L-Cysteine (BioDeep_00000001666)

描述信息

Cysteine (Cys), also known as L-cysteine is an alpha-amino acid. These are amino acids in which the amino group is attached to the carbon atom immediately adjacent to the carboxylate group (alpha carbon). Amino acids are organic compounds that contain amino (–NH2) and carboxyl (–COOH) functional groups, along with a side chain (R group) specific to each amino acid. L-alanine is one of 20 proteinogenic amino acids, i.e., the amino acids used in the biosynthesis of proteins. Cysteine is found in all organisms ranging from bacteria to plants to animals. It is classified as an aliphatic, non-polar, sulfur-containing amino acid. Cysteine is an important source of sulfur in human metabolism, and although it is classified as a non-essential amino acid, cysteine may be essential for infants, the elderly, and individuals with certain metabolic disease or who suffer from malabsorption syndromes. Cysteine can occasionally be considered as an essential or conditionally essential amino acid. Cysteine is unique amongst the twenty natural amino acids as it contains a thiol group. Thiol groups can undergo oxidation/reduction (redox) reactions; when cysteine is oxidized it can form cystine, which is two cysteine residues joined by a disulfide bond. This reaction is reversible since the reduction of this disulphide bond regenerates two cysteine molecules. The disulphide bonds of cystine are crucial to defining the structures of many proteins. Cysteine is often involved in electron-transfer reactions, and help the enzyme catalyze its reaction. Cysteine is also part of the antioxidant glutathione. N-Acetyl-L-cysteine (NAC) is a form of cysteine where an acetyl group is attached to cysteines nitrogen atom and is sold as a dietary supplement. Cysteine is named after cystine, which comes from the Greek word kustis meaning bladder (cystine was first isolated from kidney stones). Oxidation of cysteine can produce a disulfide bond with another thiol and further oxidation can produce sulphfinic or sulfonic acids. The cysteine thiol group is also a nucleophile and can undergo addition and substitution reactions. Thiol groups become much more reactive when they are ionized, and cysteine residues in proteins have pKa values close to neutrality, so they are often in their reactive thiolate form in the cell. The thiol group also has a high affinity for heavy metals and proteins containing cysteine will bind metals such as mercury, lead, and cadmium tightly. Due to this ability to undergo redox reactions, cysteine has antioxidant properties. Cysteine is important in energy metabolism. As cystine, it is a structural component of many tissues and hormones. Cysteine has clinical uses ranging from treating baldness to psoriasis to preventing smokers hack. In some cases, oral cysteine therapy has proved excellent for treatment of asthmatics, enabling them to stop theophylline and other medications. Cysteine also enhances the effect of topically applied silver, tin, and zinc salts in preventing dental cavities. In the future, cysteine may play a role in the treatment of cobalt toxicity, diabetes, psychosis, cancer, and seizures (http://www.dcnutrition.com/AminoAcids/). Cysteine has been identified as a uremic toxin according to the European Uremic Toxin Working Group (PMID: 22626821).
[Spectral] L-Cysteine (exact mass = 121.01975) and D-2-Aminobutyrate (exact mass = 103.06333) were not completely separated on HPLC under the present analytical conditions as described in AC$XXX. Additionally some of the peaks in this data contains dimers and other unidentified ions.
[Spectral] L-Cysteine (exact mass = 121.01975) and Creatine (exact mass = 131.06948) were not completely separated on HPLC under the present analytical conditions as described in AC$XXX. Additionally some of the peaks in this data contains dimers and other unidentified ions.
Detoxicant, dietary supplement, dough strengthener, yeast nutrient for leavened bakery products. Flavouring agent. Enzymic browning inhibitor. L-Cysteine is found in many foods, some of which are bilberry, mugwort, cowpea, and sweet bay.

L-(+)-Cysteine. CAS Common Chemistry. CAS, a division of the American Chemical Society, n.d. https://commonchemistry.cas.org/detail?cas_rn=52-90-4 (retrieved 2024-07-01) (CAS RN: 52-90-4). Licensed under the Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0).
L-Cysteine is a conditionally essential amino acid, which acts as a precursor for biologically active molecules such as hydrogen sulphide (H2S), glutathione and taurine. L-Cysteine suppresses ghrelin and reduces appetite in rodents and humans[1].
L-Cysteine is a conditionally essential amino acid, which acts as a precursor for biologically active molecules such as hydrogen sulphide (H2S), glutathione and taurine. L-Cysteine suppresses ghrelin and reduces appetite in rodents and humans[1].

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