E920 (L-cysteine)

E920 (L-cysteine) = CYSTEINE

CAS Number: 52-90-4
EC Number: 200-158-2
MDL number: MFCD00064306
Linear Formula: HSCH2CH(NH2)CO2H
Molecular Formula: C3H7NO2S

E920 (L-cysteine) is an amino acid found naturally in the human body. 
E920 (L-cysteine) is one of the amino acids that are building blocks of the powerful antioxidant glutathione. 
E920 (L-cysteine) is found in many foods we eat. 
Pork chops, beef, chicken, and tuna are all good sources. 
So are oatmeal, eggs, and yogurt. 
Adding more to your diet through pills and powders may bring health benefits.

E920 (L-cysteine) (symbol Cys or C) is a semiessential proteinogenic amino acid with the formula HOOC-CH-(NH2)-CH2-SH. 
The thiol side chain in cysteine often participates in enzymatic reactions as a nucleophile. 
The thiol is susceptible to oxidation to give the disulfide derivative cystine, which serves an important structural role in many proteins. 
When used as a food additive, E920 (L-cysteine) has the E number E920. 
E920 (L-cysteine) is encoded by the codons UGU and UGC.

Like other amino acids (not as a residue of a protein), E920 (L-cysteine) exists as a zwitterion. 
E920 (L-cysteine) has l chirality in the older d/l notation based on homology to d- and l-glyceraldehyde. 
In the newer R/S system of designating chirality, based on the atomic numbers of atoms near the asymmetric carbon, E920 (L-cysteine) (and selenocysteine) have R chirality, because of the presence of sulfur (or selenium) as a second neighbor to the asymmetric carbon atom. 

The remaining chiral amino acids, having lighter atoms in that position, have S chirality. 
Replacing sulfur with selenium gives selenocysteine.
E920 (L-cysteine) is a proteingenic amino acid, which contributes toward a multitude of functions in biological systems. 
E920 (L-cysteine) is classified as a semiessential amino acid and can be synthesized in the liver from methionine, which is a sulfur-containing amino acid. 

This makes the abundance of methionine a critical factor to human health. 
As a building block, E920 (L-cysteine) contributes 2% of the total structural proteins in the body in the form of connective tissue, cell membranes, and the myelin sheaths around neurons, structures, which protect neurons from oxidative stress and harsh environmental conditions. 
The stiffness of the connective tissue neutralizes heavy metals in the body. 

E920 (L-cysteine) is a hydrophilic amino acid, possesses a thiol moiety which contributes toward its antioxidative properties, and has a high reactivity and affinity for heavy metals like mercury (Hg), leading to their excretion/detoxification from the body . 
E920 (L-cysteine) is given as a supplement in the form of precursor called N-acetyl-E920 (L-cysteine) (NAC). 
The body synthesizes glutathione (GSH) from cysteine; the former is a powerful antioxidant, toxin/radical scavenger. Glutathione (GHS) stimulates the production of leukotriene which is a key element in the body's defense system, inhibits inflammatory processes, and boosts the immune system. 

Dietary sources:
E920 (L-cysteine) is a residue in high-protein foods. 
Although classified as a nonessential amino acid, in rare cases, E920 (L-cysteine) may be essential for infants, the elderly, and individuals with certain metabolic diseases or who suffer from malabsorption syndromes. 
E920 (L-cysteine) can usually be synthesized by the human body under normal physiological conditions if a sufficient quantity of methionine is available.

Industrial sources:
The majority of E920 (L-cysteine) is obtained industrially by hydrolysis of animal materials, such as poultry feathers or hog hair. Despite widespread belief otherwise, little evidence shows that human hair is used as a source material and its use is explicitly banned for food additives and cosmetic products in the European Union. 
Synthetically produced E920 (L-cysteine), compliant with Jewish kosher and Muslim halal laws, is also available, albeit at a higher price. 

The synthetic route involves fermentation using a mutant of E. coli. 
Degussa introduced a route from substituted thiazolines. 
Following this technology, E920 (L-cysteine) is produced by the hydrolysis of racemic 2-amino-Δ2-thiazoline-4-carboxylic acid using Pseudomonas thiazolinophilum.

Biosynthesis:
In animals, biosynthesis begins with the amino acid serine. 
The sulfur is derived from methionine, which is converted to homocysteine through the intermediate S-adenosylmethionine. Cystathionine beta-synthase then combines homocysteine and serine to form the asymmetrical thioether cystathionine. 
The enzyme cystathionine gamma-lyase converts the cystathionine into E920 (L-cysteine) and alpha-ketobutyrate. 
In plants and bacteria, E920 (L-cysteine) biosynthesis also starts from serine, which is converted to O-acetylserine by the enzyme serine transacetylase. 
The enzyme E920 (L-cysteine) synthase, using sulfide sources, converts this ester into E920 (L-cysteine), releasing acetate.

Biological functions:
E920 (L-cysteine) sulfhydryl group is nucleophilic and easily oxidized. 
The reactivity is enhanced when the thiol is ionized, and E920 (L-cysteine) residues in proteins have pKa values close to neutrality, so are often in their reactive thiolate form in the cell. 
Because of E920 (L-cysteine)'s high reactivity, the sulfhydryl group of E920 (L-cysteine) has numerous biological functions.

Precursor to the antioxidant glutathione:
Due to the ability of thiols to undergo redox reactions, E920 (L-cysteine) and cysteinyl residues have antioxidant properties. 
E920 (L-cysteine)'s antioxidant properties are typically expressed in the tripeptide glutathione, which occurs in humans and other organisms. 

