Alanine Structure Properties and Biological Role in Chemistry

Alanine is an alpha-amino acid and one of the 21 naturally occurring amino acids. It is quite essential for the biosynthesis of proteins. The three-letter code of alanine is Ala and the amino acid symbol is A. 

The main components of alanine structure are as follows:

1. An amine group

2. A carboxylic group

3. A methyl side chain

Here, both the amine group and the carboxylic group are attached to a central carbon atom which carries a methyl side chain along with it. The form of alanine that is found in every protein that is biologically synthesized is the L alanine (left-handed alanine). It is the most common form of naturally occurring alanine and the skeletal representation of L alanine structure is shown below:

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Hence, the alanine formula is given as C₃H₇NO₂ and the IUPAC or the scientific name based on the alanine structural formula is 2-Aminopropanoic Acid.

What is Alanine?

First synthesized in 1850 by Adolf Strecker who combined acetaldehyde and ammonia along with hydrogen cyanide. The name the amino acid alanine comes from Alanin in German because of the aldehyde with the suffix ‘an’ for easy pronunciation with German prefix ‘in’ that is widely used in the chemical compounds that are analogous to the English ‘ine’. 

The L alanine is the aliphatic amino acid because the side-chain connected to the ɑ-carbon atom is a methyl group (-CH₃). It is an extension of the simplest amino acid glycine because of the attachment of the methyl group. Although the methyl side chain provides a distinct identity to the amino acid, it rarely takes any part in the reaction or the formation of the protein structure. 

The Making and Breaking of Alanine

Alanine amino acid is naturally synthesized by the body. It can be either produced from pyruvate or the branched-chain amino acids such as valine, leucine, and isoleucine. The L alanine is produced or synthesized from the pyruvate by a two-step process which involves the reductive amination - (i) the conversion of the components ɑ-ketoglutarate, ammonia and Nicotinamide adenine nucleotide (NADH) to final products as glutamate, NAD+ by glutamate dehydrogenase. (ii) the transfer of the amino group from the glutamate to the pyruvate by the aminotransferase enzyme along with the regeneration of ɑ-ketoglutarate and the conversion of pyruvate to alanine. Hence, the net result of the two steps is the conversion of pyruvate and ammonia into amino acids. These two reactions are easily possible in the cells and hence, alanine is a non-essential amino acid and hence is closely related to the metabolic pathways such as glycolysis, gluconeogenesis, and the citric acid cycle. 

Chemically, both the forms of alanine, L Alanine and D Alanine can be produced. L Alanine is typically produced by the decarboxylation of the L aspartate through the action of aspartate 4-decarboxylase. The D Alanine is mostly obtained from the racemic mixture of alanine preparation. This racemic mixture, in which the concentration of D Alanine vs L Alanine is mostly similar (~50%), is either produced by the fermentation or mostly by the condensation of acetaldehyde with ammonium chloride in the presence of sodium cyanide (Strecker reaction) or the ammonolysis of 2-bromopropanoic acid. The reactions are given below:

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Chemical Nature of Alanine Structure

As is normally the case with other amino acids, alanine also exists in a zwitterionic form (i.e. an ionic form with both positive and negative charges) which can be seen below:

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The deamination reaction of alanine yields a free radical CH3CHCO2-. This is achieved by the homolytic cleavage of the carbon-nitrogen bond due to radiation. This chemical property arising out of the alanine structure is extensively used in radiotherapy. Whenever the normal alanine is irradiated, a free radical is generated. These free radicals are stable and can be measured by electron paramagnetic resonance. This measurement is biologically relevant as the amount of free radical released reveals the amount of damage a living tissue would incur when exposed to similar conditions of radiation. In treatment plans, alanine pellets delivered inside the body can be measured and thus provides information on whether the intended radiation treatment therapy dose is correctly delivered or not. 

The alanine amino acid is also a potential target during the creation of a gene library, in which each gene has a point mutation at different positions depending on the area of interest and in some cases every position in the whole of the gene into alanine (one after another). This process is known as alanine scanning. This is because of the simplicity of the alanine structure and because of this it was one of the first processes to be done amongst what is collectively identified as ‘scanning mutagenesis’. 

Physiological Alanine Function

The primary function of alanine is the formation of different proteins.

The most important role of alanine is observable in mammals. In mammals, one of the important functions is the glucose-alanine cycle. The alanine function in the cycle is the transfer of the pyruvate from the muscles to the liver. This cycle facilitates the removal of pyruvate and glutamate from the muscle cells and the transportation of pyruvate in the form of aniline to the liver. In the liver, pyruvate is used for the regeneration of glucose. This glucose is then returned to the muscle for utilisation and metabolization for energy requirements. 

Because of this system, the energetic burden of producing glucose falls on the liver instead of the muscles and therefore all the available ATP in the muscles can be used for muscle contraction. The importance of alanine transportation in the glucose-alanine cycle is shown by the fact that alterations in the cycle can lead to an increase in the levels of alanine aminotransferase in the blood serum which is a characteristic of the development of Type II diabetes. 

The Properties of Alanine

To be precise, alanine is a hydrophobic molecule. Furthermore, alanine is ambivalent, which means it can be located either inside or outside the protein molecule. The alpha-carbon of alanine is usually active. 

The properties of alanine resemble most other amino acids present in the human body. For instance, one of the main properties of alanine is its L-isomerism. It is worth mentioning here that alanine is the alpha-amino acid of the alpha-keto acid pyruvate. Both pyruvate and alanine are interchangeable via the transmission reaction. 

The beta alanine benefits are primarily due to phosphorylation. It exhibits a range of chemical properties. For instance, the hydrogenation of alanine will provide amino alcohol alaninol. In case you don’t know, alaninol is a functional chiral building block. 

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The Beta Alanine Benefits at a Glance 

To be precise, you should be aware of the beta alanine benefits to maintain proper health and wellbeing. It is a popular form of supplement among athletes and fitness freaks. This is because beta-alanine can enhance performance in sportspersons and athletes by decreasing the formation of lactic acid formation in muscles. 

And as you know, when there is less lactic acid production in the muscles, our body’s endurance will grow. In other words, performing strenuous physical exercises becomes accessible in the presence of beta-alanine. Note that beta-alanine is a non-essential amino acid. Unlike most amino acids, it is usually ignored by our bodies for protein synthesis. 

However, in the presence of histidine, it develops carnosine. Carnosine is usually stored in the skeletal muscles. Moreover, beta-alanine can increase the level of carnosine which decreases acidity in your muscles during high-intensity physical exercises. This is one of the main benefits of beta alanine. 

The Amino Acid Function in Human Body 

You should be aware of the amino acid function to realise its importance. Here is the list of functions performed by amino acids in the human body. 

• The primary amino acid function is to act as chemicals in the form of brain messengers. For instance, phenylalanine helps in forming the structure and functioning of proteins of essential brain chemicals like dopamine. 

• Another amino acid function is to maintain the proper balance of nitrogen in our bodies. For instance, the amino acid Tryptophan assists our body to regulate the level of nitrogen. It also helps with the synthesis of neurotransmitters. 

• The amino acids in the body can assist with the growth of tissues and proper metabolism. Moreover, they can help our body detox properly. The amino acids in the body also aid with the absorption of essential minerals like selenium and zinc. 

Conclusion

The amino acids in the body, like Histidine, help with the synthesis of neurotransmitters. Moreover, it helps our body to fortify its immune system. Histidine also aids with proper sleep and digestion. It also maintains the myelin sheath. The myelin sheath is the protective barrier around nerve cells.