L-Methionine
L-Methionine
CAS: 63-68-3
Molecular Formula: C5H11NO2S
L-Methionine - Names and Identifiers
| Name | L-Methionine |
| Synonyms | L-Met-OH H-Met-OH Methionine L-Methionine METHYL-13CH3) L(-)-Methionin L-Methionine, USP Grade (L)-S-methylhomocysteine L-Methionine, Animal-Free L-METHIONINE (1,2,3,4-13C4 L-METHIONINE (13C5,D8,15N) 2-Methyl Eneghlutaronitrile (S)-2-Amino-4-(methylthio)butyric acid |
| CAS | 63-68-3 |
| EINECS | 200-562-9 |
| InChI | InChI=1/C5H11NO2S/c1-9-3-2-4(6)5(7)8/h4H,2-3,6H2,1H3,(H,7,8)/t4-/m0/s1 |
L-Methionine - Physico-chemical Properties
| Molecular Formula | C5H11NO2S |
| Molar Mass | 149.21 |
| Density | 1,34g/cm |
| Melting Point | 284°C (dec.)(lit.) |
| Boling Point | 393.91°C (estimate) |
| Specific Rotation(α) | 23.25 º (c=2, 6N HCl) |
| Water Solubility | Soluble |
| Solubility | Soluble in water, inorganic acid and hot dilute ethanol, solubility in water: 53.7G/L (20°C); Insoluble in absolute ethanol, ether, benzene, acetone and petroleum ether |
| Appearance | White crystal |
| Color | White |
| Maximum wavelength(λmax) | ['λ: 260 nm Amax: 0.40', , 'λ: 280 nm Amax: 0.05'] |
| Merck | 14,5975 |
| BRN | 1722294 |
| pKa | 2.13(at 25℃) |
| PH | 5-7 (10g/l, H2O, 20℃) |
| Storage Condition | 20-25°C |
| Stability | Stable. Incompatible with strong oxidizing agents. |
| Sensitive | Sensitive to light |
| Refractive Index | 1.5216 (estimate) |
| MDL | MFCD00063097 |
| Physical and Chemical Properties | Melting point 276-279°C (dec.) specific rotation 23.25 ° (c = 2, 6N HCl) water-soluble soluble |
| Use | For biochemical research and nutritional supplements, but also for Pneumonia, cirrhosis and fatty liver and other adjuvant therapy |
L-Methionine - Risk and Safety
| Risk Codes | 33 - Danger of cumulative effects |
| Safety Description | 24/25 - Avoid contact with skin and eyes. |
| WGK Germany | 2 |
| RTECS | PD0457000 |
| FLUKA BRAND F CODES | 10-23 |
| TSCA | Yes |
| HS Code | 29304010 |
| Toxicity | LD50 oral in rat: 36gm/kg |
L-Methionine - Nature
Open Data Verified Data
White flaky crystal or crystalline powder, with extra odor and slightly sweet taste. Unstable in case of strong acid. Soluble in water (3%,25 ° C), soluble in dilute acid and dilute alkali, ethanol-soluble, almost insoluble in ether.
Last Update：2025-06-10 22:55:16
L-Methionine - Preparation Method
Open Data Verified Data
obtained by the reaction of methyl mercaptan and acrolein.
Last Update：2022-01-01 09:27:39
L-Methionine - Application
Open Data Verified Data
for biochemical studies. It is used in the fields of chiral drugs, chiral additives, chiral auxiliaries and the like, and is used as a chiral source for Chiral synthesis in the pharmaceutical industry.
Last Update：2025-08-19 16:24:40
L-Methionine - Safety
Open Data Verified Data
- This product is non-toxic and can be used as a feed additive. But it is reported that a large number of intake of this product will cause Vomit, loss of appetite and other symptoms. In rats, I. P., Type L: LD50 29mmol/kg; Type D: LD50 35mmol/kg. Special attention should be paid to the use of highly toxic raw material sodium cyanide in the production process of methionine. Therefore, the production workshop should take corresponding measures according to the requirements of sodium cyanide toxicity protection: the equipment should be sealed, and the production site should be well ventilated, operators should wear protective equipment, etc.
