What is alanine?
Alanine is a proteinogenic amino acid. It can be synthesized by the human organism and is therefore nonessential. The amino acid called alanine is actually called alpha-L-alanine. In this name, the position of the amino group with respect to the carboxyl group becomes clear.
In addition, only the L-form of alanine is used for protein synthesis. The D-form is used by bacteria for the synthesis of murein, which forms the cell membrane of the bacteria. Another amino acid in this context is beta-alanine. Here the amino group is on the beta carbon atom. Beta-alanine is not a proteinogenic amino acid. But it also plays a big role in biological processes. However, when Alanin is spoken here, it is always alpha-L-alanine.
Alanine has a positive center on the nitrogen atom and a negative center on an oxygen atom of the carboxyl group. Thus, alanine is a zwitterion. At the isoelectric point of alanine at a pH of 6.1, almost all molecules exist as zwitterions. Therefore, under these conditions, its water solubility is lowest. However, alanine is a hydrophilic amino acid and, by virtue of this property, also determines the secondary and tertiary structure of the proteins.
Function, effect & tasks
The most important function of alanine is to be involved as a building block in protein building. The structure of alanine makes it preferentially occur in the alpha helix of the protein. Together with the amino acids glutamic acid or leucine, alanine thus determines the formation of the helical and thus also the secondary structure of the protein.
In metabolism, alanine is synthesized from pyruvate by transamination. Pyruvate is an intermediate of metabolism. It is produced by the breakdown of sugar, fatty acids or amino acids. Either it is further degraded or it serves again as starting material for further syntheses. The degradation of alanine functions as a reverse reaction to the transamination of pyruvate. The enzyme alanine dehydrogenase alanine is deaminated to pyruvate again. Since pyruvate can also be quickly converted back into glucose, the close link between amino acid metabolism and carbohydrate metabolism becomes clear. If there is a sudden need for energy, hypoglycaemia can occur for a short time. This releases stress hormones, which in the liver stimulate the deamination of alanine and the conversion of pyruvate to glucose.
Through this process, the blood sugar level is kept constant. Due to this fact, alanine supplements are often given in hypoglycaemia in order to avoid a sugar shock. Alanine also has a strengthening effect on the immune system. It also inhibits the formation of kidney stones. Alanine is a key component of muscle proteins. The muscle fibers contain up to 6 percent alanine. By breaking down the muscles, it is released again.
The blood-containing alanine comes to 30 percent of the muscles. The main metabolism organ is the liver. In the liver, most alanine conversion reactions take place. Via the liver metabolism, the amino acid regulates insulin production. Furthermore, decongestant effects on the prostate were noted.
Education, occurrence, properties & optimal values
High levels of alanine are found in meat and fish products. Mushrooms, sunflower seeds, soybean meal, wheat germ or even parsley have a high alanine content. Normally, the amount of alanine produced and ingested by the body is quite sufficient. Due to its water solubility, alanine is washed out of the food during prolonged contact with water.
For this reason, alanine-rich products should never be soaked or cooked for long. Deficiencies are rare. However, there is an increased need for alanine in competitive sports, so that an additional application over protein-rich food or protein powder may be useful. In any case, the training success is positively influenced by alanine. It is present in high concentrations both in the muscle fibers and in the connective tissue.
Diseases & Disorders
The health effects of an alanine deficiency on the body have hardly been investigated. Such a deficiency condition can usually only occur in extreme malnutrition. In this case, however, there is no isolated alanine deficiency.
Alanine is generally available to the body both through the diet and through the body's own biosynthesis. Alanine synthesis takes place in the liver. The same applies to the breakdown of alanine. For this, the enzyme alanine aminotransferase is available in the liver. Alanine aminotransferase is a transaminase and is known by the abbreviation GPT. GPT catalyzes the conversion of L-alanine with alpha-ketoglutarate. The amino group is transferred to alpha-ketoglutarate to form L-glutamate. Alanine produces pyruvate. These reactions take place within the liver cells. The transaminase is therefore present in the blood only in low concentration.
An increase in the enzyme concentration in the blood indicates a destruction of the liver cells. Apart from GPT (alanine aminotransferase or newly glutamate pyruvate transaminase), other enzyme values are also increased. It is spoken by increasing the liver values. The liver values make it possible to diagnose liver diseases. The first sign of liver disease may be the elevation of liver enzymes. This applies to all forms of hepatitis, liver cirrhosis or even liver cancer. As liver disease progresses, the organ can no longer perform its multiple metabolic and detoxification tasks.