The systemic availability of oral glutathione (GSH) is negligible; so E920 (L-cysteine) must be biosynthesized from E920 (L-cysteine)'s constituent amino acids, cysteine, glycine, and glutamic acid. 
While glutamic acid is usually sufficient because amino acid nitrogen is recycled through glutamate as an intermediary, dietary E920 (L-cysteine) and glycine supplementation can improve synthesis of glutathione.

Precursor to iron-sulfur clusters:
E920 (L-cysteine) is 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.

Metal ion binding:
Beyond the iron-sulfur proteins, many other metal cofactors in enzymes are bound to the thiolate substituent of cysteinyl residues. 
Examples include zinc in zinc fingers and alcohol dehydrogenase, copper in the blue copper proteins, iron in cytochrome P450, and nickel in the [NiFe]-hydrogenases. 
The sulfhydryl group also has a high affinity for heavy metals, so that proteins containing cysteine, such as metallothionein, will bind metals such as mercury, lead, and cadmium tightly.

E920 (L-cysteine) is a sulfur-containing derivative obtained from oxidation of cysteine amino acid thiol side chains. 
E920 (L-cysteine) functions as an antioxidant and protects tissues against radiation and pollution, slowing the aging process. 
E920 (L-cysteine) also aids protein synthesis. 
E920 (L-cysteine) is abundant in many proteins of skeletal tissues and skin, and found in insulin and digestive enzymes chromotrypsinogen A, papain, and trypsinogen.

E920 (L-cysteine) is a non-essential amino acid important for making protein, and for other metabolic functions. 
E920 (L-cysteine)'s found in beta-keratin. 
This is the main protein in nails, skin, and hair. 
E920 (L-cysteine) is important for making collagen. 
E920 (L-cysteine) affects skin elasticity and texture. 
E920 (L-cysteine) has antioxidant properties.

E920 (L-cysteine) is an amino acid, a building block of proteins that are used throughout the body. 
When taken as a supplement, E920 (L-cysteine) is usually in the form of N-acetyl-E920 (L-cysteine) (NAC). 
The body makes this into E920 (L-cysteine) and then into glutathione, a powerful antioxidant.
E920 (L-cysteine) is an amino acid that serves as a building block of some proteins.  
E920 (L-cysteine) is one of the most common reducing agents in baking, as well as in enriched beef flavors.

A more sustainable fermentation process for producing vegan E920 (L-cysteine) and L-Cystine (a dimer of E920 (L-cysteine)) has been introduced. 
This uses plant-based raw materials such as corn and inorganic trace elements.
This method is more sustainable compared to the chemical extraction that uses large amounts of acid.

E920 (L-cysteine) is a semi-essential amino acid. 
E920 (L-cysteine) is abundant in many foods such as beef liver, crab cakes, lima beans and some mushrooms. 
E920 (L-cysteine) is also a component of many dietary supplements preparations.

E920 (L-cysteine) (Cys), also known as E920 (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. 
E920 (L-cysteine) is found in all organisms ranging from bacteria to plants to animals. 
E920 (L-cysteine) is classified as an aliphatic, non-polar, sulfur-containing amino acid. 
E920 (L-cysteine) is an important source of sulfur in human metabolism, and although E920 (L-cysteine) is classified as a non-essential amino acid, E920 (L-cysteine) may be essential for infants, the elderly, and individuals with certain metabolic disease or who suffer from malabsorption syndromes. 

E920 (L-cysteine) can occasionally be considered as an essential or conditionally essential amino acid. 
E920 (L-cysteine) is unique amongst the twenty natural amino acids as E920 (L-cysteine) contains a thiol group.
Thiol groups can undergo oxidation/reduction (redox) reactions; when E920 (L-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. 
E920 (L-cysteine) is often involved in electron-transfer reactions, and help the enzyme catalyze E920 (L-cysteine)'s reaction. 
E920 (L-cysteine) is also part of the antioxidant glutathione. 
N-Acetyl-E920 (L-cysteine) (NAC) is a form of cysteine where an acetyl group is attached to E920 (L-cysteine)'s nitrogen atom and is sold as a dietary supplement. 

E920 (L-cysteine) is named after cystine, which comes from the Greek word kustis meaning bladder (cystine was first isolated from kidney stones). 
Oxidation of E920 (L-cysteine) can produce a disulfide bond with another thiol and further oxidation can produce sulphfinic or sulfonic acids. 

E920 (L-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 E920 (L-cysteine) will bind metals such as mercury, lead, and cadmium tightly. 

Due to this ability to undergo redox reactions, E920 (L-cysteine) has antioxidant properties. 
E920 (L-cysteine) is important in energy metabolism. 
E920 (L-cysteine) is a structural component of many tissues and hormones. 
E920 (L-cysteine) has clinical uses ranging from treating baldness to psoriasis to preventing smoker's hack. 

In some cases, oral E920 (L-cysteine) therapy has proved excellent for treatment of asthmatics, enabling them to stop theophylline and other medications. 
E920 (L-cysteine) also enhances the effect of topically applied silver, tin, and zinc salts in preventing dental cavities. 
In the future, E920 (L-cysteine) may play a role in the treatment of cobalt toxicity, diabetes, psychosis, cancer, and seizures 
E920 (L-cysteine) is one of the two proteinogenic amino acids that contain a sulfur atom (the other is methionine). 

