Figure 2. Substrate specificity of several putative branched chain amino acid transaminases.

Reaction conditions: 10 mM α-ketoglutaric acid, 5 mM l-amino acid, 0.1 mM PLP, 0.5 mM NAD⁺, 1 U GDH (l-glutamate dehydrogenase) in 50 mM KPi, pH 8, with cell-free E. coli lysate containing different TAs (0.125 mg mL⁻¹ total lysate protein), following the formation of NADH at 340 nm and 30 °C. The reactions were performed in triplicate. The relative activities were compared to the activity with l-leucine (Table 1). Solid grey: CpuTA2, light grey: MgiTA2, darker grey dashed: RaqTA2. l-Nle = l-norleucine, l-Nva = l-norvaline.