Oxaloacetate (OAA, HOOC-CO-CH₂-COOH) is a TCA cycle intermediate. It precedes citrate which is formed by the transfer of an acetyl group to OAA. OAA is formed by the deamidation of aspartate or condensation of CO2 with pyruvate or PEP. Since mammals do not possess the enzymatic machinery to form TCA cycle intermediates from acetyl CoA, OAA is one of the anaplerotic entry points via pyruvate and pyruvate carboxykinase. BioVision's Oxaloacetate Assay Kit provides a simple, sensitive and rapid means of quantifying OAA in a variety of samples. In the assay, OAA is converted to pyruvate which is utilized to convert a nearly colorless probe to an intensely colored (λmax= 570nm) and fluorescent (Ex/Em = 535/587nm) product. The Oxaloacetate Assay Kit can detect 0.1-10nmol (2-200 µM) of OAA.