E920 (L-cysteine) is considered a nonessential amino acid because E920 (L-cysteine) is produced in the human body. 
Individuals who are deficient in cysteine, however, must be treated with supplements.
When E920 (L-cysteine) is oxidized, the two thiol hydrogen atoms are eliminated, and the sulfur atoms join to form the dimer L-cystine. 
In biological systems, the monomer and dimer interchange easily; thus, both acids are nutritionally similar.

E920 (L-cysteine) is a high quality research product used as multipurpose amino acid for protein synthesis, reagent stabilization, preparation of culture media and more. 
E920 (L-cysteine) is classified as a “semi-essential” amino acid because it can be made in small amounts by the human body, but many people can still benefit from consuming more cysteine from their diets or supplements because of its numerous health benefits. 

The human body can usually manufacturer E920 (L-cysteine) from the amino acids serine and methionine, but you need enough folate, vitamin B6 and vitamin B12 for that to be possible.
Along with two other amino acids, glutamine and glycine, E920 (L-cysteine) is needed to make glutathione, the master antioxidant that’s crucial for your health. 
E920 (L-cysteine) is usually the amino acid that’s in shortest supply for making glutamine, so E920 (L-cysteine)’s important that you get enough of this amino acid, even though E920 (L-cysteine)’s not considered essential.

Although E920 (L-cysteine) is a minor scavenger of oxidative stress, E920 (L-cysteine)'s most important role is reviving glutathione, one of the most powerful antioxidants in the body. 
Longevity researchers believe that glutathione is so pivotal to your health that the level of this antioxidant in your cells may be a predictor for how long you will live. 
E920 (L-cysteine)’s the body’s most important antioxidant because E920 (L-cysteine) is within the cell, making E920 (L-cysteine) essential for maintaining a healthy immune system and fighting cellular damage. 

E920 (L-cysteine) is used therapeutically and nutritionally to improve the health of humans. 
E920 (L-cysteine)’s a basic building block of glutathione, which has been coined “the mother of all antioxidants.” 
E920 (L-cysteine) supplementation, also known as N-acetyl-E920 (L-cysteine) (NAC), is valued for E920 (L-cysteine)'s ability to increase glutathione levels in the body, which is extremely important for lung function, brain function and liver detoxification. 
Because a number of health conditions deplete your glutathione levels, you need E920 (L-cysteine) to make more within your brain and body tissues.

E920 (L-cysteine) is also valued for E920 (L-cysteine)'s ability to break up mucus, thereby making E920 (L-cysteine) easier to cough up phlegm that’s caused by respiratory and pulmonary conditions. 
Plus, E920 (L-cysteine) is involved in regulating glutamate levels, influencing the neurons in the central nervous system. 
All need enough E920 (L-cysteine) in order to properly fight oxidative stress and conditions affecting the brain and lungs. 
E920 (L-cysteine) is made in small amounts by the human body, and you can also get E920 (L-cysteine) from high-protein foods and supplementation.

E920 (L-cysteine) and its oxidized form L-Cystine are essential amino acids used in cell culture and are present in all chemically defined media formulations. 
Both forms can be taken up by most cell lines, including those used in monoclonal antibody production. 
E920 (L-cysteine) is not only an important building block of biomass and recombinant proteins but also has a range of additional functions. 

For example, E920 (L-cysteine) is the rate limiting substrate in the biosynthesis of glutathione, which is the main mediator of intracellular redox homeostasis and helps to reduce oxidative stress. 
Thus, providing sufficient Cys-equivalents is critical to achieve the best bioprocess performance during the cultivation of cells in serum-free, chemically defined conditions.

E920 (L-cysteine) is a basic building block of the the antioxidant glutathione, the human body's most important antioxidant. Glutathione recharges vitamins C and E as they are used as antioxidants. 
E920 (L-cysteine) helps protect DNA from chemical damage. 
E920 (L-cysteine) detoxifies heavy metals, and it helps keep arteries and airways open. 
E920 (L-cysteine) also activates many important functions of the immune system.

E920 (L-cysteine) is also the amino acid every cell uses to make inteins, the enzymes that "snip" protein molecules to the right size and configuration, and the caspases, which dissolve dead cells, especially dead cancer cells, from the inside out.
E920 (L-cysteine) is not an "essential" amino acid. 
Under optimal conditions, the human body can manufacturer E920 (L-cysteine) from the amino acids serine and methionine. 
If the folic acid, vitamin B6, and vitamin B12 are not available, however, the body cannot make the enzymes that complete the conversion of serine and methionine into E920 (L-cysteine).

Once the body has made E920 (L-cysteine) from serine and methionine or digested E920 (L-cysteine) from food or supplements, E920 (L-cysteine) uses E920 (L-cysteine) along with two more amino acids, glutamine and glycine, to make the "master antioxidant" glutathione. 
There are some foods that contain glutathione, and E920 (L-cysteine) is possible to find a glutathione supplement, but so little of the antioxidant survives the digestion process that the body has to make essentially all of E920 (L-cysteine)'s own glutathione. 
Cysteine is usually the amino acid in shortest supply for making this antioxidant.

NAC is a precursor to E920 (L-cysteine) which is vital in replenishing levels of glutathione, an incredibly important antioxidant. E920 (L-cysteine) is available through foods like animal proteins and legumes, but there are differences between the two amino acids. 
NAC independently is also an antioxidant.
E920 (L-cysteine) is found in many foods we eat. Pork chops, beef, chicken, and tuna are all good sources. 
So are oatmeal, eggs, and yogurt.

