Aspartate Aminotransferase (AST) is an enzyme found primarily in the liver, heart, and muscles. It plays a crucial role in amino acid metabolism by facilitating the transfer of an amino group from aspartate to alpha-ketoglutarate, producing oxaloacetate and glutamate. AST is commonly measured in blood tests to assess liver function and diagnose liver diseases, such as hepatitis or cirrhosis. Elevated levels of AST can indicate tissue damage, not only in the liver but also in the heart and muscles, making it a useful marker for various medical conditions.