Alanine

Chemical structure of L-alanine
Alanine
Systematic (IUPAC) name
(S)-2-aminopropanoic acid
Identifiers
CAS number	56-41-7
PubChem	5950
Chemical data
Formula	O₂
Molar mass	89.1 g/mol
SMILES	C[C@H](N)C(O)=O
Complete data

Alanine (abbreviated as Ala or A)^[1] is an α-proteins.^[2] D-alanine occurs in bacterial cell walls and in some peptide antibiotics.

Structure

The aliphatic amino acid. The methyl group of alanine is non-reactive and is thus almost never directly involved in protein function.

Sources

Dietary Sources

Alanine 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 souces: 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.

Biosynthesis

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 citric acid cycle. It also arises together with lactate and generate glucose from protein via the alanine cycle.

Chemical Synthesis

Strecker reaction.^[3]

Physiological function

As a carrier of ammonia and of the carbon skeleton of pyruvate in alanine cycle

Alanine 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 urea.^[4]

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 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.^[4]

Chemical Properties

Free Radical Stability

One very unusual property of the alanine molecule is that it forms a stable chemistry.

This property of alanine is used 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.

References

^ IUPAC-IUBMB Joint Commission on Biochemical Nomenclature. Nomenclature and Symbolism for Amino Acids and Peptides. Recommendations on Organic & Biochemical Nomenclature, Symbols & Terminology etc. Retrieved on 2007-05-17.
^ Doolittle, R. F.; & Fasman G.D. (ed.) (1989). "Redundancies in protein sequences" in Prediction of Protein Structures and the Principles of Protein Conformation. New York: Plenum Press, pp. 599-623.
^ Kendall, E. C.; McKenzie, B. F. “dl-Alanine” Organic Syntheses, Collected Volume 1, p.21 (1941). http://www.orgsyn.org/orgsyn/pdfs/CV1P0021.pdf
^ ^a ^b Nelson, D. L. & Cox, M. M. (2005). Lehninger Principles of Biochemistry, 4th Edition. New York: W. H. Freeman and Company, pp. 684-685. ISBN 0-7167-4339-6.