''beta''-Alanine

β-Alanine

Names
IUPAC name 3-Aminopropanoic acid
Other names β-Alanine 3-Aminopropionic acid
Identifiers
CAS Number	107-95-9 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:16958 Y
ChemSpider	234 Y
DrugBank	DB03107 Y
ECHA InfoCard	100.003.215
EC Number	203-536-5
IUPHAR/BPS	2365
KEGG	D07561 Y
PubChem CID	239
UNII	11P2JDE17B Y
InChI InChI=1S/C3H7NO2/c4-2-1-3(5)6/h1-2,4H2,(H,5,6) Y Key: UCMIRNVEIXFBKS-UHFFFAOYSA-N Y InChI=1/C3H7NO2/c4-2-1-3(5)6/h1-2,4H2,(H,5,6) Key: UCMIRNVEIXFBKS-UHFFFAOYAL
SMILES O=C(O)CCN
Properties[1][2]
Chemical formula	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)
Solubility in water	54.5 g/100 mL
Solubility	soluble in methanol. Insoluble in diethyl ether, acetone
log P	-3.05
Acidity (pKa)	3.63
Hazards
Main hazards	Irritant
Safety data sheet
NFPA 704	1 2 0
Lethal dose or concentration (LD, LC):
LD50 (median dose)	1000 mg/kg (rat, oral)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y verify (what is YN ?)
Infobox references

β-Alanine (or beta-alanine) is a naturally occurring beta amino acid, which is an amino acid in which the amino group is at the β-position from the carboxylate group (i.e., two atoms away, see Figure 1). The IUPAC name for β-alanine is 3-aminopropanoic acid. Unlike its counterpart α-alanine, β-alanine has no stereocenter.

Biosynthesis and industrial route

In terms of it biosynthesis, it is formed by the degradation of dihydrouracil and carnosine. It is produced industrially by the reaction of ammonia with β-propiolactone.^[3]

Biochemical function

β-Alanine is not found in any major proteins or enzymes. It is a component of the naturally occurring peptides carnosine and anserine and also of pantothenic acid (vitamin B₅), which itself is a component of coenzyme A. Under normal conditions, 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.^[4] 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.^[5][6] 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.^[4]

Figure 1: Comparison of β-alanine (right) with the more customary (chiral) amino acid, L-α-alanine (left)

L-Histidine, with a pK_a of 6.1 is a relatively weak buffer over the physiological intramuscular pH range. However, when bound to other amino acids, this increases nearer to 6.8-7.0. In particular, when bound to β-alanine, the pK_a value is 6.83,^[7] making this a very efficient intramuscular buffer. Furthermore, because of the position of the beta amino group, β-alanine dipeptides are not incorporated into proteins, and thus can be stored at relatively high concentrations (millimolar). Occurring at 17–25 mmol/kg (dry muscle),^[8] 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.

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).^[9]

Athletic performance enhancement

There is evidence that β-alanine supplementation can increase exercise performance, but concern about lack of information about safety.^{[10][11][12][13]}

Ingestion of β-Alanine can cause paraesthesia, reported as a tingling sensation, in a dose-dependent fashion.^[13]

Metabolism

Sources for β-alanine includes pyrimidine catabolism of cytosine and uracil.

β-alanine can undergo a transanimation 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.^[14]

Alternatively, β-alanine can be diverted into Pantothenate and Coenzyme A biosynthesis.^[14]

References

External links

• KEGG map of β-alanine metabolism
• International Society of Sports Nutrition Conference Proceedings