L-システイン 化学特性,用途語,生産方法
外観
白色、結晶～結晶性粉末
定義
本品は、次の化学式で表されるアミノ酸である。
溶解性
水に溶けやすく、エタノール(99.5)にほとんど溶けない。
解説
天然のR(L)形は分解点178 ℃．[α]25D－16.5°(水)．pK1 1.71，pK2 8.33，pK3 10.78．水，エタノール，氷酢酸，アンモニア水に易溶，ほかの有機溶媒に難溶．微量の金属の存在下ではとくに不安定で，空気酸化されてシスチンにかわる．解毒剤や食用補剤に用いられる．LD50 1890 mg/kg(ラット，経口)．
森北出版「化学辞典（第2版）
用途
SH 基を有する化合物です。 粘液ムコタンパクのジスルフィド結合を解離 する作用を示します。
用途
SH 基を有する化合物です。
粘液ムコタンパクのジスルフィド結合を解離
する作用を示します。
用途
化粧品、食品の添加物、酸化防止剤
化粧品の成分用途
パーマネント.ウェーブ用還元剤、ヘアコンディショニング剤、還元剤、皮膚コンディショニング剤、酸化防止剤
製造
L-システイン,略号CysまたはC．含硫アミノ酸の一つ．タンパク質構成アミノ酸として広く分布しているが，シスチンの形で含まれることが多い．しかし，酵素分子中でチオール基が活性中心としてはたらくこともある．シスチンから液体アンモニア中ナトリウムで還元すると得られる．
効能
スルフヒドリル酵素活性化薬
使用上の注意
不活性ガス封入
説明
Cysteine (abbreviated as Cys or C) is an α-amino acid with the chemical formula HO
2CCH(NH
2)CH
2SH. It is a semi - essential amino acid, which means that it can be biosynthesized in humans. The thiol side chain in cysteine often participates in enzymatic reactions, serving as a nucleophile. The thiol is susceptible to oxidization to give the disulfide derivative cystine, which serves an important structural role in many proteins. When used as a food additive, it has the E number E920.
化学的特性
A sulfur-containing amino acid, metabolically related to methionine. Methionine is the source of sulfur atom in the
synthesis of cysteine in the body. Chemically, L-cysteine is L-2-amino-mercaptopropionic acid. Cysteine has a sulfureous aroma. It
is a nutrient and is used in dietary supplements.
物理的性質
Solubility 28 (25 ℃) g/100 mL solution, 16 (20 ℃) g/100 g H2O, pI 5.02, dissociation constants: pK1 1.71, pK2 8.27 (–SH), pK3 10.78.
天然物の起源
Dietary sources Although classified as a non-essential amino acid, in rare cases, cysteine may be essential for infants, the elderly, and individuals with certain metabolic disease or who suffer from malabsorption syndromes. Cysteine can usually be synthesized by the human body under normal physiological conditions if a sufficient quantity of methionine is available.
Cysteine is catabolized in the gastrointestinal tract and blood plasma. In contrast, cystine travels safely through the GI tract and blood plasma and is promptly reduced to the two cysteine molecules upon cell entry.
Industrial sources The majority of L - cysteine is obtained industrially by hydrolysis of poultry feathers or human hair. Synthetically produced L-cysteine, compliant with Jewish Kosher and Muslim Halal rules, is also available, albeit at a higher price. The synthetic route involves fermentation utilizing a mutant of E. coli.
Biosynthesis In animals, biosynthesis begins with the amino acid serine. The sulfur is derived from methionine, which is converted to homocysteine through the intermediate S- adenosylmethionine. Cystathionine betasynthase then combines homocysteine and serine to form the asymmetrical thioether cystathionine. The enzyme cystathionine gamma-lyase converts the cystathionine into cysteine and alphaketobutyrate.
使用
L-Cysteine is a non-essential amino acid that can be synthesized by the human body under normal physiological conditions if a sufficient quantity of methionine is available. L-Cysteine is commonly used as a precursor in the food and pharmaceutical industries. L-Cysteine is used as a processing aid for baking, as an additive in cigarettes, as well as in the preparation of meat flavours. It is used in foods to prevent oxygen from destroying vitamin c and is used in doughs to reduce mixing time.