- the use of plastic bags lined or kraft paper bag barrel packaging, should be stored in a cool and ventilated dry place. Storage and transportation should be closed, protected from light and moisture. According to the provisions of the general transport of chemicals.
Last Update：2022-01-01 10:37:54
L-Methionine - Reference Information
| NIST chemical information | information provided by: webbook.nist.gov (external link) |
| EPA chemical substance information | information provided by: ofmpeb.epa.gov (external link) |
| methionine | methionine is a sulfur-containing non-polar aliphatic amino acid, also known as methionine, which is one of the essential amino acids, abbreviated as Met, M. Glucogenic essential amino acids. Isolated from casein in 1922. It is the only amino acid with a thioether structure. There are l-and dl-bodies. Natural products are l-body. Relative molecular mass 149.21. Special odor. Slightly Sweet. Stable to air and heat. L-methionine can be obtained from many proteins by hydrolysis or fermentation. DL-methionine is synthesized by chemical method through the following reaction, and the relevant reaction equation is as follows: L-methionine is an amino acid necessary for the nutrition of human and animal body, and is commonly used in the preparation of compound amino acid infusion, or the treatment of acute hepatitis, cirrhosis of the liver disease drugs, as well as drug antidote. DL-methionine is widely used in the feed of cattle, pigs and broilers. its metabolism is associated with cysteine. In prokaryotes, formylated methionine is the starting amino acid for protein biosynthesis. It can also be activated by ATP into s-adenosylmethionine, as a methyl donor involved in the synthesis of creatine, choline. A lack of methionine does not allow normal growth and development of young rats. The main physiological function of methionine is the supply of methyl groups. It takes part in the biochemical reaction of methyl transfer in vivo by providing a methyl group (-CH3), which is required to supply methyl group in the synthesis of choline and creatine, lysine in some protein molecules, histidine and arginine are also required to provide methyl groups for methylation, and free carboxyl groups on protein molecules are also required to provide methyl groups for methylation. Methionine-rich foods to meat, fish, poultry, eggs, and beans and cereals mixed food can play a complementary role in protein. |
| feed additive | methionine is mainly used as a feed Nutrition Fortifier. Is one of the essential amino acids for animal growth, is the protein biosynthesis of the "skeleton" amino acids, the main donor of methyl groups in animals, it plays a role in the synthesis of choline and phospholipid of liver fat in the metabolism of adrenaline in animals. Lack of methionine in livestock and poultry will cause dysplasia, weight loss, liver and kidney function, muscle atrophy, hair deterioration and so on. methionine is a sulfur-containing amino acid, which is the second essential limiting amino acid in pigs. If the appropriate addition of lysine and methionine in feed, can effectively improve the utilization rate of feed protein, so lysine and methionine is known as protein feed fortifier. There are two types of naturally occurring methionine, D-type and L-type, and their bioavailability is identical. Synthetic methionine is a mixture of D-type and L-type DL-type compounds, biological potency and a single D-type or L-type methionine exactly the same. DL-type methionine additive appearance is white to light yellow crystal or crystalline powder, insoluble in water, slightly sweet. The amount of methionine in the pig formula feed is generally 0.05% to 0.1%. methionine is used as a nutritional supplement, l-form and dl-form have the same effect (because l-form is converted from dl-form); Feed additive; because this product and cystine are sulfur-containing amino acids, they are abundant in animal proteins, and in plant proteins, such as oats, rye, rice, corn, wheat, peanuts, soybeans, potatoes, plant foods such as spinach are limited amino acids, and the content is small, so it can be added to the food to improve the balance of amino acids. In the past, sulfur-containing amino acids were only suitable for non-ruminant animals, but now it is proved by experiments that sulfur-containing amino acids are also suitable for ruminant animals, more suitable for chicken and pig feed, and used as infusion together with other amino acids in medicine; it is also used as a medium for fermentation. |
