HPLC determination of α-ketoglutaramate [5-amino-2,5-dioxopentanoate] in biological samples.

α-Ketoglutaramate is an important glutamine metabolite in mammals, plants, and many bacteria. It is also a nicotine metabolite in certain bacteria. Previously published methods for the determination of α-ketoglutaramate in biological samples have considerable drawbacks. Here, we describe a relatively simple high-performance liquid chromatography (HPLC)-based method for measurement of α-ketoglutaramate in plasma and deproteinized tissues that overcomes these drawbacks. Concentrations of α-ketoglutaramate in normal rat liver, kidney, brain, and plasma were found to be approximately 216, 13, 6, and 19 μM, respectively. The HPLC method should be useful for studying the role of α-ketoglutaramate in eukaryotic glutamine metabolism and in bacterial nicotine metabolism.