A sensitive method for the assay of glutamine synthetase.

The method for the assay of glutamine synthetase (GlnS) relies on the gamma-glutamyl transferase reaction, i.e. the formation of glutamyl-gamma-hydroxamate from glutamine and hydroxylamine, and the chromatographic separation of the reaction product from the reactants. The method is not only simple and reliable, but also has a sensitivity comparable to those methods applying radioactively labelled substrates. This new procedure has been applied to the assay of GlnS in cultured rat cortical astroglial cells which have been treated with a homologous series of alpha, omega-bis-(dimethylamino)alkanes. Effects of these drugs on astroglial development are reported.