|sum formula||C 3 H 7 N O 2 S|
|mol mass||121.16 g/mol|
|state of aggregation||firmly|
|density||? g/cm ³|
|melting point||220-228 °C|
|boiling point||? °C|
|steam pressure||? Pa (x °C)|
|Löslichkeit||gut in Wasser (160 g/L bei 20 °C), Alkohol, Essigsäure, nicht in Ether und Benzol|
bei 25 °C
| pKCOOH: 1.8|
PC NH2: 10.8
PC Seitenkette: 8,3
|R and S-sentences||
of R: -
|as far as possible and common, are not used SI-UNITs. If not differently notes, the indicated data apply with standard conditions.|
Cystein is a schwefelhaltige proteinogen amino acid. Their Seitenkette has the structured sum formula - CH 2- Sports club. Two Cysteine can train a disulphide bridge, whereby Cystin develops. Disulphide bridges are responsible apart from hydrogen bonds , ionischen connections and van that Waals forces for the training and the receipt of the tertiary and quart acre structure of the proteins.
Table of contents
Cystein belongs to the not-essential amino acids, since it can be formed by the body. It is like Methionin a schwefelhaltige amino acid. As a component of many proteins and enzymes it often is at the catalysis mechanism taken part.
biosynthesis and Metabolismus
- Cystein become from series, which supplies the basic structure, and Methionin over Homocystein, which contributes the group of sports clubs,developed, the enzymes Cystathionin Synthetase and Cystathionase are erforerlich. Therefore series or Methioninmangel restrains the Cysteinsynthese.
- Two Cystein molecules can result from Cystin from splitting of its disulphide bridge.
- It can be diminished through α, β elimination. Aminoacrylat and H 2 S. develop. H 2 S reactsfurther to the sulfate (SO 4 ² -). Aminoacrylat can relocate to the Iminopropionat, which splits off hydrolytically its amino group and in such a way the Pyruvat becomes.
- It can become also by Transaminierung the β-Mercaptopyruvat. The sulfite Transferase helps this to raise a sulfite to the Thiosulfat it delivers its Thiol group.It becomes thereby the Pyruvat, and the Thiosulfat (S 2 O 3 ² -) dissociates to the sulfate. Pyruvat is an intermediate product of the CIT advice cycle.
- Cystein can oxidize also at the group of sports clubs and deliver whereupon its group of carboxyls, whereby it becomes Taurin, which can conjugate bile acids.
- From defects in the Cystintransporter (admission stomach intestine/Trakt, resumption kidney) a Cystinurie can result. The mutation (rBAT gene) concerns also the amino acids Lysin, arginin and Ornithin, thus the Polyamino amino acids.
the amino acid can precipitate for example silver ions as Thiolat. It becomes therefore among other thingsas therapeutic agent used for silver poisonings. Cystein is inserted by the connection of free radicals by the Thiolgruppe also for the Vorbeugung by radiation damage and with poisonings by heavy metals. It normally becomes in the form of Acetylcystein (ACC and/or. NAK) gives.
as food additiveCystein is marked by the contraction E 920. Cystein contributes to the accelerated flour maturing . This is in particular of great importance with automated baking procedures, for example for cookies. Besides Cystein/Cystin is a raw material for flavour production, in particular for meat and roasting flavours. As semiessentielle amino acid Cystein/Cystin becomes more adapted Mother's milk added. Furthermore E 920 is used with Diätzubereitungen, feeds, medicaments and Kosmetika. A declaration in finished products is not necessary.
Cystein is added to pastes, if the adhesive is too strong. Thus a softening of the adhesive is reached, the paste can be processed better. CystinE 921 causes the opposite and makes the adhesive stronger.
Cystein is used (gives as Acetylcystein) to the symptomatic therapy by coughs, in particular into the acute and convalescence phase after cold diseases. Under the gift of Cystein in the process of these illnesses one increasesformed Bronchialschleim more highly liquidly and can be so more easily coughed up.
under gift of Cystein during the training the structure of muscle is to be accelerated (anabole effect). Cystein stands therefore under suspicion, a Dopingmittel to be.
Web on the left of
|Alanine | Arginin | Asparagine | Asparagine acid | Cystein | Glutamin | Glow amine acid | Glycine | Histidin | Isoleucin | Leucin | Lysin | Methionin | Phenylalanin | Prolin | Pyrrolysin | Selenocystein | Selenomethionin | Series | Threonin | Tryptophan | Tyrosin | Valin|
|essenzielle amino acid | Protein | Peptid | Genetic code|