Skeletal formula of cystine formed from L-cysteine (under biological conditions) Ball-and-stick model of cystine with the disulfide bond shown in yellow
Cystine Image File history File links Download high resolution version (1897x2415, 42 KB) Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Cysteine Cystine ... Image File history File links Download high resolution version (1897x2415, 42 KB) Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Cysteine Cystine ... A skeletal formula is a three-dimensional model of the molecule that demonstrates the molecular shape, including bond angles. ... armchair conformational isomerism of Cyclohexane. ...
Systematic (IUPAC) name
Cystine
Identifiers
PubChem	?
Chemical data
Formula	C6H12N2O4S2
Molar mass	240.30
Complete data

Cystine is the amino acid formed when of a pair of cysteine molecules are joined by a disulfide bond. It is described by the formula (SCH₂CH(NH₂)CO₂H)₂. It is a colorless solid, and melts at 247-249 °C. It was discovered in 1810 by William Hyde Wollaston but was not recognized as a component of proteins until it was isolated from the horn of a cow in 1899.^[1] Through formation of disulfide bonds within and between protein molecules, cystine is a significant determinant of the tertiary structure of most proteins. Disulfide bonding, along with hydrogen bonding and hydrophobic interactions is partially responsible for the formation of the gluten matrix in bread. Human hair contains approximately 5% cystine by mass.^[2] IUPAC nomenclature is a systematic way of naming organic chemical compounds. ... PubChem is a database of chemical molecules. ... A chemical formula is an easy way of expressing information about the atoms that constitute a particular chemical compound. ... For other uses, see Carbon (disambiguation). ... This article is about the chemistry of hydrogen. ... General Name, symbol, number nitrogen, N, 7 Chemical series nonmetals Group, period, block 15, 2, p Appearance colorless gas Standard atomic weight 14. ... This article is about the chemical element and its most stable form, or dioxygen. ... This article is about the chemical element. ... Molar mass is the mass of one mole of a chemical element or chemical compound. ... This article is about the class of chemicals. ... Cysteine is a naturally occurring, sulfur-containing amino acid that is found in most proteins, although only in small quantities. ... In chemistry, a disulfide is an ion formed by sulfur atoms. ... William Hyde Wollaston William Hyde Wollaston FRS (August 6, 1766 – December 22, 1828) was an English chemist and physicist who is famous for discovering two chemical elements and for developing a way to process platinum ore. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... For other uses, see Horn. ... COW is an acronym for a number of things: Can of worms The COW programming language, an esoteric programming language. ... Year 1899 (MDCCCXCIX) was a common year starting on Sunday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Friday [1] of the 12-day-slower Julian calendar). ... In biochemistry and chemistry, the tertiary structure of a protein or any other macromolecule is its three-dimensional structure, as defined by the atomic coordinates. ...

Properties

The disulfide link is readily reduced to give the corresponding thiol, cysteine. This reaction is typically effected with thiols such as mercaptoethanol or dithiothreitol. Dithiothreitol (DTT) is the common name for a small-molecule redox reagent known as Clelands reagent. ...

(SCH₂CH(NH₂)CO₂H)₂ + 2 RSH → 2 HSCH₂CH(NH₂)CO₂H + RSSR

Sulphydryl // In organic chemistry, a thiol is a compound that contains the functional group composed of a sulfur atom and a hydrogen atom (-SH). ...

Nutritional sources

Supplemental N-acetyl cysteine is claimed to be a source of cystine, but the dose of this supplement is limited by side effects. One of the richest nutritional sources of cystine in the diet is undenatured whey proteins from milk. The disulfide-bonded cystine is not digested or significantly hydrolized by the stomach, but is transported by the blood stream to the tissues of the body. Here, within the cells of the body, the weak disulfide bond is cleaved to give cysteine, from which glutathione can be synthesized. Acetylcysteine (rINN) (IPA: ), also known as N-acetylcysteine (abbreviated NAC), is a pharmacological agent used mainly as a mucolytic and in the management of paracetamol overdose. ... Irreversible egg protein denaturation and loss of solubility, caused by the high temperature (while cooking it) Denaturation is the alteration of a protein or nucleic acids shape through some form of external stress (for example, by applying heat, acid or alkali), in such a way that it will no... Glutathione (GSH) is a tripeptide. ...

In animal feed

Disulfide bonds can be broken at temperatures above about 150 °C, especially at low moisture levels (below about 20%)^[3]. For other uses, see Celsius (disambiguation). ...

Side effects

Nutritional sources of cystine are virtually free of the toxic side effects associated with the single molecule of cysteine, N-acetyl cysteine. The greatest dietary source of cystine is bio-active, unpasteurized or low-heat pasteurized undenatured whey proteins.^{[citation needed]}

See also

• Cystinuria
• Cysteine

Ë Cystinuria is an inherited autosomal recessive disorder and is characterized by the formation of cystine stones in the kidneys, ureter, and bladder. ... Cysteine is a naturally occurring, sulfur-containing amino acid that is found in most proteins, although only in small quantities. ...

References

1. ^ "cystine." Encyclopædia Britannica. 2007. Encyclopædia Britannica Online. 27 July 2007 www.britannica.com/eb/article-9028437/cystine
2. ^ Gortner, R. A.; W. F. Hoffman, W. F. (1941). "l-Cystine". Org. Synth.; Coll. Vol. 1: 194. 
3. ^ M.A. Aslaksena, O.H. Romarheima, T. Storebakkena and A. Skrede (28 June 2006). "Evaluation of content and digestibility of disulfide bonds and free thiols in unextruded and extruded diets containing fish meal and soybean protein sources". Animal Feed Science and Technology 128 (3-4): 320-330. 

Organic Syntheses is a scientific journal that Since 1921 has provided the chemistry community with annual collections of detailed and checked procedures for the organic synthesis of organic compounds. ...

External links