Amino acids

Amino acids are organic acids whose molecules contain one or more amino groups (NH2). Amino acids are the building blocks of proteins and are exempt from when the hydrolysis. In hydrolyzed proteins are found more than 20 amino acids. Amino acids are a key part of the nitrogen metabolism and serve as a source of formation of the final products of nitrogen metabolism (urea, ammonia and other) and the number needed for the life of substances: proteins, peptides, purine and pyrimidine bases, hormones and other biologically active compounds. All amino acids - white crystalline substance, different [from Gorky (leucine) to sweet (glycine)] of taste; melt at relatively high temperatures, often with decomposition. Most of the amino acid dissolves well in water, especially when acidification or alkalization.
Amino acids are both amines and acids and therefore possess chemical properties of these classes of compounds. As acids amino acids form salts with bases, and salts of heavy metals (especially copper, mercury, silver) are often insoluble and are used in the analysis and selection of amino acids. Like amines, amino acids form salts with acids; under the influence of nitrous acid amino acids are deamination with the formation of molecular nitrogen and hydroxy acids.
Important role in the exchange of amino acids plays reactions of transamination, consisting in the transfer of the amino group with amino acids to ketoacid, resulting in another amino acid. A necessary component of the reactions of transamination taking place under the action of enzymes of aminotransferases are dicarboxylic amino acids. Thanks to the reaction of dicarboxylic amino acids and their amides link exchange of amino acids and oxidizing conversion of carbohydrates and fats.
Amino acids, not synthesized in the human body, but necessary for normal life, called essential amino acids. These include: valine, leucine, isoleucine, threonine, methionine, phenylalanine, tyrosine, tryptophan, lysine. These amino acids enter the body with food.
Getting into the blood from the intestines, amino acids come in all organs and tissues, where they are used to synthesize proteins and are exposed to various transformations. In the blood is maintained at a constant level amino nitrogen (about 6-8 mg % in whole blood and about 4-6 mg % in plasma or serum). In the blood concentration of Amino acids is always higher than in plasma and varies in wide range.
Determination of amino acids in the blood is set in clinical practice, allowing to judge the state of the liver and kidneys. The content of amino acids in the blood can significantly grow in toxicosis of pregnancy, a violation of kidney function, diseases associated with increased protein breakdown (fever, cancer , etc). In tissues (muscles, brain, liver) the content of free amino acids are many times higher than in blood, and less constantly. It depends on what the tissue cells are able to concentrate amino acids from the environment, more poor them.
Many amino acids are finding use in medicine. Different protein hydrolysates and mixtures of amino acids are appointed for parenteral nutrition (see Protein hydrolysates).