Metabolism / Metabolites
L-cysteine is a core compound in human sulfur metabolism. In proteins, the formation of disulfide bonds between cysteine sulfhydryl groups plays a crucial role in protein tertiary structure and enzyme activity; however, cysteine is always incorporated into polypeptide chains in its cysteine form. L-cysteine is degraded to pyruvate in two steps: desulfurization and transamination. Cysteine can be metabolized to taurine and carbon dioxide via the cysteine sulfinate pathway, the first step of which is the oxidation of cysteine to cysteine sulfinate. This step is catalyzed by cysteine dioxygenase. Cysteine sulfinate can be decarboxylated to taurine, or metabolized to pyruvate and sulfite via the putative intermediate β-sulfinylpyruvate, ultimately producing carbon dioxide and sulfate. Amino acid catabolism is essential for regulating the size of the free amino acid pool and participates in energy production and nutrient reuse. The carbon skeleton is typically converted into precursors or intermediates of the tricarboxylic acid cycle. For cysteine, the reduced sulfur derived from the thiol group must also be oxidized to prevent its accumulation to toxic concentrations. This article introduces a mitochondrial sulfur catabolism pathway that catalyzes the complete oxidation of L-cysteine to pyruvate and thiosulfate. After L-cysteine is transaminated to 3-mercaptopyruvate, its thiol group is transferred to glutathione via thiotransferase 1 and oxidized to sulfite by the sulfur dioxygenase ETHE1. Subsequently, thiotransferase 1 converts sulfite to thiosulfate by adding a second persulfate group. This pathway is most important in early embryonic development and vegetative growth under light-limited conditions. Characterization of T-DNA insertion mutants of Arabidopsis thaliana ETHE1 and thiotransferase 1 revealed that intermediates in the ETHE1-dependent pathway (likely persulfates) interfere with amino acid catabolism and induce early senescence.

[1]. L-cysteine suppresses ghrelin and reduces appetite in rodents and humans. Int J Obes (Lond). 2015 Mar;39(3):447-55.

L-cysteine hydrochloride is a hydrochloride salt prepared by reacting L-cysteine with an equimolar amount of hydrogen chloride. It can be used as an EC 4.3.1.3 (histidine ammonia-lyase) inhibitor, a flour treatment agent, and a human metabolite. It contains L-cysteine. Cysteine is a thiol-containing non-essential amino acid that oxidizes to cystine. Cysteine is an essential sulfur-containing amino acid related to cystine. Cysteine is crucial for protein synthesis, detoxification, and various metabolic functions. It is found in β-keratin, the main protein in nails, skin, and hair. Cysteine is essential for collagen production and skin elasticity and texture. Cysteine is also essential for the synthesis of the amino acid taurine, is a component of the antioxidant glutathione, and plays a role in the metabolism of important biochemicals such as coenzyme A, heparin, and biotin. (NCI04) A thiol-containing non-essential amino acid that oxidizes to cysteine. See also: Cysteine (with active moiety)... See more...

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Drug Indications
For the prevention of liver and kidney damage caused by acetaminophen overdoseMechanism of Action
Under normal physiological conditions, the human body can usually synthesize cysteine if methionine is sufficient. Cysteine is usually synthesized in the human body when methionine is sufficient. Cysteine has antioxidant properties and participates in redox reactions. The antioxidant properties of cysteine are usually reflected in the tripeptide glutathione, which is present in the human body and other organisms. Due to its limited systemic availability, glutathione (GSH) usually requires biosynthesis from its constituent amino acids—cysteine, glycine, and glutamate. Glutamate and glycine are abundant in the diets of most industrialized countries, but the supply of cysteine may be a limiting substrate. In human metabolism, cysteine participates as a precursor in the formation of iron-sulfur clusters and sulfides in nitrogenase. In 1994, a report released by five top cigarette companies revealed that cysteine was one of 599 additives in cigarettes. However, like most cigarette additives, its use or purpose remains unclear. Adding cysteine to cigarettes may offer two benefits: firstly, as an expectorant, since smoking increases the production of mucus in the lungs; and secondly, by increasing the levels of the beneficial antioxidant glutathione (smokers have lower levels of glutathione in their bodies).

C3H8CLNO2S

157.6191

156.996

52-89-1

60960

White to off-white solid powder

293.9ºC at 760 mmHg

140-142ºC

131.5ºC

0.83

4

4

2

8

75.3

1

C([C@@H](C(=O)O)N)S.Cl

IFQSXNOEEPCSLW-DKWTVANSSA-N

InChI=1S/C3H7NO2S.ClH/c4-2(1-7)3(5)6;/h2,7H,1,4H2,(H,5,6);1H/t2-;/m0./s1

(2R)-2-amino-3-sulfanylpropanoic acid;hydrochloride

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)