AST, or aspartate aminotransferase, is an enzyme primarily found in the liver, heart, and muscles, playing a crucial role in amino acid metabolism by facilitating the conversion of aspartate and α-ketoglutarate to oxaloacetate and glutamate. Its measurement is vital in clinical practice for diagnosing liver injury, myocardial infarction, and other conditions. Elevated AST levels can indicate liver disease, such as hepatitis, or muscle damage, necessitating further evaluation for underlying causes.