USES and APPLICATIONS of E920 (L-cysteine):
-E920 (L-cysteine) also is found in many protein-rich foods and sold as a dietary supplement.
-E920 (L-cysteine) may help ease flu symptoms, treat some inflammatory diseases, and help diabetics to manage their illness.
-E920 (L-cysteine) may be used as a natural treatment for conditions that include:
Angina
Chronic bronchitis
Diabetes
Flu
Inflammatory bowel disease
Osteoarthritis

-E920 (L-cysteine) also may support lung health in people with chronic obstructive pulmonary disease (COPD), help prevent colon cancer, and boost sports performance in athletes.
-Diabetes:
Research suggests that E920 (L-cysteine) may help with diabetes management because E920 (L-cysteine) lowers blood sugar, reduces insulin resistance, and reduces blood vessel damage. 
This may be especially important for people who have heart disease or a genetic enzyme deficiency seen more often in men. E920 (L-cysteine)'s called G6PD for short and linked to many complications.

-E920 (L-cysteine) helps to offset G6PD deficiency.
High blood sugar counts can contribute to low G6PD levels and related blood and blood vessel problems, but E920 (L-cysteine) appears to restore those levels and improve function.

-Free Radicals:
E920 (L-cysteine) may help prevent the exercise-related production of free radicals, which are shown to contribute to oxidative stress and damage cells. 
The amino acid acts as an antioxidant.

-Studies have revealed that NAC can be helpful in treating many health problems like osteoporosis, acute respiratory diseases, and acetaminophen poisoning.
-E920 (L-cysteine), mainly the l-enantiomer, is a precursor in the food, pharmaceutical, and personal-care industries. 
One of the largest applications is the production of flavors. 
For example, the reaction of E920 (L-cysteine) with sugars in a Maillard reaction yields meat flavors. 
E920 (L-cysteine) is also used as a processing aid for baking.

-In the field of personal care, E920 (L-cysteine) is used for permanent-wave applications, predominantly in Asia. 
Again, the E920 (L-cysteine) is used for breaking up the disulfide bonds in the hair's keratin.
-E920 (L-cysteine) is a very popular target for site-directed labeling experiments to investigate biomolecular structure and dynamics. 
Maleimides selectively attach to E920 (L-cysteine) using a covalent Michael addition. 
Site-directed spin labeling for EPR or paramagnetic relaxation-enhanced NMR also uses E920 (L-cysteine) extensively.

-N-acetyl cysteine (NAC) comes from the amino acid E920 (L-cysteine). 
Amino acids are building blocks of proteins. 
N-acetyl cysteine is an antioxidant that might play a role in preventing cancer. 
As a drug, N-acetyl cysteine's used by healthcare providers to treat acetaminophen (Tylenol) poisoning. 
N-acetyl cysteine works by binding the poisonous forms of acetaminophen that are formed in the liver.

-E920 (L-cysteine) is a semi-essential amino acid and substrate for cystathionine-β-synthase (CBS) in the central nervous system. 
NaHS, an H2S donor, significantly alleviated brain damage after subarachnoid hemorrhage (SAH) in rats. 
-Antioxidants fight free radicals, which are harmful compounds in the body that damage cell membranes and DNA. 
Researchers think free radicals play a role in aging as well as the development of a number of health problems, including heart disease and cancer.

-Foods rich in E920 (L-cysteine) have been known for their health benefits since the Middle Ages. 
Chicken macerates containing E920 (L-cysteine) were often used to treat asthma. 
Drugs based on derivatives are still used today for asthma and other chronic obstructive pulmonary diseases (COPD).
-While E920 (L-cysteine) can be derived from animal and even human sources such as goose and duck feathers, human hair, swine bristles, and hooves, there is also a well-established fermentation process using plant starch as raw material.

-In commercial baking, E920 (L-cysteine) offers many benefits:
*Gluten softening and dough relaxing
*Dough conditioning
*Reduced mixing and fermentation times
*Better dough consistency and easier handling
*Improved pan flow

-In dough, E920 (L-cysteine) acts as a reducing agent that helps break down gluten proteins. 
This dough softening effect is especially valuable in high-protein flours which often produce dense crumb and low volume products. 

In high-speed bread systems, E920 (L-cysteine) has the following benefits:
*Compensation for high-protein flours
*Shorter mixing times
*Lower dough temperature
*Less stressed dough

*Extensible dough that is more flexible for dividing and rounding
*Less wear and tear on equipment
*Better (pan) flow
*Improved tolerance and less toughening during proofing
*Uniform products
*Higher volume because of facilitated rising

-Incorporating reducing agents such as this one to baked goods is essential for products made with high extraction flours. 
As well as, those processed in one bowl such as bread making machines.
-Sorghum-containing baked goods may benefit from the addition of E920 (L-cysteine) addition to improve their viscoelastic properties, reduce firmness and improve their digestibility.
-When using high levels of this ingredient, there is the potential development of sulfurous taste and aroma.

-The traditional production process for E920 (L-cysteine) starts with boiling the raw material (feathers or hair) in concentrated hydrochloric acid and activated carbon. 
Then, this is followed by electrolysis. 
One of the drawbacks of this approach is the need for huge amounts of concentrated sulfuric acid and water. 
-As a reducing agent, E920 (L-cysteine) may help prevent exercise-induced overproduction of free radicals. 
This reduces oxidative stress.

