transaminaaseille

Transaminases, also known as aminotransferases, are a class of enzymes that play a crucial role in metabolism by catalyzing the transfer of an amino group (NH₂) from an amino acid to an α-keto acid, resulting in the formation of a new amino acid and a new α-keto acid. This process is essential for amino acid synthesis, degradation, and the interconversion of various metabolites within cells.

The two most clinically significant transaminases are alanine aminotransferase (ALT) and aspartate aminotransferase (AST). ALT transfers an amino group from alanine to α-ketoglutarate, producing pyruvate and glutamate, while AST transfers an amino group from aspartate to α-ketoglutarate, yielding oxaloacetate and glutamate. These enzymes are primarily found in the liver, heart, skeletal muscle, kidneys, and brain, with ALT being more specific to the liver and AST found in a broader range of tissues.

Transaminases are commonly measured in blood tests to assess liver function and detect potential liver damage or disease. Elevated levels of ALT and AST in the bloodstream may indicate conditions such as hepatitis, cirrhosis, fatty liver disease, or alcohol-related liver injury. However, other factors, including muscle injury, heart attack, or certain medications, can also influence transaminase levels. AST can also be elevated in conditions affecting skeletal muscle or the heart, such as myocardial infarction.

Transaminase activity is dependent on the presence of cofactors, particularly pyridoxal phosphate (PLP), a derivative of vitamin B6. Deficiencies in vitamin B6 can impair transaminase function, leading to metabolic imbalances. The regulation of transaminases involves feedback mechanisms, hormonal signals, and substrate availability, ensuring that amino acid metabolism remains balanced in response to physiological demands.