β-Alanine (orbeta-alanine) is a naturally occurring beta amino acid, which is an amino acid in which the amino group is attached to the β-carbon (i.e. the carbon two carbon atoms away from the carboxylate group) instead of the more usual α-carbon for alanine (α-alanine). The IUPAC name for β-alanine is 3-aminopropanoic acid. Unlike its counterpart α-alanine, β-alanine has no stereocenter.
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Names | |
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IUPAC name
β-Alanine | |
Systematic IUPAC name
3-Aminopropanoic acid | |
Other names
3-Aminopropionic acid | |
Identifiers | |
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3D model (JSmol) |
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ChEBI | |
ChEMBL | |
ChemSpider |
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DrugBank |
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ECHA InfoCard | 100.003.215 ![]() |
EC Number |
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KEGG |
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PubChem CID |
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UNII | |
CompTox Dashboard (EPA) |
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Properties[2][3] | |
C3H7NO2 | |
Molar mass | 89.093 g/mol |
Appearance | white bipyramidal crystals |
Odor | odorless |
Density | 1.437 g/cm3 (19 °C) |
Melting point | 207 °C (405 °F; 480 K) (decomposes) |
54.5 g/100 mL | |
Solubility | soluble in methanol. Insoluble in diethyl ether, acetone |
log P | -3.05 |
Acidity (pKa) |
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Hazards | |
Occupational safety and health (OHS/OSH): | |
Main hazards |
Irritant |
NFPA 704 (fire diamond) | |
Lethal dose or concentration (LD, LC): | |
LD50 (median dose) |
1000 mg/kg (rat, oral) |
Safety data sheet (SDS) | [1] |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
In terms of its biosynthesis, it is formed by the degradation of dihydrouracil and carnosine. β-Alanine ethyl ester is the ethyl ester which hydrolyses within the body to form β-alanine.[4] It is produced industrially by the reaction of ammonia with β-propiolactone.[5]
Sources for β-alanine includes pyrimidine catabolism of cytosine and uracil.
β-Alanine residues are rare. It is a component of the peptides carnosine and anserine and also of pantothenic acid (vitamin B5), which itself is a component of coenzyme A. β-alanine is metabolized into acetic acid.
β-Alanine is the rate-limiting precursor of carnosine, which is to say carnosine levels are limited by the amount of available β-alanine, not histidine.[6] Supplementation with β-alanine has been shown to increase the concentration of carnosine in muscles, decrease fatigue in athletes, and increase total muscular work done.[7][8] Simply supplementing with carnosine is not as effective as supplementing with β-alanine alone since carnosine, when taken orally, is broken down during digestion to its components, histidine and β-alanine. Hence, by weight, only about 40% of the dose is available as β-alanine.[6]
Because β-alanine dipeptides are not incorporated into proteins, they can be stored at relatively high concentrations. Occurring at 17–25 mmol/kg (dry muscle),[9] carnosine (β-alanyl-L-histidine) is an important intramuscular buffer, constituting 10-20% of the total buffering capacity in type I and II muscle fibres. In carnosine, the pKa of the imidazolium group is 6.83, which is ideal for buffering.[10]
Even though much weaker than glycine (and, thus, with a debated role as a physiological transmitter), β-alanine is an agonist next in activity to the cognate ligand glycine itself, for strychnine-sensitive inhibitory glycine receptors (GlyRs) (the agonist order: glycine ≫ β-alanine > taurine ≫ alanine, L-serine > proline).[11]
β-alanine has five known receptor sites, including GABA-A, GABA-C a co-agonist site (with glycine) on NMDA receptors, the aforementioned GlyR site, and blockade of GAT protein-mediated glial GABA uptake, making it a putative "small molecule neurotransmitter."[12]
There is evidence that β-alanine supplementation can increase exercise and cognitive performance,[13][14][15][16] for some sporting modalities,[17] and exercises within a 0.5–10 min time frame.[18] β-alanine is converted within muscle cells into carnosine, which acts as a buffer for the lactic acid produced during high-intensity exercises, and helps delay the onset of neuromuscular fatigue.[15][19]
Ingestion of β-alanine can cause paraesthesia, reported as a tingling sensation, in a dose-dependent fashion.[16] Aside from this, no important adverse effect of β-alanine has been reported, however, there is also no information on the effects of its long-term usage or its safety in combination with other supplements, and caution on its use has been advised.[13][14] Furthermore, many studies have failed to test for the purity of the supplements used and check for the presence of banned substances.[15]
β-Alanine can undergo a transamination reaction with pyruvate to form malonate-semialdehyde and L-alanine. The malonate semialdehyde can then be converted into malonate via malonate-semialdehyde dehydrogenase. Malonate is then converted into malonyl-CoA and enter fatty acid biosynthesis.[20]
Alternatively, β-alanine can be diverted into pantothenic acid and coenzyme A biosynthesis.[20]
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