-Pharmacodynamics:
Due to this ability to undergo redox reactions, E920 (L-cysteine) has antioxidant properties. 
E920 (L-cysteine) is an important source of sulfur in human metabolism, and although E920 (L-cysteine) is classified as a non-essential amino acid, E920 (L-cysteine) may be essential for infants, the elderly, and individuals with certain metabolic disease or who suffer from malabsorption syndromes. 
E920 (L-cysteine) may at some point be recognized as an essential or conditionally essential amino acid.

-E920 (L-cysteine) is an amino acid very susceptible to oxidation. 
When added at low concentrations to water, dissolved oxygen levels and ORP readings rapidly drop while keeping the pH circumneutral. 
Adding E920 (L-cysteine) makes water suitable to carry and protect anaerobic bioaugmentation cultures while subsurface conditions become suitable. 
This conditioned water can also be used to disperse electron donors. 
Instead of having a drawn-out, lengthy process that often requires filtration and pH adjustment, simply add 0.1% E920 (L-cysteine) to a batch of water before injecting.

-Has Antioxidant Properties:
*E920 (L-cysteine) works as a scavenger of free radicals that cause cellular damage through oxidative stress, and E920 (L-cysteine) improves antioxidant capacity through the preservation of glutathione. 
This is the most well-known E920 (L-cysteine) benefit because E920 (L-cysteine) can slow down the aging process and help prevent or treat a number of serious health conditions. 

*This also means that by boosting your levels of glutathione, E920 (L-cysteine) supports immune function. 
Research suggests that immunological functions in diseases that are associated with a cysteine and glutathione deficiency may be significantly enhanced and potentially restored by E920 (L-cysteine) supplementation. 

*There are studies involving HIV patients that show E920 (L-cysteine)’s ability to boost your immune system. 
One study conducted in Europe showed that a formulation including NAC, bovine colostrum, omega-3 fatty acids, and a combination of vitamins and minerals slowed down the decline of immune cells. 
Another study showed that by replenishing glutathione levels, E920 (L-cysteine) appears to have a beneficial impact on the immune function of people living with HIV. 

*Researchers concluded that NAC supplementation can contribute to the maintenance of good health and quality of life in postmenopausal women by decreasing the probability of immune system-related diseases (such as infection) as they age. 

-Promotes Detoxification:
*E920 (L-cysteine) can be used to help prevent side effects caused by drug reactions and toxic chemicals. 
E920 (L-cysteine) plays a pivotal role in the detoxification mechanisms in the body. 
Toxic metals have pro-oxidative effects, and they deplete glutathione levels, so E920 (L-cysteine) supplements help restore those levels so that you can properly detoxify toxins. 

*Because E920 (L-cysteine) helps the body to detoxify dangerous toxins and chemicals, E920 (L-cysteine)’s common for doctors to give intravenous NAC to people who are having an acetaminophen overdose in order to prevent or reduce liver and kidney damage. 

-Increases Male Fertility:
Because E920 (L-cysteine) is supplemented to alleviate glutathione depletion during oxidative stress, E920 (L-cysteine)’s effective as a treatment of impotence in men who may have poor semen quality, DNA damage and oxidative stress.

-Balances Blood Sugar Levels:
*E920 (L-cysteine) is beneficial in helping support the body’s natural ability to manage and regulate normal blood sugar levels. 
E920 (L-cysteine) supplementation significantly lowered blood levels of glucose and insulin resistance. 

-Supports Digestive Health:
E920 (L-cysteine) improves the body’s digestive capacity because of E920 (L-cysteine)'s ability to slow the aging process. 
As people age, digestive issues like low stomach acid and gastroenteritis become more prominent. 
This can be due to the presence of free radicals in the body.
Studies suggest that E920 (L-cysteine) supplementation can help reduce the symptoms of ulcerative colitis, an inflammatory bowel disease that causes long-lasting inflammation and sores in the digestive tract. 

-Relieves Symptoms of Respiratory Conditions:
NAC works as an expectorant, and E920 (L-cysteine) can be used to break down mucus in the body. 
E920 (L-cysteine) helps decrease the severity and frequency of wheezing and respiratory attacks by boosting glutathione and thinning mucus that builds up in the bronchial tubes. 
This can be helpful when you are suffering from allergy symptoms or you have a respiratory condition like bronchitis or chronic obstructive pulmonary disease (COPD).

-Helps Treat Psychiatric Disorders:
More and more research has recently suggested that the use of NAC in the treatment of psychiatric illnesses is promising. According to a review published in the Journal of Psychiatry and Neuroscience, many of the disorders that may be benefited from NAC have limited treatment options or suboptimal outcomes with current treatments. 
Studies suggest that NAC has potential as a treatment for addiction, including marijuana dependence, nicotine addiction, cocaine addiction and even pathological gambling.

-Preliminary studies also show that E920 (L-cysteine) may be used in preventing or treating the following conditions:
acne
angina (restricted blood flow to the heart)
asthma
emphysema
colon cancer
lung cancer

-Foods:
Many high-protein foods contain E920 (L-cysteine), although usually in small amounts. 
These foods include:
chicken
turkey
duck
pork
yogurt
cheese
eggs
sunflower seeds
legumes
oat bran

Your body manufacturers E920 (L-cysteine) from the amino acids serine and methionine, but for that to be possible, you need adequate amounts of folate, vitamin B6 and vitamin B12 foods. 
You can get these vitamins from beans (like chickpeas and pinto beans), lentils, spinach, avocado, bananas, wild-caught salmon and tuna, and liver.

