L-Cystein

-2.49

log Kow = -2.49

-2.49

Colorless crystals

White crystals

277000

Freely soluble in water

Freely soluble in alcohol, acetic acid, ammonia water; insoluble in ether, acetone, ethyl acetate, benzene, carbon disulfide, carbon tetrachloride

Water solubility (per g/100 g H2O): 28 g/100 mL of solution at 25 °C; 16 g/100 mL of solution at 20 °C

277 mg/mL at 25 °C

Very soluble in water and acetic acid; Insoluble in ether, acetone and benzene

240

260 °C decomposes

220 °C

Decomposes 175-178 °C; soluble in water, alcohol, acetone; the aqueous solution is acid; decomposes and oxidizes slowly; hygroscopic. Specific optical rotation: +5.0 °C (5 N HCl) at 25 °C/D; +10.0 °C at 25 °C/D (glacial acetic acid) /Cysteine hydrochloride/

Specific optical rotation: +6.5 deg at 25 °C/D (5 N HCl); +13.0 deg at 25 °C/D (glacial acetic acid)

Specific optical rotation: +9.7 deg (c = 8 in 1M HCl) at 25 °C/D

Colorless or white solid; [HSDB] Colorless crystalline solid; [Sigma-Aldrich MSDS]

Solid

White crystals; Sulferous aroma

Stable under recommended storage conditions.

In neutral or slightly alkaline aq solns it is oxidized to cystine by air. More stable in acidic solns.

Positive

1.24

2.7

Agilent XCT

Electrospray ionization

formic acid (5.3nM)

1.71

pK1 1.71 /carboxylic/; pK2 8.33 /amine/; pK3 10.78 /sulfide/

151.34 Ų [M+Na]+ [CCS Type: DT; Method: stepped-field]；149.57 Ų [M+H]+ [CCS Type: DT; Method: stepped-field]；144.47 Ų [M-H]- [CCS Type: DT; Method: stepped-field]

113 Ų [M+H]+ [CCS Type: TW; Method: calibrated with polyalanine]

148.6 Ų [M+H]+；150.4 Ų [M+Na]+；144 Ų [M-H]-

This chemical does not meet GHS hazard criteria for 33.8% (179 of 529) of reports.

Warning

H302 (55.6%): Harmful if swallowed [Warning Acute toxicity, oral]；H315 (11.9%): Causes skin irritation [Warning Skin corrosion/irritation]；H319 (11.9%): Causes serious eye irritation [Warning Serious eye damage/eye irritation]；H335 (11.9%): May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation]

P261, P264, P264+P265, P270, P271, P280, P301+P317, P302+P352, P304+P340, P305+P351+P338, P319, P321, P330, P332+P317, P337+P317, P362+P364, P403+P233, P405, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 529 reports by companies from 14 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.；Reported as not meeting GHS hazard criteria per 179 of 529 reports by companies.；There are 12 notifications provided by 350 of 529 reports by companies with hazard statement code(s).；Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown. For more detailed information, please visit ECHA C&L website.

Chemical: L-Cysteine

Regulation (EC) No 1831/2003 (amended)

Reg. (EU) 2020/642

Status: Active Update: 10-11-2020 https://echa.europa.eu/registration-dossier/-/registered-dossier/12475；Status: Active Update: 30-01-2019 https://echa.europa.eu/registration-dossier/-/registered-dossier/23057

Cysteine: Does not have an individual approval but may be used under an appropriate group standard

Cysteine used as a nutrient and/or dietary supplement in animal drugs, feeds, and related products is generally recognized as safe when used in accordance with good manufacturing or feeding practice.

Substance added directly to human food affirmed as generally recognized as safe (GRAS).

The food additive amino acids may be safely used as nutrients added to foods in accordance with the following conditions: (a) The food additive consists of one or more of the following individual amino acids in the free, hydrated, or anhydrous form, or as the hydrochloride, sodium, or potassium salts. L-Cysteine is included on this list.

Residues of cysteine are exempted from the requirement of a tolerance when used in accordance with good agricultural practice as inert (or occasionally active) ingredients in pesticide formulations applied to growing crops only. Use: Synergist. Limit: Maximum of 0.5% of formulation.

Acute Tox. 4 (55.6%)；Skin Irrit. 2 (11.9%)；Eye Irrit. 2 (11.9%)；STOT SE 3 (11.9%)

Acute toxicity (ingestion) - category 4

Acute toxicity (Oral) - Category 4

... A single ocular application of the test item L-Cysteine to rabbits at a dose of 0.1 g produced slight irritant effects, which were fully reversible within 48 hours. ...

