Author: Site Editor Publish Time: 2020-04-13 Origin: Site
Cysteine (L-Cysteine) is a non-essential amino acid, but has a superb biochemical effect, its basic chemical composition includes amino, nitrogen, carbon, oxygen and hydrogen plus sulfur-containing thiol. "Mercapto" is a common antimicrobial agent of dimercury sodium thiosalicylate (trade name thimerosal Note 1), indicating that this compound contains sulfur and hydrogen atoms combined. Since the ancient Greeks applied garlic in medicine, elemental sulfur has been used to treat various diseases. Cysteine has higher quality sulfur than garlic, so many of the original sulfur applications were replaced by cysteine.
The cysteine sulfhydryl group is concentrated at the end of the cystine molecule. Mercapto compounds not only prevent the oxidation of sensitive tissues, but when it encounters aging and cancer cells, it first oxidizes with these cells to help the body clean up these harmful chemicals and carcinogens and protect the body. effect. Its derivatives N-acetylcysteine and glutathione are extremely powerful compounds.
Cysteine form and absorption
Studies have shown that the acetylated form of cysteine is the best form of absorption by the body. The forms of D-cystine and D-cysteine have toxic effects and are not suitable for human use.
Cysteine in the human body should be balanced with other amino acids. When the levels of phenylalanine and tryptophan in the body are high, you should be alert to the possibility of cysteine levels being reduced. When the level of cysteine decreases, the antioxidant capacity of the body will also decrease, which will lead to a decline in immunity and aging of the body. The levels of amino acids, vitamins, trace elements and fatty acids in the blood should be constantly measured and monitored by doctors to optimize the state of the body and meet the needs of the body.
Cysteine is derived from methionine, which is in the form of a double bond. It is a very unstable molecule and it is quickly converted to cystine. Cysteine, like all sulfur-containing amino acids, requires adequate pyridoxine (vitamin B6), cyanocobalamin (vitamin B12) and folic acid during the generation process. Cysteine can be converted from methionine to N-acetylcysteine (NAC), taurine, vitamin B1, coenzyme A, and many other organic sulfur molecules for cell needs.
In the process of cysteine conversion, high-dose vitamin B6 has a therapeutic effect on renal tumors, thyroid and galactosemia; if vitamin B6 is deficient, it can cause methionine to have an obstacle in the conversion of cysteine, which can cause Cystathionuria. If you do not correct vitamin B6 deficiency, it can also lead to mental retardation, thrombocytopenia, and imbalances in the body's pH levels.
The body's demand for cysteine
The National Academy of Sciences has not established a requirement for the daily intake of cysteine. Since both methionine and cysteine increase glutathione levels, daily intake of methionine and cysteine is required.
The minimum daily intake requirements for methionine and cysteine are 22 mg / kg per kg body weight for children and 10 mg / kg per kg body weight for adults. Some researchers believe that as long as 5 mg / kg of cysteine can meet daily needs, this is about 350 mg of cysteine every day; the minimum requirement is total sulfur-containing amino acids (taurine, cyste Methionine and methionine) can be as high as 1400 mg / day after investigation from the body. The World Health Organization (WHO) has established a preliminary requirement for sulfur-containing amino acids (mainly based on methionine). It requires a supplement of 13 mg / kg of sulfur-containing amino acids per kilogram of body weight per day, that is, an adult male of 70 kg. Supplementing 910 mg of sulfur-containing amino acids, this requirement also depends on gender, age, and diet.
Sources of cysteine in food
The best food sources of cysteine are eggs, meat, dairy products, cereals and beans. However, cysteine in food is present in the liquid of the food, so accurate cysteine levels in food are difficult to measure. However, the level of cystine in food can be accurately determined. Generally speaking, foods with high content of cystine are foods with high content of cysteine. Vegetarians often lack cysteine, which can lead to low protein and malnutrition.
The relationship between vitamins and cysteine
Cysteine and vitamin C are antioxidants of the body, protect cell membranes from the danger of lipid oxidation, and have detoxifying and sterilizing effects. Glutathione is an important component of the immune system; however, it has been found in animal experiments that, like rats, their bodies are different from our humans, they cannot synthesize vitamin C, and the amount of glutathione produced is also very large less.
Cysteine also has very important uses in other industries, such as the production of pesticides and herbicides in agriculture: it is widely used in plastic surgery and pharmaceutical production.