-E920 (L-cysteine) is also frequently recommended for acne, with the explanation that E920 (L-cysteine) "helps vitamin B5 work better." 
Vitamin B5 is pantothenic acid, often marketed in skin care products as Panthene or Panthetine. 
Typically the Internet experts who recommend a combination of E920 (L-cysteine) and high-dose vitamin B5 for acne argue that since vitamin B5 is water soluble and any excess is quickly removed from the bloodstream by the kidneys, the only way to trick the kidneys is by taking a mega-dose of vitamin B5 to work with the E920 (L-cysteine).

-E920 (L-cysteine) helps the skin defend itself against sun damage. 
Together with selenium, vitamin C, and vitamin E, E920 (L-cysteine) helps skin cells form the enzymes that keep a gene called p53 active. 
This "watchdog" gene triggers a series of steps that cause a potentially cancerous cell to undergo a process called apoptosis, or "cell suicide." 
When p53 detects changes in skin DNA that could cause cancer, E920 (L-cysteine) shuts down the cell. 
E920 (L-cysteine) is also important for the formation of the caspases that dissolve the cell once it dies.

-E920 (L-cysteine) an amino acid used to prolong shelf-life in products such as commercial bread can be found in duck and chicken feathers and cow horns, but most that’s used in food comes from human hair. 
You can avoid E920 (L-cysteine) by buying fresh bread from a local baker, as E920 (L-cysteine) is not an additive in flour.
-Even E920 (L-cysteine) derived from hair or poultry feathers is technically vegetarian because E920 (L-cysteine) is not derived from edible meat, fish or poultry (including their byproducts). 
E920 (L-cysteine) derived from feathers is not vegan but E920 (L-cysteine) is vegetarian.

-A form of cysteine called E920 (L-cysteine) may help treat arthritis and hardening of the arteries. 
E920 (L-cysteine) may help treat certain lung diseases. 
These include bronchitis, emphysema, and tuberculosis. 
Cysteine may play a role in the normal growth rate of hair.

ALTERNATIVE PARENTS:    
L-alpha-amino acids 
Amino acids 
Monocarboxylic acids and derivatives 
Carboxylic acids 
Alkylthiols 
Organopnictogen compounds 
Organic oxides 
Monoalkylamines 
Hydrocarbon derivatives 
Carbonyl compounds 

SUBSTITUENTS:    
Cysteine or derivatives
Alpha-amino acid
L-alpha-amino acid
Amino acid
Alkylthiol
Carboxylic acid
Monocarboxylic acid or derivatives
Organic oxygen compound
Primary amine
Organosulfur compound
Organooxygen compound
Organonitrogen compound
Organic nitrogen compound
Primary aliphatic amine
Carbonyl group
Amine
Hydrocarbon derivative
Organopnictogen compound
Organic oxide
Aliphatic acyclic compound

UNDERSTANDING SOLUBILITY CHALLENGES AND PERFORMANCE OF E920 (L-cysteine):
While the solubility of free E920 (L-cysteine) is high at a neutral pH, the applicable concentration in basal and feed media can be limited by several factors. 
The main challenge relates to E920 (L-cysteine)'s rapid oxidization to L-Cystine. 
This reaction is catalyzed by the presence of trace elements such as copper and iron which are typically present in cell culture media. 
E920 (L-cysteine) has a low solubility and can precipitate at concentrations which are higher than 1 mM. 

HOW DO YOU DISSOLVE E920 (L-cysteine)?
However, to prevent the oxidation, suggest you to dissolve the E920 (L-cysteine) in double distilled water with pH slightly acid (6.5) and/or degassing the water with N2 to reduce the oxygen concentration.

ARE AMINO ACIDS SOLUBLE IN DMSO?
Amino acid solubility measurements showed that the interactions between glycine and DMSO are highly unfavorable, while the interactions of DMSO with aromatic and hydrophobic side chains are favorable.

IS CYSTEINE SOLUBLE IN WATER?
Water
Acetic acid
Cysteine/Soluble in

WHAT IS THE SOLUBILITY of E920 (L-cysteine)?
Probably your cysteine is oxidazed to cystine which is insoluble in water. 
E920 (L-cysteine) is a thiol sensible to oxidation and undergoing to disulfide bond formation to produce cystine in the presence of oxidants like molecular oxygen.

WHAT IS E920 (L-cysteine) SOLUBLE?
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). 
E920 (L-cysteine) is the oxidized dimer form of the amino acid cysteine and has the formula (SCH2CH(NH2)CO2H)2. 
E920 (L-cysteine) is a white solid that is slightly soluble in water.

HOW DO YOU INCREASE THE SOLUBILITY of AN AMINO ACID?
The increase in total solubility of the amino acids is directly proportional to the number of moles of acid or base added. 
As the nonpolar portion of the amino acid molecule increased, the total resultant solubility per mole of acid or base added also increased.

E920 (L-cysteine) SUPPLEMENTS
N-acetyl-E920 (L-cysteine), also known as NAC, is the form of E920 (L-cysteine) found in nutritional supplements. 
Pure E920 (L-cysteine) is oxidized to another chemical called cystine if is stored on the shelf. 
The NAC form of E920 (L-cysteine) is not damaged by contact with the air, and releases E920 (L-cysteine) after digestion.