... The single dermal application of the test item L-Cysteine to three rabbits at a dose of 0.5 g showed neither irritant nor corrosive effects. ...

... Single dermal application of the test item L-Cysteine to rats at a dose of 2000 mg/kg body weight was associated with neither mortality nor signs of toxicity but signs of irritation. ...

Suitable extinguishing media: Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.

Advice for firefighters: Wear self-contained breathing apparatus for firefighting if necessary.

ACCIDENTAL RELEASE MEASURES: Personal precautions, protective equipment and emergency procedures: Use personal protective equipment. Avoid dust formation. Avoid breathing vapors, mist or gas. Avoid breathing dust. Environmental precautions: Do not let product enter drains. Methods and materials for containment and cleaning up: Pick up and arrange disposal without creating dust. Sweep up and shovel. Keep in suitable, closed containers for disposal.

SRP: Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in air, soil or water; effects on animal, aquatic and plant life; and conformance with environmental and public health regulations. If it is possible or reasonable use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination.

Product: Offer surplus and non-recyclable solutions to a licensed disposal company; Contaminated packaging: Dispose of as unused product.

ACCIDENTAL RELEASE MEASURES: Personal precautions, protective equipment and emergency procedures: Use personal protective equipment. Avoid dust formation. Avoid breathing vapors, mist or gas. Avoid breathing dust. Environmental precautions: Do not let product enter drains.

Precautions for safe handling: Further processing of solid materials may result in the formation of combustible dusts. The potential for combustible dust formation should be taken into consideration before additional processing occurs. Provide appropriate exhaust ventilation at places where dust is formed.

Appropriate engineering controls: Handle in accordance with good industrial hygiene and safety practice. Wash hands before breaks and at the end of workday.

Gloves must be inspected prior to use. Use proper glove removal technique (without touching glove's outer surface) to avoid skin contact with this product. Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. Wash and dry hands.

SRP: Local exhaust ventilation should be applied wherever there is an incidence of point source emissions or dispersion of regulated contaminants in the work area. Ventilation control of the contaminant as close to its point of generation is both the most economical and safest method to minimize personnel exposure to airborne contaminants. Ensure that the local ventilation moves the contaminant away from the worker.

Residues of cysteine are exempted from the requirement of a tolerance when used in accordance with good agricultural practice as inert (or occasionally active) ingredients in pesticide formulations applied to growing crops only. Use: Synergist. Limit: Maximum of 0.5% of formulation.

Eye/face protection: Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).

Skin protection: Handle with gloves.

Body Protection: Choose body protection in relation to its type, to the concentration and amount of dangerous substances, and to the specific work-place. The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.

Respiratory protection: Respiratory protection is not required. Where protection from nuisance levels of dusts are desired, use type N95 (US) or type P1 (EN 143) dust masks. Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).

LD50; Species: Oncorhynchus mykiss (Rainbow trout) weight 30 g; Conditions: freshwater, 15 °C, ip injection; Concentration: 4.5 mmol/kg bw for 4 hr (95% confidence interval: 3.7-5.3 mmol/kg bw) /formulation/

LD50; Species: Oncorhynchus mykiss (Rainbow trout) weight 30 g; Conditions: freshwater, 15 °C, ip injection; Concentration: 4.8 mmol/kg bw for 3 hr (95% confidence interval: 4.5-5.7 mmol/kg bw) /formulation/

LD50; Species: Oncorhynchus mykiss (Rainbow trout) weight 30 g; Conditions: freshwater, 15 °C, ip injection; Concentration: 7.5 mmol/kg bw for 2 hr (95% confidence interval: 6.3-9.6 mmol/kg bw) /formulation/

