Aspartate aminotransferase (AST) is an important enzyme that is involved in amino acid metabolism and energy production. This enzyme catalyzes the transfer of an amino group from aspartate to α-ketoglutarate, producing oxaloacetate and glutamate. AST is found in a variety of tissues throughout the body, including the liver, heart, skeletal muscle, and kidneys. Because AST is released into the bloodstream when cells are damaged, it is a clinically significant biomarker used to evaluate tissue injury. Elevated AST levels are commonly associated with liver diseases, such as hepatitis and cirrhosis, as well as heart and muscle damage.
 
Signosis' AST assay kit measures the activity of AST by detecting its ability to transfer an amino group from L-aspartate to alpha-ketoglutarate. This reaction produces glutamate, which is quantified by another enzyme reaction. Glutamate is oxidized by glutamate oxidase to form a glutamate byproduct and hydrogen peroxide. Then, the glutamate level, which is proportional to AST activity in the sample, is determined by quantifying the hydrogen peroxide generated by the enzyme reaction with a fluorogenic probe that can be measured with a spectrophotometer.