A high-performance liquid chromatography assay for asparagine synthetase.

A highly sensitive method for assaying asparagine synthetase and its glutaminase activity is presented. The amino acids L-asparagine, L-aspartate, L-glutamate, and L-glutamine, are separated by derivatization with o-phthaldialdehyde followed by reversed-phase high-performance liquid chromatography on an Altex ultrasphere-ODS C18 column. The elution is isocratic and the mobile phase used is 50 mM sodium acetate buffer (pH 5.9) with 30% methanol. This assay can easily detect picomoles of asparagine, which may be difficult to do with the other assays that have been described.