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 3(SRC), determined from a structure estimation method(2), indicates that cysteine is expected to have very high mobility in soil(SRC). The pKa values of cysteine are 1.71, 8.33 and 10.78(3), indicating that this compound will exist as a zwitterion in the environment and zwitterions generally adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts(4). Volatilization from moist soil is not expected because the compound exists as an ion and ions do not volatilize. Cysteine is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 6.7X10-7 mm Hg at 25 °C(SRC), determined from a fragment constant method(2). Utilizing the Warburg test, 4.7% of the Theoretical BOD was reached in 24 hours(5) indicating that biodegradation is not an important environmental fate process in soil(SRC).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 3(SRC), determined from a structure estimation method(2), indicates that cysteine is not expected to adsorb to suspended solids and sediment(SRC). The pKa values of 1.71, 8.33 and 10.78(3) indicates cysteine will exist as a zwitterion at pH values of 5 to 9 and, therefore, volatilization from water surfaces is not expected to be an important fate process(SRC). According to a classification scheme(4), an estimated BCF of 3(SRC), from its log Kow of -2.49(5) and a regression-derived equation(2), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Utilizing the Warburg test, 4.7% of the Theoretical BOD was reached in 24 hours(6) indicating that biodegradation is not an important environmental fate process in water(SRC).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), cysteine, which has an estimated vapor pressure of 6.7X10-7 mm Hg at 25 °C(SRC), determined from a fragment constant method(2), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase cysteine is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 1.6 hours(SRC), calculated from its rate constant of 8.0X10-11 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Particulate-phase cysteine may be removed from the air by wet and dry deposition(SRC). Cysteine does not contain chromophores that absorb at wavelengths >290 nm(4) and, therefore, is not expected to be susceptible to direct photolysis by sunlight(SRC).

Safe in the present practices of use and concentration. Ingredient, concentration, and use information are available in documents discoverable at https://cir-reports.cir-safety.org

IDENTIFICATION AND USE: Cysteine forms white or colorless crystals. It is used in biochemical and nutrition research, as a reducing agent in bread doughs (up to 90 ppm). It is also used as flavor enhancer and medication, including veterinary medication. HUMAN EXPOSURE AND TOXICITY: Cysteine solution (3%) was not irritating for human eyes. ANIMAL STUDIES: A single ocular application of L-cysteine to rabbits at a dose of 0.1 g produced slight irritant effects, which were fully reversible within 48 hours. The single dermal application of L-cysteine to three rabbits at a dose of 0.5 g showed neither irritant nor corrosive effects. Decreased litter size observed in rats receiving high-dose cysteine, which was related to the degeneration and/or death of ovulated unfertilized oocytes and embryos with changes in the zona pellucida, which was already affected in the ovary. Pregnant mice and rats were treated s.c. with 1.2 mg per g on the last day of pregnancy and brain degeneration was observed one day later in the fetus. L-Cysteine is considered to be non-mutagenic in the HPRT locus using V79 cells of the Chinese Hamster. L-Cysteine did not induce structural chromosomal aberrations in the V79 Chinese hamster cell line. ECOTOXICITY STUDIES: The objective of the study was to determine the effects of cysteine on postthaw sperm motility, duration of sperm motility, DNA damage, and fertility in the common carp (Cyprinus carpio). Supplementation with cysteine increased the fertilization and hatching rate and decreased DNA damage.

Uremic toxins such as cysteine are actively transported into the kidneys via organic ion transporters (especially OAT3). Increased levels of uremic toxins can stimulate the production of reactive oxygen species. This seems to be mediated by the direct binding or inhibition by uremic toxins of the enzyme NADPH oxidase (especially NOX4 which is abundant in the kidneys and heart) (A7868). Reactive oxygen species can induce several different DNA methyltransferases (DNMTs) which are involved in the silencing of a protein known as KLOTHO. KLOTHO has been identified as having important roles in anti-aging, mineral metabolism, and vitamin D metabolism. A number of studies have indicated that KLOTHO mRNA and protein levels are reduced during acute or chronic kidney diseases in response to high local levels of reactive oxygen species (A7869). Although 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 usually be synthesized by the human body under normal physiological conditions if a sufficient quantity of methionine is available. Due to the ability of thiols to undergo redox reactions, cysteine has antioxidant properties. Cysteine's antioxidant properties are typically expressed in the tripeptide glutathione, which occurs in humans as well as other organisms. The systemic availability of oral glutathione (GSH) is negligible; so it must be biosynthesized from its constituent amino acids, cysteine, glycine, and glutamic acid. Glutamic acid and glycine are readily available in the diets of most industrialized countries, but the availability of cysteine can be the limiting substrate. Cysteine is also an important source of sulfide in human metabolism. The sulfide in iron-sulfur clusters and in nitrogenase is extracted from cysteine, which is converted to alanine in the process. In a 1994 report released by five top cigarette companie

As a uremic toxin, this compound can cause uremic syndrome. Uremic syndrome may affect any part of the body and can cause nausea, vomiting, loss of appetite, and weight loss. It can also cause changes in mental status, such as confusion, reduced awareness, agitation, psychosis, seizures, and coma. Abnormal bleeding, such as bleeding spontaneously or profusely from a very minor injury can also occur. Heart problems, such as an irregular heartbeat, inflammation in the sac that surrounds the heart (pericarditis), and increased pressure on the heart can be seen in patients with uremic syndrome. Shortness of breath from fluid buildup in the space between the lungs and the chest wall (pleural effusion) can also be present.

