Cysteine
Cysteine (abbreviated as Cys or C)[1] is an α-amino acid. It has the chemical formula HO2CCH(NH2)CH2SH.
| Names | |
|---|---|
| IUPAC name
Cysteine
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| Other names
2-Amino-3-sulfhydrylpropanoic acid
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Cysteine is a semi-essential amino acid, which means that humans can make it.[2] The codons UGU and UGC code for cysteine. The thiol side chain in cysteine often does enzyme reactions as a nucleophile. The thiol oxidises to give the disulfide derivative cystine, which is important in many protein structures. When used as a food additive, cysteine has the E number E920.
Cysteine Media
Cysteine ball and stick model spinning
(R)-Cysteine (left) and (S)-Cysteine (right) in zwitterionic form at neutral pH
Cysteine synthesis: Cystathionine beta synthase catalyzes the upper reaction and cystathionine gamma-lyase catalyzes the lower reaction.
Figure 2: Cystine (shown here in its neutral form), two cysteines bound together by a disulfide bond
References
- ↑ Nomenclature and symbolism for amino acids and peptides (IUPAC-IUB Recommendations 1983). Pure Appl. Chem. 56 (5), 1984: 595–624.
- ↑ The primary structure of proteins is the amino acid sequence. The Microbial WorldUniversity of Wisconsin-Madison Bacteriology Department. Retrieved 16 September 2012.