Bioanalysis of N-acetyl-aspartyl-glutamate as a marker of glutamate carboxypeptidase II inhibition.
We report the characterization of two methods for the analysis of N-acetyl-aspartyl-glutamate (NAAG) in biological fluids. In the first method, NAAG concentrations were calculated based on differences between glutamate concentrations before and after NAAG hydrolysis with exogenous glutamate carboxypeptidase II (GCP II) using high-performance liquid chromatography (HPLC) followed by fluorescence detection. In the second method, NAAG levels were quantified directly using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Analyses of NAAG levels in human cerebrospinal fluid samples using either method gave similar results within experimental error, confirming the validity of the two independent measurements. These methods will be useful in future clinical trials to assess drug-induced GCP II inhibition in biological matrices.
Thomas
Ajit G
AG
Brain Science Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Rojas
Camilo J
CJ
Hill
Jeanette R
JR
Shaw
Michael
M
Slusher
Barbara S
BS
D015415:Biomarkers / Q000134:cerebrospinal fluid; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004151:Dipeptides / Q000134:cerebrospinal fluid*; D043425:Glutamate Carboxypeptidase II / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D053719:Tandem Mass Spectrometry / Q000379:methods*
D015415:Biomarkers; D004151:Dipeptides; C027172:isospaglumic acid; D043425:Glutamate Carboxypeptidase II