Β-Alanine Explained

β-Alanine (or beta-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.

Biosynthesis and industrial route

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.[1] It is produced industrially by the reaction of ammonia with β-propiolactone.

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

Biochemical function

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.

Precursor of carnosine

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.[2] 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.[3] [4] 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.[2]

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),[5] 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.[6]

Receptors

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).[7]

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."[8]

Athletic performance enhancement

There is evidence that β-alanine supplementation can increase exercise and cognitive performance,[9] [10] [11] for some sporting modalities,[12] and exercises within a 0.5–10 min time frame.[13] 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.[14]

Ingestion of β-alanine can cause paraesthesia, reported as a tingling sensation, in a dose-dependent fashion.[15] 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. Furthermore, many studies have failed to test for the purity of the supplements used and check for the presence of banned substances.

Metabolism

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.[16]

Alternatively, β-alanine can be diverted into pantothenic acid and coenzyme A biosynthesis.

External links

Notes and References

  1. Wright. Margaret Robson. Arrhenius parameters for the acid hydrolysis of esters in aqueous solution. Part I. Glycine ethyl ester, β-alanine ethyl ester, acetylcholine, and methylbetaine methyl ester. Journal of the Chemical Society B: Physical Organic. 1969. 707–710. 10.1039/J29690000707.
  2. Web site: Beta-Alanine Supplementation For Exercise Performance. 21 September 2018. 20 June 2017. https://web.archive.org/web/20170620082252/http://www.pharmacistanswers.com/beta-alanine-supplementation-for-exercise-performance.html. dead.
  3. Derave W, Ozdemir MS, Harris R, Pottier A, Reyngoudt H, Koppo K, Wise JA, Achten E . Beta-alanine supplementation augments muscle carnosine content and attenuates fatigue during repeated isokinetic contraction bouts in trained sprinters . J Appl Physiol . August 9, 2007 . 17690198 . 10.1152/japplphysiol.00397.2007 . 103. 5 . 1736–43 . 6990201 .
  4. Hill CA, Harris RC, Kim HJ, Harris BD, Sale C, Boobis LH, Kim CK, Wise JA . Influence of beta-alanine supplementation on skeletal muscle carnosine concentrations and high intensity cycling capacity . Amino Acids . 2007 . 2 . 32 . 225–33 . 16868650 . 10.1007/s00726-006-0364-4 . 23988054 .
  5. 10.1007/BF00376439 . 1735411 . Mannion . AF . Jakeman . PM . Dunnett . M . Harris . RC . Willan . PLT . 1992 . Carnosine and anserine concentrations in the quadriceps femoris muscle of healthy humans . Eur. J. Appl. Physiol . 64 . 1. 47–50 . 24590951 .
  6. Bate-Smith . EC . 1938 . The buffering of muscle in rigor: protein, phosphate and carnosine . Journal of Physiology . 92 . 3. 336–343 . 16994977 . 1395289 . 10.1113/jphysiol.1938.sp003605 .
  7. Encyclopedia of Life Sciences Amino Acid Neurotransmitters. Jeremy M Henley, 2001 John Wiley & Sons, Ltd., Article Online Posting Date: April 19, 2001
  8. Tiedje KE, Stevens K, Barnes S, Weaver DF . Beta-alanine as a small molecule neurotransmitter . Neurochem Int . 57 . 3 . 177–88 . October 2010 . 20540981 . 10.1016/j.neuint.2010.06.001 . 7814845 .
  9. Quesnele JJ, Laframboise MA, Wong JJ, Kim P, Wells GD . The effects of beta-alanine supplementation on performance: a systematic review of the literature . Int J Sport Nutr Exerc Metab . 24 . 1 . 14–27 . 2014 . 23918656 . 10.1123/ijsnem.2013-0007 . Systematic review.
  10. Hoffman JR, Stout JR, Harris RC, Moran DS . β-Alanine supplementation and military performance . Amino Acids . 47 . 12 . 2463–74 . 2015 . 26206727 . 4633445 . 10.1007/s00726-015-2051-9 .
  11. Hobson . R. M. . Saunders . B. . Ball . G. . Harris . R. C. . Sale . C. . Effects of β-alanine supplementation on exercise performance: a meta-analysis . Amino Acids. 9 December 2016 . 43 . 1 . 25–37. 10.1007/s00726-011-1200-z. 3374095. 0939-4451. 22270875.
  12. Ergogenic Effects of β-Alanine Supplementation on Different Sports Modalities: Strong Evidence or Only Incipient Findings? . Gabriel M P . Brisola . Alessandro M . Zagatto . . 2019 . 33 . 1 . 253–282 . 30431532 . 10.1519/JSC.0000000000002925 . 53441737 .
  13. β-alanine supplementation to improve exercise capacity and performance: a systematic review and meta-analysis FREE . Bryan Saunders . Kirsty Elliott-Sale . Guilherme G Artioli1 . Paul A Swinton . Eimear Dolan . Hamilton Roschel . Craig Sale . Bruno Gualano. British Journal of Sports Medicine . 2017 . 51 . 8 . 658–669 . 27797728 . 10.1136/bjsports-2016-096396 . 25496458 . free. 10059/1913 . free .
  14. Med Sci Sports Exerc . June 2010 . 42 . 6 . 1162–73 . Role of beta-alanine supplementation on muscle carnosine and exercise performance . Guilherme Giannini Artioli . Bruno Gualano . Abbie Smith . Jeffrey Stout . Antonio Herbert Lancha Jr. . 10.1249/MSS.0b013e3181c74e38 . 20479615. free .
  15. Trexler ET, Smith-Ryan AE, Stout JR, Hoffman JR, Wilborn CD, Sale C, Kreider RB, Jäger R, Earnest CP, Bannock L, Campbell B, Kalman D, Ziegenfuss TN, Antonio J . International society of sports nutrition position stand: Beta-Alanine . J Int Soc Sports Nutr . 12 . 30 . 2015 . 26175657 . 4501114 . 10.1186/s12970-015-0090-y . free . Review.
  16. Web site: KEGG PATHWAY: beta-Alanine metabolism - Reference pathway. www.genome.jp. 2016-10-04.

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