ROLES IN PROTEIN STRUCTURE OF E920 (L-cysteine):
In the translation of messenger RNA molecules to produce polypeptides, E920 (L-cysteine) is coded for by the UGU and UGC codons.
E920 (L-cysteine) has traditionally been considered to be a hydrophilic amino acid, based largely on the chemical parallel between E920 (L-cysteine)'s sulfhydryl group and the hydroxyl groups in the side chains of other polar amino acids. 
However, E920 (L-cysteine) side chain has been shown to stabilize hydrophobic interactions in micelles to a greater degree than the side chain in the nonpolar amino acid glycine and the polar amino acid serine. 

In a statistical analysis of the frequency with which amino acids appear in different chemical environments in the structures of proteins, free E920 (L-cysteine) residues were found to associate with hydrophobic regions of proteins. 
Their hydrophobic tendency was equivalent to that of known nonpolar amino acids such as methionine and tyrosine (tyrosine is polar aromatic but also hydrophobic), those of which were much greater than that of known polar amino acids such as serine and threonine.
Hydrophobicity scales, which rank amino acids from most hydrophobic to most hydrophilic, consistently place E920 (L-cysteine) towards the hydrophobic end of the spectrum, even when they are based on methods that are not influenced by the tendency of E920 (L-cysteine)s to form disulfide bonds in proteins. 

Therefore, E920 (L-cysteine) is now often grouped among the hydrophobic amino acids, though E920 (L-cysteine) is sometimes also classified as slightly polar, or polar.
While free E920 (L-cysteine) residues do occur in proteins, most are covalently bonded to other E920 (L-cysteine) residues to form disulfide bonds, which play an important role in the folding and stability of some proteins, usually proteins secreted to the extracellular medium. 
Since most cellular compartments are reducing environments, disulfide bonds are generally unstable in the cytosol with some exceptions as noted below.

Disulfide bonds in proteins are formed by oxidation of the sulfhydryl group of E920 (L-cysteine) residues. 
The other sulfur-containing amino acid, methionine, cannot form disulfide bonds. 
More aggressive oxidants convert E920 (L-cysteine) to the corresponding sulfinic acid and sulfonic acid. 
E920 (L-cysteine) residues play a valuable role by crosslinking proteins, which increases the rigidity of proteins and also functions to confer proteolytic resistance. 
Inside the cell, disulfide bridges between E920 (L-cysteine) residues within a polypeptide support the protein's tertiary structure. 

Insulin is an example of a protein with E920 (L-cysteine) crosslinking, wherein two separate peptide chains are connected by a pair of disulfide bonds.
Protein disulfide isomerases catalyze the proper formation of disulfide bonds; the cell transfers dehydroascorbic acid to the endoplasmic reticulum, which oxidizes the environment. 
In this environment, E920 (L-cysteine)s are, in general, oxidized to cystine and are no longer functional as a nucleophiles.
Aside from its oxidation to cystine, E920 (L-cysteine) participates in numerous post-translational modifications. 

The nucleophilic sulfhydryl group allows E920 (L-cysteine) to conjugate to other groups, e.g., in prenylation. 
Ubiquitin ligases transfer ubiquitin to E920 (L-cysteine)'s pendant, proteins, and caspases, which engage in proteolysis in the apoptotic cycle. 
Inteins often function with the help of a catalytic E920 (L-cysteine).
These roles are typically limited to the intracellular milieu, where the environment is reducing, and E920 (L-cysteine) is not oxidized to cystine.

PHYSICAL and CHEMICAL PROPERTIES of E920 (L-cysteine):
Molecular Weight: 121.16
Appearance Form: solid
Odour: No data available
Odour Threshold: No data available
pH: No data available
Melting point/freezing point:
Melting point/range: 240 °C - dec.

Initial boiling point and boiling range: No data available
Flash point: No data available
Evaporation rate: No data available
Flammability (solid, gas): The product is not flammable. - Flammability (solids)
Upper/lower flammability or explosive limits: No data available
Vapour pressure: No data available
Vapour density: No data available
Relative density: No data available

Water solubility: soluble
Partition coefficient: n-octanol/water
log Pow: -3,05 - Bioaccumulation is not expected., (ECHA)
Auto-ignition temperature: 292 °C - Relative self-ignition temperature for solids
Decomposition temperature: > 203 °C -
Viscosity: No data available
Explosive properties: No data available
Oxidizing properties: No data available

Other safety information
No data available
Min. Purity Spec:    99%
Spectra: LCMS, FT-IR, HPLC, Polarimetry
Physical Form (at 20°C): White crystalline powder
Melting Point: 220°C
Optical Rotation: +8.75° (c=12, 2N HCl)
Long-Term Storage: Store long-term in a cool, dry place
Average mass: 121.158 Da
Monoisotopic mass: 121.019745 Da

FIRST AID MEASURES of E920 (L-cysteine):
-General Information: 
Immediately remove any clothing contaminated by the product. 
Consult a physician and show this safety data sheet.
-Description of first aid measures:

*If inhaled:
Move person to fresh air. 
If not breathing, give artificial respiration. 
If breathing is difficult, give oxygen. 
Obtain medical aid.
If breathed in, move person into fresh air. 
If not breathing, give artificial respiration.

*In case of skin contact:
Immediately flush skin with running water for at least 15 minutes while removing contaminated clothing and shoes. 
Wash clothing before reuse. 
Obtain medical aid immediately.
Wash off with soap and plenty of water.

