Alanine: Definition, Function, Structure, Properties and Natural Sources

It is one of the main amino acids discovered and synthesized long before its isolation from natural sources.

In 1850, this amino acid was synthesized by Adolph Strecker from acetaldehyde through its condensation using ammonia and hydrogen cyanide.

Only in a quarter of a century, alanine was discovered in natural sources such as proteins.

Function

It is basically a non-essential amino acid that is sometimes found at high levels in its free state in human plasma .

In mammals it plays a key role in the glucose-alanine cycle between the tissues and the liver.

In muscles and other tissues that degrade amino acids as fuel, amino groups are collected in the form of glutamate by transamination.

Glutamate can then transfer its amino group to pyruvate, a product of muscle glycolysis, through the action of alanine aminotransferase, forming alanine and α-ketoglutarate.

Alanine enters the bloodstream and is transported to the liver.

The alanine aminotransferase reaction takes place in reverse in the liver, where the regenerated pyruvate is used in gluconeogenesis, forming glucose that returns to the muscles through the circulation system.

Glutamate in the liver enters the mitochondria and is broken down by glutamate dehydrogenase into α-ketoglutarate and ammonium, which in turn participates in the urea cycle to form urea that is excreted through the kidneys.

The glucose-alanine cycle allows the pyruvate and glutamate to be removed from the muscle and transported safely to the liver, where glucose is regenerated from pyruvate and then returned to the muscle, this moves the energy load of gluconeogenesis to the liver in place of the muscle, and all available ATP in the muscle can be devoted to muscle contraction.

It is a catabolic pathway, and is based on the breakdown of proteins in muscle tissue. It is not clear if this is the same and / or to what extent it occurs in non-mammals.

It is also known to increase immunity and provide energy for the brain, the central nervous system and for muscle tissue.

In short, alanine helps your body convert simple sugar called glucose into the energy it needs, while eliminating excess toxins from your liver.

As is known, amino acids are the building blocks of proteins, thus becoming the key to building muscles, and alanine is also on the list, which helps protect cells from damage during intense physical activity.

Then, due to the fact that the fluid in the prostate gland contains this amino acid, it was suggested that alanine might help treat benign prostatic hyperplasia, which is the condition in which the prostate is enlarged .

Structure

It is an aliphatic amino acid, because the side chain connected to the α-carbon atom is a methyl group (-CH3), so it is the simplest α-amino acid except for glycine .

The methyl side chain of alanine is not reactive and, therefore, almost never participates directly in the function of the protein.

Because the alanine side chain can not be phosphorylated (only compounds such as 3-phosphino-L-alanine and 3-hydroxyphosphinilalanine are known), it is useful in loss-of-function experiments with respect to phosphorylation.

Some techniques involve the creation of a gene library, each of which has a point mutation in a different position in the area of ​​interest, sometimes even in all positions of the complete gene, this is called “sweep mutagenesis”.

The simplest method, and the first one used, is the so-called “alanine scan”, where each position in turn is mutated to alanine.

Chemical properties

Stability of free radicals:

The deamination of an alanine molecule produces a stable free alkyl radical, CH3C • HCOO-. Deamination can be induced in solid or aqueous alanine by radiation.

This property of alanine is used in dosimetric measurements in radiotherapy.

When normal alanine is irradiated, the radiation causes certain alanine molecules to become free radicals and, since these radicals are stable, the free radical content can be measured later by paramagnetic electron resonance in order to find out how much radiation was exposed the alanine.

This is considered a biologically relevant measure of the amount of radiation damage that living tissue would suffer under the same exposure to radiation.

Radiation therapy treatment plans can be administered in test mode to alanine granules, which can then be measured to verify that the treatment system applies the correct radiation dose.

Sources of Alanine

Foods:

As mentioned above, alanine is a non-essential amino acid, that is, a healthy body can produce it for its own needs.

However, it can become an essential amino acid (which means you would need a dietary supplement) if your body can not manufacture it for some reason.

To avoid this deficiency, people with low protein diets or eating disorders, as well as those suffering from liver disease or diabetes, may need to take supplements of this amino acid.

To be healthy, the human body requires alanine to process vitamin B.

Naturally, you can obtain this amino acid from sources such as meat, poultry, eggs, dairy products and fish.

Vegetarians are recommended to eat plant foods rich in proteins, for example, avocados, as they also supply alanine.

Biosynthesis:

Alanine can be synthesized from pyruvate and branched chain amino acids such as valine, leucine and isoleucine.

Alanine is most often produced by pyruvate reductive amination, a two-step process.

In the first step, α-ketoglutarate, ammonia and NADH are converted by glutamate dehydrogenase into glutamate, NAD + and water.

In the second step, the amino group of the newly formed glutamate is transferred to pyruvate by an aminotransferase enzyme, regenerating α-ketoglutarate and converting pyruvate to alanine.

The net result is that pyruvate and ammonia are converted to alanine, consuming a reducing equivalent.

Because transamination reactions are easily reversible and pyruvate is present in all cells, alanine can be easily formed and, therefore, has close links to metabolic pathways, such as glycolysis, gluconeogenesis, and the cytoplasm cycle. citric acid.

Chemical synthesis:

Racemic alanine can be prepared by the condensation of acetaldehyde with ammonium chloride in the presence of sodium cyanide by the Strecker reaction or by the ammonolysis of 2-bromopropanoic acid.

Degradation:

Alanine is decomposed by oxidative deamination, the reverse reaction of the reductive amination reaction described above, catalyzed by the same enzymes.

The direction of the process is largely controlled by the relative concentration of the substrates and products of the reactions involved.

Diabetes:

Alterations in the alanine cycle that increase the levels of alanine aminotransferase (ALT) in serum are related to the development of type II diabetes.