Thanks to aminotransferasestransfer of NH2-groups from the donor γ-amino acid to the acceptor-α-amino acid without intermediate ammonium formation. That is, transamination (reamination: reversible transfer of amino groups to keto acids) is a process discovered by the famous Russian scientists Braunstein and Kritzman.
Amino acids (aspartic, glutamic andalanine) in the process of transamination are converted into the corresponding α-keto acids, which are components of the tricarboxylic acid cycle. When they are oxidized in the Krebs cycle, they serve as a source of energy.
Transamination is also essential in the maintenance of the urea cycle with aspartate.
Despite the fact that the transamination reactionsaromatic amino acids can also be exposed: phenylalanine, tyrosine and tryptophan, - practical use in medicine has found only the determination of the activity of aspartate and alanine aminotransferase. These enzymes are widely distributed in the tissues of the human body.
Alanine aminotransferase is increased in erythrocytes and its concentration is six times higher than that in serum. The highest concentration of this enzyme is found in liver tissues.
Alanine aminotransferase is the norm for tissueshuman body is not the same. For example, the activity of the enzyme in the heart tissues is 7.1 (E * 10-3 g tissue homogenate), in the liver - 44, skeletal muscle - 4.8, kidneys - 19, spleen - 1.2, lung 0.7 and serum - 0.016. The existing methods for determining the activity of aminotransferases in the blood serum are divided into two groups: the endpoint (colorimetric, using conventional photometric equipment that is not equipped with thermostatically controlled cells) and kinetic (spectrophotometric) methods.
B6 is a widely distributed vitamin ina variety of food products. However, it should be remembered that in the process of cooking (thermal block), this vitamin is destroyed. Pyridoxine is the cofactor of most enzymes. The concentration of pyrodoxin-5-phosphate in the blood decreases with age. Therefore, the activity of an enzyme such as alanine aminotransferase is lower in people older than 64 years (approximately 30%) than at the age of 46-63 years. The concentration of vitamin B6 in the blood serum determines the activity of alanine aminotransferase.
To determine the functional state of the liverVery often, the level of aminotransferases in a patient's blood is examined. This is due primarily to the fact that the change in their activity occurs much faster than other laboratory indicators. Elimination (exit) of liver enzymes in the blood is a sign of cytolysis - the destruction of cells or the violation of the permeability of their membranes. When analyzing changes in enzyme activity, it is important to establish a place for elimination. For this it is necessary to know their activity in the blood and cells of a healthy organism, intracellular localization and metabolism. The concentration of the enzyme - alanine aminotransferase is increased, especially in liver cells, so even a slight damage to them provokes an increase in the enzyme activity in the blood. Taking into account the activity of the enzyme, liver diseases (hepatitis, hepatosis) are diagnosed.
Alanine aminotransferase increased with necrosisliver, as well as with parenchymal hepatitis. A low concentration of the enzyme is recorded in chronic hepatitis and dystrophy. It should be noted that the increase in serum aminotransferase activity begins 3-8 days before the appearance of the main clinical signs of the disease and reaches its maximum values in the early days of the development of the pathological process.
So, alanine aminotransferase is increased: cirrhosis of the liver, mechanical jaundice, liver cancer, myocardial infarction, right heart failure, hypoxia, shock, myositis, myocarditis, fatty hepatosis, pancreatin, chronic alcoholism.</ p>