European Journal of Biochemistry vol:65 issue:1 pages:271-4
Glutamine transaminase, highly purified from rat brain, was studied. In the first series of experiments, the kinetics of the transamination reaction between 2-oxoglutaramate and phenylalanine were examined in order to determine the type of reaction mechanism. This proved to be of the ping-pont type, as can be expected for a transamination. The specificity of the enzyme for various amino acids and 2-oxo acids was then studied in detail. The most active substrates were glutamine, methionine and ethionine as amino-group donors, and phenylpyruvate, glyoxalate and 2-oxo-4-methiobutyrate as amino-group acceptors. For these and several other substrates, the kinetic constants, V and Km, were determined.