| methionine and its metabolism | methionine is a sulfur-containing amino acid that constitutes a protein, has a non-polar side chain, and is anaerobic. methionine is a nutritionally essential amino acid, because methionine can only be synthesized in animals under certain conditions, therefore, the physiological value of a variety of plant proteins depends on the amount of methionine they contain. The physiological metabolic importance of methionine is as follows: ①methionine can be activated and converted into S-adenosylmethionine, which acts as a methyl donor and participates in the synthesis of methylation of many important nitrogen-containing compounds; (2) methionine is the most fundamental sulfur-containing compound in the body, which can be converted into important cysteine, providing SH groups of enzyme proteins, membrane proteins, etc. It can be seen that methionine has the function of transmethyl and sulfur transfer in metabolism. Homoserine in the liver "homoserine deaminase" catalyzed by the amino group to Alpha ketobutyrate. Alpha ketobutyric acid becomes propionyl-CoA by oxidative decarboxylation (refer to the "threonine and its metabolism" bar) and can continue to be converted into succinyl-CoA into the tricarboxylic acid cycle. |
| pharmacodynamics | methionine is a sulfur-containing amino acid. The synthesis of choline in the body needs to supply methyl by methionine, and Choline is a component of lecithin, lecithin is an indispensable material for the transport of fat out of the liver and the removal of fat deposition in the liver, therefore, methionine also has the effect of choline. In addition, methionine in the body to supply sulfur to synthesize non-exogenous amino acid amino acid, and the latter has a detoxification effect, so the drug is used in the clinical lipid and liver, suitable for fatty liver and chronic hepatitis with fatty infiltration, liver cirrhosis. Clinical methionine can also be used as alcohol, sulfa poisoning adjuvant therapy. |
| amino acids | amino acids are the constituent units of proteins and the material basis of life, ranging from humans to microbes, none consists of proteins. Proteins are composed of peptides, and peptide chains of peptides are composed of amino acids. Different proteins are composed of peptide chains with different sequences and lengths of amino acids. Genes associated with inheritance are actually also chains of amino acids in different sequences. at present, there are 28 kinds of amino acids related to human body. These 28 amino acids are arranged in different sequences and peptide chains of different lengths to make up the proteins of the various parts of the body. Of these 28 amino acids, 9 (about 32%) are directly supplied by the amino acids of dietary proteins, they cannot be synthesized in the human body from other amino acids in the proteins ingested. These are leucine, isoleucine, valine, lysine, methionine, tryptophan, threonine, phenylalanine and histidine. methionine is an essential amino acid. It can help break down fat, so it can prevent fatty liver, prevent heart, cerebrovascular disease and kidney disease. The synthesis of amino acids such as cystine and taurine requires the assistance of methionine. This amino acid helps remove harmful substances such as lead and other heavy metals. It can prevent muscle weakness, prevent hair embrittlement. It is also beneficial for the prevention and treatment of osteoporosis or chemical allergy. It is good for the treatment of rheumatic fever and toxemia in pregnancy. methionine is also a potent antioxidant. The sulfur it contains can scavenge free radicals. Methionine is required for the synthesis of nucleic acids, collagen and proteins in the body's cells. Methionine is also beneficial for women who take contraceptives. Because it can reduce the level of histamine in the body, it is effective in the treatment of schizophrenia, because the blood histamine level of schizophrenia patients is much higher than that of normal people. if there is an increase in toxic substances in the body, the need for methionine also increases. Because the body converts methionine into cystine, a precursor of glutathione, the major toxic neutralizer for the liver. This will protect the liver from toxic substances. methionine-rich foods include: Soy, other legumes, eggs, fish, garlic, meat, onions, and yogurt. |
| methionine production process flow diagram | The qualified propylene, air and water are fed into the reaction column in a certain proportion, the reaction is carried out in the presence of a catalyst, and the reactants are absorbed through an absorption column and then passed to a rectification column to be distilled to obtain product acrolein. acrolein and methyl mercaptan were fed into a MA synthesis Tower (I. E., a methylthiopropionaldehyde synthesis Tower) to be reacted, and the reactant was methylthiopropionaldehyde. Then the reaction product in the MA synthesis tower is passed into the MH synthesis Tower (I. E., β-methylthioethyl hydantoin), and then hydrocyanic acid (or sodium salt) and ammonium bicarbonate are added for reaction, followed by hydrolysis with sodium hydroxide, the methionine product was obtained by neutralization with sulfuric acid, vacuum distillation, crystallization and centrifugal drying. Reference: Wang daosu, editor-in-chief. Fine chemical production flow diagram, 1. Beijing: Chemical industry press. 1997 |