Using a structure estimation method based on molecular connectivity indices(1), the Koc of cysteine can be estimated to be 3(SRC). According to a classification scheme(2), this estimated Koc value suggests that cysteine is expected to have very high mobility in soil. The pKa values of cysteine are 1.71, 8.33 and 10.78(3) indicating that this compound will exist as a zwitterion in the environment and zwitterions generally adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts(4).

Chemical: L-Cysteine

Regulation (EC) No 1831/2003 (amended)

Reg. (EU) 2020/642

Status: Active Update: 10-11-2020 https://echa.europa.eu/registration-dossier/-/registered-dossier/12475；Status: Active Update: 30-01-2019 https://echa.europa.eu/registration-dossier/-/registered-dossier/23057

Cysteine: Does not have an individual approval but may be used under an appropriate group standard

Cysteine used as a nutrient and/or dietary supplement in animal drugs, feeds, and related products is generally recognized as safe when used in accordance with good manufacturing or feeding practice.

Substance added directly to human food affirmed as generally recognized as safe (GRAS).

The food additive amino acids may be safely used as nutrients added to foods in accordance with the following conditions: (a) The food additive consists of one or more of the following individual amino acids in the free, hydrated, or anhydrous form, or as the hydrochloride, sodium, or potassium salts. L-Cysteine is included on this list.

Residues of cysteine are exempted from the requirement of a tolerance when used in accordance with good agricultural practice as inert (or occasionally active) ingredients in pesticide formulations applied to growing crops only. Use: Synergist. Limit: Maximum of 0.5% of formulation.

L-Cysteine is the central compound in sulfur metabolism in the human body. In proteins the formation of disulfide bonds between the thiol groups of cysteine plays an important role for tertiary structure and enzymatic activity ... .

Amino acid catabolism is essential for adjusting pool sizes of free amino acids and takes part in energy production as well as nutrient remobilization. The carbon skeletons are generally converted to precursors or intermediates of the tricarboxylic acid cycle. In the case of cysteine, the reduced sulfur derived from the thiol group also has to be oxidized in order to prevent accumulation to toxic concentrations. ...

Due to this ability to undergo redox reactions, cysteine has antioxidant properties. 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 may at some point be recognized as an essential or conditionally essential amino acid.

Cysteine can usually be synthesized by the human body under normal physiological conditions if a sufficient quantity of methionine is available. Cysteine is typically synthesized in the human body when there is sufficient methionine available. Cysteine exhibits antioxidant properties and participates in redox reactions. Cysteine's antioxidant properties are typically expressed in the tripeptide glutathione, which occurs in humans as well as other organisms. Glutathione (GSH) typically requires biosynthesis from its constituent amino acids, cysteine, glycine, and glutamic acid, due to its limited systemic availability. Glutamic acid and glycine are readily available in the diets of most industrialized countries, but the availability of cysteine can be the limiting substrate. In human metabolism, cysteine is also involved in the generation of sulfide present in iron-sulfur clusters and nitrogenase by acting as a precursor. In a 1994 report released by five top cigarette companies, cysteine is one of the 599 additives to cigarettes. Its use or purpose, however, is unknown, like most cigarette additives. Its inclusion in cigarettes could offer two benefits: Acting as an expectorant, since smoking increases mucus production in the lungs; and increasing the beneficial antioxidant glutathione (which is diminished in smokers).

L-Cysteine is the central compound in sulfur metabolism in the human body. In proteins the formation of disulfide bonds between the thiol groups of cysteine plays an important role for tertiary structure and enzymatic activity; cysteine is however always incorporated in the polypeptide chain as cysteine. L-Cysteine is degraded to pyruvate in two steps: one is removal of sulfur and the other is a transamination. Cysteine can be metabolized to form taurine and carbon dioxide through the cysteinsulfinate pathway, where the initial step is oxidation of cysteine to cysteine sulfinate. This step is catalyzed by cysteine dioxygenase. Cysteine sulfinate may then be decarboxylated to form taurine or it may be metabolized via the putative intermediate beta-sulfinylpyruvate to pyruvate and sulfite and then to carbon dioxide and sulfate.

