键 have been shown to inactivate insulin under certain conditions. This is because insulin contains three disulfide bonds, 半胱氨酸可以减少其中之一。如果发生这种情况 one of which can be reduced by cysteine. If this happens, 胰岛素失去其特征结构，从而失去功能在低血糖发作期间（血液中胰岛素过多导致血糖不安全下降），半胱氨酸可用于灭活胰岛素 insulin looses its characteristic structure and thus looses functionality. During a hypoglycemia attack (where there is too much insulin in the blood causing an unsafe drop in blood sugar) Cysteine can be used to inactivate insulin, 使血糖水平正常化。在某些情况下 allowing blood sugar levels to normalize. In some cases, 硫胺素的使用 the use of Thiamine, 维生素C vitamin C, 半胱氨酸和半胱氨酸已成功治疗严重的低血糖症。另外 and Cysteine have been successful in treating severe cases of hypoglycemia. Additionally, 由于它与胰岛素的相互作用 due to its interaction with insulin, 拟南芥模型中两个银杏1-羟基-2-甲基-2-（e）-丁烯基-4-二磷酸还原酶/异戊烯基二磷酸合成酶（hdr / ids）启动子的不同表达模式。 diabetics should avoid supplements or medications that contain cysteine or have the potential to increase cysteine levels.; In a 1994 report released by five top cigarette companies, 半胱氨酸是599种香烟添加剂之一。像大多数香烟添加剂一样 cysteine is one of the 599 additives to cigarettes. Like most cigarette additives, 然而 however, 其用途或目的是未知的。将其包含在香烟中可带来两个好处 its use or purpose is unknown. Its inclusion in cigarettes could offer two benefits: 充当祛痰药 Acting as an expectorant, 3'-二醇fitoestesina eth-f（植物性）叶黄素（植物性）叶黄素叶绿素叶黄素（万寿菊提取物）zmc天然叶黄素20％油分散体zmc天然叶黄素5％cws-szmc天然叶黄素5％得自tagetes erecta的植物叶黄素万寿菊的-trans-（+）-叶黄素叶黄素 since smoking increases mucus production in the lungs; and increasing the beneficial antioxidant glutathione (which is diminished in smokers).; N-acetyl-L-cysteine (NAC) is a derivative of cysteine wherein an acetyl group is attached to the nitrogen atom. This compound is sometimes considered as a dietary supplement, 尽管它不是理想的来源，因为它在肠中分解代谢。[需要引证] nac经常用作止咳药，因为它可以破坏粘液中的二硫键，从而使其液化 although it is not an ideal source since it is catabolized in the gut.[citation needed] NAC is often used as a cough medicine because it breaks up the disulfide bonds in the mucus and thus liquefies it, 磷脂酰胆碱（pc）是一类以胆碱为首基的磷脂。它们是生物膜的主要组成部分，可以很容易地从各种容易获得的来源中获得，例如蛋黄或大豆，可以从中机械地提取或使用己烷化学提取它们。它们还是动植物组织中存在的黄棕色脂肪物质卵磷脂组的成员。 （维基百科） making it easier to cough up. It is also this action of breaking disulfide bonds that makes it useful in thinning the abnormally thick mucus in Cystic Fibrosis patients. NAC is also used as a specific antidote in cases of acetaminophen overdose.; Oxidation of cysteine produces the disulfide cystine. More aggressive oxidants convert cysteine to the corresponding sulfinic acid and sulfonic acid. Cysteine residues play a valuable role by crosslinking proteins, 在恶劣的细胞外环境中增加了蛋白质的稳定性 which increases the protein stability in the harsh extracellular environment, 并且还具有赋予蛋白水解抗性的功能（因为蛋白质输出是一个昂贵的过程 and also functions to confer proteolytic resistance (since protein export is a costly process, 最小化其必要性是有利的）。里面的细胞 minimizing its necessity is advantageous). Inside the cell, di硫化物 sulfide 桥梁 桥 bridges between cysteine 残留物 resi到期 dues 中 wi瘦 thin a polypeptide 支持 support the 蛋白 protein's 次要的 secondary 结构体 structure. 胰岛素 Insulin is an 例 example of a 蛋白 protein with 胱氨酸 cystine 交联 crosslinking, 其中两个分开的肽链通过一对二硫键连接。 wherein two separate peptide chains are connected by a pair of disulfide bonds.