*In case of eye contact:
Immediately flush open eyes with running water for at least 15 minutes. 
Obtain medical aid immediately
Flush eyes with water as a precaution.

*If swallowed:
Do NOT induce vomiting without medical advice. 
Rinse mouth with water. 
Never administer anything by mouth to an unconscious person. 
Obtain medical aid immediately. 
Rinse mouth with water.
-Most important symptoms and effects, both acute and delayed:
-Indication of any immediate medical attention and special treatment needed: No data available

ACCIDENTAL RELEASE MEASURES of E920 (L-cysteine):
-Personal precautions, protective equipment and emergency procedures:
Ensure adequate ventilation. 

-Environmental precautions:
Do not let product enter drains, other waterways, or soil.
Methods and materials for containment and cleaning up: 
Vacuum, sweep up, or absorb with inert material and place into a suitable disposal container.
Consult local regulations for disposal.
No special environmental precautions required.
-Methods and materials for containment and cleaning up:
Sweep up and shovel. 
Keep in suitable, closed containers for disposal.

FIRE FIGHTING MEASURES of E920 (L-cysteine):
-Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
-Further information:
No data available

EXPOSURE CONTROLS/PERSONAL PROTECTION of E920 (L-cysteine):
-Control parameters:
Components with workplace control parameters:
-Exposure controls:
--Appropriate engineering controls:
Avoid contact with skin, eyes, and clothing. 
Wash hands before breaks and immediately after handling the product. 
Facilities storing or utilizing this material should be equipped with an eyewash fountain. 
Use adequate general and local exhaust ventilation to keep airborne concentrations low.
General industrial hygiene practice.

--Personal protective equipment:
*Eye/face protection:
wear goggles with side protection. 
A face shield may be appropriate in some workplaces. 
Use eyewear tested and approved under appropriate government standards such as OSHA 29 CFR 1910.133 or EU EN166.
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. 
Wash and dry hands.
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0,11 mm
Break through time: 480 min
Splash contact:
Material: Nitrile rubber
Minimum layer thickness: 0,11 mm
Break through time: 480 min

*Body Protection:  
At the minimum, wear a laboratory coat and close-toed footwear.

*Hand Protection:
Wear gloves selected based on an evaluation of the possible hazards to hands and skin, the duration of use, the physical conditions of the workplace, and the chemical resistance and physical properties of the glove material.

*Respiratory protection:
Respiratory protection is not required. 
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
*Control of environmental exposure:
No special environmental precautions required.

HANDLING AND STORAGE of E920 (L-cysteine):
-Precautions for safe handling:
-Conditions for safe storage, including any incompatibilities
Keep container tightly closed in a dry and well-ventilated place. 
Store in cool place.

Precautions for safe handling: 
Wash hands thoroughly after handling.  
Wear suitable protective clothing, gloves, and eye/face protection.
Open and handle container with care. 
Do not eat, drink, or smoke while handling.

Conditions for safe storage, including any incompatibilities: 
Store in a tightly-closed container when not in use. 
Store long-term at room temperature.

STABILITY and REACTIVITY of E920 (L-cysteine):
-Reactivity: No data available
-Chemical stability: Stable under recommended storage conditions.
-Possibility of hazardous reactions: No data available
-Conditions to avoid: No data available
-Other decomposition products: No data available

SYNONYMS:
(R)-2-Amino-3-mercaptopropionic acid
(2R)-2-Amino-3-sulfanylpropanoic acid
L-2-Amino-3-mercaptopropionic acid
H-Cys-OH
a-amino-b-thiolpropionic acid
L-(+)-Cysteine
(+)-2-Amino-3-mercaptopropionic acid
(2R)-2-amino-3-mercaptopropanoic acid
(2R)-2-amino-3-sulfanylpropanoic acid
(2R)-2-Amino-3-sulfanylpropansäure [German]
(R)-(+)-Cysteine
(R)-2-amino-3-mercapto-Propanoic acid
(R)-2-Amino-3-mercaptopropionic acid
(R)-Cysteine
Cysteine, L-
β-Mercaptoalanine
Cystein
Cysteine
Half-cystine
L-(+)-Cysteine
L-Alanine, 3-mercapto-
Propanoic Acid, 2-amino-3-mercapto-, (R)-
Thioserine
(R)-2-Amino-3-mercaptopropanoic acid
α-Amino-β-thiolpropionic acid
(R)-Cysteine
2-Amino-3-mercaptopropionic acid
L-Cys
(2R)-2-Amino-3-mercaptopropanoic acid    
(2R)-2-Amino-3-sulfanylpropanoic acid    
(R)-2-Amino-3-mercaptopropanoic acid
(2R)-2-Amino-3-mercaptopropanoate    
(2R)-2-Amino-3-sulfanylpropanoate    
(2R)-2-Amino-3-sulphanylpropanoate    
(2R)-2-Amino-3-sulphanylpropanoic acid    
(R)-2-Amino-3-mercaptopropanoate    
L-2-Amino-3-mercaptopropionate    
(+)-2-Amino-3-mercaptopropionic acid    
(R)-(+)-Cysteine    
(R)-2-Amino-3-mercapto-propanoate    
(R)-2-Amino-3-mercapto-propanoic acid    
(R)-Cysteine    
2-Amino-3-mercaptopropanoate    
2-Amino-3-mercaptopropanoic acid    
2-Amino-3-mercaptopropionate    
2-Amino-3-mercaptopropionic acid    
3-Mercapto-L-alanine