Amino acid catabolism is essential for adjusting pool sizes of free amino acids and takes part in energy production as well as nutrient remobilization. The carbon skeletons are generally converted to precursors or intermediates of the tricarboxylic acid cycle. In the case of cysteine, the reduced sulfur derived from the thiol group also has to be oxidized in order to prevent accumulation to toxic concentrations. Here we present a mitochondrial sulfur catabolic pathway catalyzing the complete oxidation of L-cysteine to pyruvate and thiosulfate. After transamination to 3-mercaptopyruvate the sulfhydryl group from L-cysteine is transferred to glutathione by sulfurtransferase 1 and oxidized to sulfite by the sulfur dioxygenase ETHE1. Sulfite is then converted to thiosulfate by addition of a second persulfide group by sulfurtransferase 1. This pathway is most relevant during early embryo development and for vegetative growth under light limiting conditions. Characterization of a double mutant produced from Arabidopsis thaliana T-DNA insertion lines for ETHE1 and sulfurtransferase 1 revealed that an intermediate of the ETHE1 dependent pathway, most likely a persulfide, interferes with amino acid catabolism and induces early senescence.

Uremic toxins tend to accumulate in the blood either through dietary excess or through poor filtration by the kidneys. Most uremic toxins are metabolic waste products and are normally excreted in the urine or feces.

2-Hydroxyglutric Aciduria (D And L Form)；3-Phosphoglycerate dehydrogenase deficiency；4-Hydroxybutyric Aciduria/Succinic Semialdehyde Dehydrogenase Deficiency；5-oxoprolinase deficiency；5-Oxoprolinuria；Amiloride Action Pathway；Bendroflumethiazide Action Pathway；Beta-mercaptolactate-cysteine disulfiduria；Blue diaper syndrome；Bumetanide Action Pathway；Total 65 pathways, visit the HMDB page for details

CIR ingredient: Cysteine

Cysteine is a non-essential amino acid that has been used as a dough conditioner and veterinary detoxicant; [Merck Index] Used as a flavoring agent, dough strengthener, nutritional supplement, and flour treating agent for foods; [FDA] Used for biochemical and nutritional research and as a medication; [HSDB]

Reported uses (ppm):；Table: Reported uses (ppm): (Flavor and Extract Manufacturers' Association, 1994) [Table#3867]

Biochemical and nutrition research, reducing agent in bread doughs (up to 90 ppm).

MEDICATION

MEDICATION (VET)

By addition of a thiol compound to an unsaturated amino acid derivative; by hydrolysis of proteins in the presence of carbon dioxide; by treating in HCl hydrolysis of proteins in the presence of carbon dioxide; by treating an HCl hydrolysate of hair with CuO2, followed by the decomposition of the resulting copper-cysteine complex with hydrogen sulfide; by the addition of thioacetic acid to alpha-acetamido acrylic acid; by treatment of a keratine HCl hydrolysate with zinc to reduce the cystine present to cysteine; by electrolytic reduction of cystine.

L-Cysteine used to be produced almost exclusively by hydrolysis of hair or other keratins. The amino acid isolated was l-cystine, which was reduced electrolytically to l-cysteine. L-Cysteine has also been prepared from beta-chloro-d,l-alanine and sodium sulfide with cysteine desulfhydrase, an enzyme obtained from, e.g., Citrobacterium freundii. Today, however, the main processes for cysteine production are biological. A direct fermentation process has been developed for the manufacture of l-cystine, using a modified Escherichia coli bacterium. The technology has been extended to prepare other modified l-cysteine analogues. An enzymatic process for l-cysteine has been successfully developed using microorganisms capable to hydrolyze 2-amino-delta2-thiazoline 4-carboxylic acid (ATC) which is readily available from methyl alpha-chloroacrylate and thiourea. A mutant of Pseudomonas thiazolinophilum converts d,l-ATC to l-cysteine in 95% molar yield at product concentrations higher than 30 g/L.

Flavouring Agent -> FLAVOURING_AGENT -> JECFA Functional Classes

Flavoring Agents -> JECFA Flavorings Index

Cosmetics -> Antistatic; Reducing; Antioxidant; Hair conditioning

L-Cysteine: ACTIVE

A non-essential amino acid in human development.

An amino acid derived from cystine, occurring naturally in the L-form ...