Cysteine side effects
When cysteine is not converted to L-cysteine, accumulation is harmful in the body, resulting in kidney dysfunction and kidney stones. This symptom often occurs in patients with an inherited cystine disease (or Fanconi's syndrome). Children with cystine disease often die of kidney failure around the age of ten. The accumulated thousands of tiny cystine crystals are embedded in many organs. The cystine level in the body is about 100 times the normal value. Although there is no way to remove cystine crystals. However, cysteine derivatives called cysteamine (also known as mercaptoethylamine-mercaptoethylamine) can quickly eliminate excessive L-cysteine in cells. Excessive L-cysteine can cause gastrointestinal ulcers, fever, rash, drowsiness, and lower neutrophil counts. (Neutral cytoplasm is the main component of leukemia, which causes cystine surplus. We think it is because clinicians are treating hair loss, or the lowest reduction of a type of bad cholesterol (very low density lipoproteins, very low density lipoprotein, In the process of VLDL), L-cystine was used.
In the reduction of harmful chemicals in the body or anti-oxidation treatment, the oxygen form of cystine to cysteine is usually better than the direct use of cysteine.
Dosage of cysteine and cystine
Both L-cysteine and L-cystine are forms that are not easily absorbed. Supplementing 6 grams of cystine will not increase the level of cystine in the blood. The oxidized form of cysteine can decompose protein, which will lead to an increase of hydroxylysines, which is a toxic form of lysine. Oral cystine has no significant effect on various biological parameters of the body. However, after acetylation of L-cysteine, N-acetyl-cysteine (N-acetyl-cysteine) is the best form of absorption.
The most effective method is to take acetylcysteine supplements orally to increase glutathione levels. Glutathione is a tri-peptide small molecule white matter, expensive, and oral glutathione is not economical and practical. Glutathione has a rapid effect and is often used in stressful and stressful situations, such as illness treatment, intense exercise, or excessive fatigue.
Improve the body's glutathione levels, and better provide raw materials for the body. The use of cysteine supplementation can also achieve the purpose of increasing glutathione levels in the body, but the effect of acetylcysteine supplementation is particularly optimal. Acetylcysteine is also a core antioxidant and is highly polluted for a long time. Food levels, people with smoking habits, patients with liver disease, and those whose body is beginning to age, should be taken daily with vitamin C, vitamin E, trace elements selenium, β-carotene, and lipoic acid to protect the body at the best Healthy state.
Symptoms of cysteine deficiency
There are no known symptoms due to cysteine deficiency.
The practicality of supplementing cysteine
Single cysteine 500 mg capsule; or acetylcysteine 600 mg capsule. Intravenous injection of acetylcysteine or glutathione can also be used.
The maximum safety limit of cysteine use
The maximum dosage is not specified. However, supplementation of cysteine and acetylcysteine is very safe even at high doses.
Cysteine's side effects and contraindications
In severe cases, the use of 7 grams of acetylcysteine has no significant side effects. The recommended limit of cysteine is 500 mg. If the daily use of cysteine is 1000 mg, it should be implemented under the supervision of a doctor. Large doses of cysteine can cause indigestion. At the same time, large doses of cysteine must be supplemented with large doses of vitamin C to prevent the conversion of cysteine to cystine and the formation of kidney stones.
The dosage of cysteine exceeds 7 grams, which may be harmful to the body. Cystinuria is a genetic disease. The urine secretes a large amount of cystine and other amino acids, which increases the risk of forming both cholinergic stones. Excessive cysteine can also cause liver damage. And even some symptoms of schizophrenia.
Summary of Cysteine
Cystine is a composition of many tissue structures and hormones. Cysteine plays a very important role in energy metabolism; cysteine is also a ubiquitous tripeptide small molecule protein --- the precursor of glutathione, so it will acetylcysteine Acids (chemical variants of cysteine), penicillamine (D-penicillamine), gamma-glutamyl (Y-glutamy), cystine and cysteamine become very active.
Glutathione plays many roles in the body. It is a coenzyme in promoting various enzyme reactions. The most important of these is the redox reaction. Cysteine sulfhydryl groups accumulate in the cell membrane to prevent peroxidation caused by the combination with oxygen. Glutathione (especially in the liver) can lock in toxic chemicals and detoxify them. Glutathione constitutes the body's immune system in red blood cells and white blood cells.