| toxicity | LD50 36g/kg (rat, oral). Safe for use in food (FDA § 172.320,2000). |
| usage limit | accounted for 3.1% of total protein in food (FDA172.230,2000). |
| Use | amino acid drugs and nutritional supplements. For liver cirrhosis and fatty liver. In addition, a large number of used as feed additives to improve feed quality, improve the utilization of natural protein and promote the development of animals. For example, DL-methionine can increase the egg production of chickens, increase the weight of pigs, and increase the milk production of cows. Adverse reaction: hepatic coma. nutritional supplements. One of the essential amino acids of the human body. Since the price is higher than DL-methionine and the effect is equal, DL-methionine is commonly used. nutritional supplements. One of the essential amino acids for human body. used in biochemical research and nutritional supplements, also used in Pneumonia, liver cirrhosis and fatty liver treatment |
| production method | It is obtained by resolving the optical rotation of acetyl-DL-methionine by amylase. technical route for dehydration process, glycerin, potassium hydrogen sulfate and potassium sulfate are added at a ratio of 1:0.5:0.026. Put 1/7 of the glycerin and all the potassium bisulfate and potassium sulfate to be administered into the reaction tank, raise the temperature to 190 ℃, then add the rest of the glycerin Dropwise, and control the reaction temperature to 180-220 ℃, the acrolein gas produced by the reaction is collected in a storage tank through a condenser to obtain a crude product of acrolein. The crude product was adjusted to pH 6 by adding 10% NaHCO3 solution, fractionated, and 50-75 °c fractions were collected to obtain a crude product of acrolein. The addition is fed according to the ratio of 1:2.45:3.8:0.01:0.024 of acrolein, methylisothiourea sulfate, sodium hydroxide, copper acetate and formic acid. After cyclization, put methylisothiourea sulfate into the methyl mercaptan generating tank, add NaOH solution Dropwise, and at the same time, heat to control the temperature not to exceed 95 ℃, and enter the generated methyl mercaptan into the buffer tank first, then it enters a washing tank containing 50% sulfuric acid solution and another stage of Flushing tank, and finally enters an addition tank into which acrolein, formic acid and copper acetate are put in advance, and is heated and stirred to maintain the reaction temperature at 35-41 °c. When the reaction was close to the end point, the reactants were pale yellow and mixed with floc, and the relative density was measured from time to time. When the relative density was 1.066-1.074 (20 °c), the end point of the reaction was reached. 3-methylthiopropionaldehyde was obtained. 3-methylthiopropionaldehyde, sodium cyanide, ammonium carbonate in 1:0.52:1.75 ratio of ingredients. Ammonium bicarbonate was dissolved in 4 times the weight of water and sodium cyanide was dissolved in 3 times the weight of water, then put into the reaction tank, slowly drop add 3-methylthiopropionaldehyde under stirring, the reaction was carried out at 75-80 ℃ for 3H to obtain urea. Hydrolysis of 1.1 parts of lime into milk of lime, Another 0.424 parts of the solution made up of sodium hydroxide is put into the reaction tank, and 1 part of urea is added. The temperature is raised for alkali hydrolysis and ammonia preparation for 1H, keeping the temperature at 165 ℃ and the pressure at 0.5MPa, and reacting for 1H, DL-methionine sodium salt. Neutralization, decolorization the above DL-methionine sodium salt was adjusted to pH5-6 with HCl, and the activated carbon was boiled for 45min at 1%. The residue was removed by hot filtration, and the filtrate was collected, cooled and crystallized, the crude DL-methionine was obtained by drying at 100 °c. The crude product, distilled water, activated carbon and EDTA are added in a ratio of 1:7:0.04:0.0007, and then put into the refining tank, stir, decolorize for 1.5h, and filter to remove the slag, the filtrate was collected, cooled and left to crystallize for 15-20h. The crystals were filtered and dried to obtain the DL-methionine product. |
| toxic substance data | information provided by: pubchem.ncbi.nlm.nih.gov (external link) |
Last Update：2024-04-09 02:00:10
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