Метионин-L

Описание

Colorless or white lustrous plates, or a white crystalline powder. It has a slight, characteristic odor. It is soluble in water, in alkali solutions, and in dilute mineral acids. It is slightly soluble in alcohol and practically insoluble in ether.

Использование

L-Methionine is used as an essential amino acid for human development and therapeutically acts as an antidote for acetaminophen poisoning. It serves as a chelating agent for heavy metals, as a flavoring agent and nutritional supplement for foods. It acts as a feed additive, vegetable oil enrichment and as a single cell protein. In addition to this, it is used as a hepatoprotectant and also acts as a lipotropic agent and prevents excess fat buildup in the liver.

Методы производства

Numerous methods have been described for manufacture of methionine, including hydrolysis of methionine amide )and 5-(bmethylmercaptoethyl)- hydantoin.

Подготовка

The production method of choice for L-methionine is still the enzymatic resolution of racemic N-acetyl-methionine using acylase from Aspergillus oryzae.  The production is carried out in a  continuously operated fixed-bed or enzyme  membrane reactor.

Определение

ChEBI: L-methionine is the L-enantiomer of methionine. It has a role as a nutraceutical, a micronutrient, an antidote to paracetamol poisoning, a human metabolite and a mouse metabolite. It is an aspartate family amino acid, a proteinogenic amino acid, a methionine and a L-alpha-amino acid. It is a conjugate base of a L-methioninium. It is a conjugate acid of a L-methioninate. It is an enantiomer of a D-methionine. It is a tautomer of a L-methionine zwitterion.

Общее описание

Minute hexagonal plates from dilute alcohol.

Реакции воздуха и воды

Reacts with water, steam, and/or acids to produce toxic and flammable vapors of hydrogen sulfide . Water soluble . pH of 1% aqueous solution is 5.6-6.0.

Профиль реактивности

An organosulfide and amine derivative, carboxylic acid. Look at Reactive Groups 20 (organosulfides), 7 (amines), and 3 (carboxylic acids) may give indications about reactive tendencies. L-Methionine is an amino acid essential in human nutrition.

Угроза здоровью

ACUTE/CHRONIC HAZARDS: L-Methionine is dangerous when heated to decomposition; it emits dangerous and highly toxic fumes.

Пожароопасность

Flash point data for L-Methionine is not available, but L-Methionine is probably combustible.

Фармацевтические приложения

Methionine is used in oral pharmaceutical formulations as a flavoring agent.It has been included in parenteral formulations as a pH controlling agent,and it has also been used experimentally as an antioxidant with antibodies.Methionine is also used therapeutically in oral tablets

Профиль безопасности

Mildly toxic by ingestion and intraperitoneal routes. Human mutation data reported. An experimental teratogen. Experimental reproductive effects. An essential sulfur-containing amino acid. When heated to decomposition it emits very toxic fumes of NOx and SOx.

Безопасность

Methionine is used in oral pharmaceutical formulations. The pure form of methionine is mildly toxic by ingestion and by the IP route.
LD₅₀ (rat, IP): 4.328 g/k
LD₅₀ (rat, oral): 36 g/kg

хранилище

Methionine is sensitive to light and should be stored in a cool, dark place.

Методы очистки

Crystallise L-methionine from aqueous EtOH. Also purify it by dissolving ~0.5g of amino acid in ~10mL of hot H2O, filtering, adjusting the pH to 5.8 with 5N HCl, collecting the solid after addition of ~20mL of EtOH. It is recrystallised by dissolving in H2O and adding EtOH. It sublimes at 197-208o/0.3mm with 99.8% recovery and unracemised [Gross & Gradsky J Am Chem Soc 77 1678 1955]. [Milne & Peng J Am Chem Soc 79 647 1957, Greenstein & Winitz The Chemistry of the Amino Acids J. Wiley, Vol 3 pp 2125-2152 1961, Beilstein 4 IV 3189.]

Несовместимости

Methionine is incompatible with strong oxidizing agents.

Регуляторный статус

Included in the FDA Inactive Ingredients Database (oral tablets). Included in parenteral preparations (injection solutions; powders for reconstitution) licensed in the UK.