alanine n : a crystalline amino acid that occurs in many proteins
nonessential amino acid; C3H7NO2
- Italian: alanina
- Portuguese: alanina
- Spanish: alanina
- Plural of alanina
Alanine (abbreviated as Ala or A) is an α-amino acid with the chemical formula HO2CCH(NH2)CH3. The L-isomer is one of the 20 proteinogenic amino acids, i.e. the building blocks of proteins. Its codons are GCU, GCC, GCA, and GCG. It is classified as a non-polar amino acid. L-alanine is second only to leucine, accounting for 7.8% of the primary structure in a sample of 1,150 proteins. D-alanine occurs in bacterial cell walls and in some peptide antibiotics.
StructureThe α-carbon atom of alanine is bound with a methyl group (-CH3), making it one of the simplest α-amino acids with respect to molecular structure and also resulting in alanine being classified as an aliphatic amino acid. The methyl group of alanine is non-reactive and is thus almost never directly involved in protein function.
Dietary SourcesAlanine is a nonessential amino acid, meaning it can be manufactured by the human body, and does not need to be obtained directly through the diet. Alanine is found in a wide variety of foods, but is particularly concentrated in meats.
Good sources of alanine include:
- Animal sources: meat, seafood, caseinate, dairy products, eggs, fish, gelatin, lactalbumin
- Vegetarian sources: beans, nuts, seeds, soy, whey, brewer's yeast, brown rice bran, corn, legumes, whole grains.
Alanine can be manufactured in the body from pyruvate and branched chain amino acids such as valine, leucine, and isoleucine.
Alanine is most commonly produced by reductive amination of pyruvate. Because transamination reactions are readily reversible and pyruvate pervasive, alanine can be easily formed and thus has close links to metabolic pathways such as glycolysis, gluconeogenesis, and the citric acid cycle. It also arises together with lactate and generates glucose from protein via the alanine cycle.
Chemical SynthesisRacemic alanine can be prepared via the condensation of acetaldehyde with ammonium chloride in the presence of potassium cyanide by the Strecker reaction.
As a carrier of ammonia and of the carbon skeleton of pyruvate in alanine cycleAlanine plays a key role in glucose-alanine cycle between tissues and liver. In muscle and other tissues that degrade amino acids for fuel, amino groups are collected in the form of glutamate by transamination. Glutamate can then transfer its amino group through the action of alanine aminotransferase to pyruvate, a product of muscle glycolysis, forming alanine and alpha-ketoglutarate. The alanine formed is passed into the blood and transported to the liver. A reverse of the alanine aminotransferase reaction takes place in liver. Pyruvate regenerated forms glucose through gluconeogenesis, which returns to muscle through the circulation system. Glutamate in the liver enters mitochondria and degrades into ammonium ion through the action of glutamate dehydrogenase, which in turn participate in the urea cycle to form urea.
Glucose-alanine cycle enables pyruvate and glutamate to be removed from muscle and find their ways to liver. Glucose is able to be regenerated from pyruvate and returned to muscle. The energetic burden of gluconeogenesis is thus imposed on the liver instead of the muscle. All available ATP in muscle is devoted to muscle contraction.
Free radical stabilityThe deamination of an alanine molecule produces a stable alkyl free radical, CH3C•HCOO–. Deamination can be induced in solid or aqueous alanine by radiation.
This property of alanine is used in dosimetric measurements in radiotherapy. When normal alanine is irradiated, the radiation causes certain alanine molecules to become free radicals, and, as these radicals are stable, the free radical content can later be measured in order to find out how much radiation the alanine was exposed to. In this way, one can be assured that complex radiotherapy treatment plans will deliver the intended pattern of radiation dose.
alanine in Bengali: অ্যালানিন
alanine in Catalan: Alanina
alanine in Czech: Alanin
alanine in Danish: Alanin
alanine in German: Alanin
alanine in Modern Greek (1453-): Αλανίνη
alanine in Spanish: Alanina
alanine in Esperanto: Alanino
alanine in French: Alanine
alanine in Galician: Alanina
alanine in Korean: 알라닌
alanine in Croatian: Alanin
alanine in Indonesian: Alanin
alanine in Italian: Alanina
alanine in Hebrew: אלנין
alanine in Latvian: Alanīns
alanine in Luxembourgish: Alanin
alanine in Lithuanian: Alaninas
alanine in Hungarian: Alanin
alanine in Dutch: Alanine
alanine in Japanese: アラニン
alanine in Pushto: آلانين
alanine in Polish: Alanina
alanine in Portuguese: Alanina
alanine in Romanian: Alanină
alanine in Russian: Аланин
alanine in Slovak: Alanín
alanine in Serbian: Аланин
alanine in Sundanese: Alanin
alanine in Finnish: Alaniini
alanine in Swedish: Alanin
alanine in Turkish: Alanin
alanine in Ukrainian: Аланін
alanine in Chinese: 丙氨酸