主な応用
Cysteine, mainly the L-enantiomer, is a precursor in the food, pharmaceutical, and personal care industries. One of the largest applications is the production of flavors. For example, the reaction of cysteine with sugars in a Maillard reaction yields meat flavors. Lcysteine is also used as a processing aid for baking.
In the field of personal care, cysteine is used for permanent wave applications predominantly in Asia. Again the cysteine is used for breaking up the disulfide bonds in the hair's keratin.
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 essential amino acid obtained by fermentation. Cysteine is a component of the skin’s natural moisturizing factor and can help normalize oil gland secretion because of its sulfur content. It is also said to promote wound healing. In addition, studies indicate that cysteine helps increase levels of glutathione (an anti-oxidant) in the body. It is considered beneficial in treating oily skin.
製造方法
L-Cysteine used to be produced almost exclusively by hydrolysis of hair or other keratins. The amino acid isolated was l-cystine, which was reduced electrolytically to l-cysteine. L-Cysteine has also been prepared from beta-chloro-d,l-alanine and sodium sulfide with cysteine desulfhydrase, an enzyme obtained from, e.g., Citrobacterium freundii. Today, however, the main processes for cysteine production are biological. A direct fermentation process has been developed for the manufacture of l-cystine, using a modified Escherichia coli bacterium. The technology has been extended to prepare other modified l-cysteine analogues. An enzymatic process for l-cysteine has been successfully developed using microorganisms capable to hydrolyze 2-amino-delta2-thiazoline 4-carboxylic acid (ATC) which is readily available from methyl alpha-chloroacrylate and thiourea. A mutant of Pseudomonas thiazolinophilum converts d,l-ATC to l-cysteine in 95% molar yield at product concentrations higher than 30 g/L.
定義
ChEBI: L-cysteine is an optically active form of cysteine having L-configuration. It has a role as a flour treatment agent, a human metabolite and an EC 4.3.1.3 (histidine ammonia-lyase) inhibitor. It is a serine family amino acid, a proteinogenic amino acid, a cysteine and a L-alpha-amino acid. It is a conjugate base of a L-cysteinium. It is a conjugate acid of a L-cysteinate(1-). It is an enantiomer of a D-cysteine. It is a tautomer of a L-cysteine zwitterion.
一般的な説明
L-cysteine is a sulfur-containing non-essential amino acid. Its ability to reduce colitis symptoms is being assessed for potential use in treating inflammatory bowel disease (IBD).
副作用
Cysteine has been proposed as a preventative or antidote for some of the negative effects of alcohol, including liver damage and hangover. It counteracts the poisonous effects of acetaldehyde, which is the major by - product of alcohol metabolism and is responsible for most of the negative aftereffects and long - term damage associated with alcohol use (but not the immediate effects of drunkenness). Cysteine supports the next step in metabolism, which turns acetaldehyde into the relatively harmless acetic acid. In a rat study, test animals received an LD
50 dose of acetaldehyde. Those that received cysteine had an 80 % survival rate; when both cysteine and thiamine were administered, all animals survived . There is not yet direct evidence for or against its effectiveness in humans who consume alcohol at normal levels.
N-Acetylcysteine N - Acetyl - L - cysteine (NAC) is a derivative of cysteine wherein an acetyl group is attached to the nitrogen atom. This compound is sold as a dietary supplement and used as an antidote in cases of acetaminophen overdose, and obsessive compulsive disorders such as trichotillomania.
安全性プロファイル
Moderately toxic by
ingestion, intraperitoneal, and subcutaneous
routes. Experimental reproductive effects.
Human mutation data reported. When heated to decomposition fumes of SO and NO.
純化方法
Purify it by recrystallisation from H2O (free from metal ions) and dry it in a vacuum. It is soluble in H2O, EtOH, Me2CO, EtOAc, AcOH, *C6H6 and CS2. Acidic solutions can be stored under N2 for a few days without deterioration. [For synthesis and spectra see Greenstein & Winitz Chemistry of the Amino Acids (J. Wiley) Vol 3 p1879 1961, Beilstein 4 III 1618, 4 IV 3144.]
L-システイン 上流と下流の製品情報
原材料
準備製品