Figure 8

Effect of four other amino acids on KAT activity of mouse brain crude protein extract. The reaction mixture consists of 5 mM kynurenine, 2 mM co-substrate (glyoxylate or α-ketoglutarate), 40 μM PLP, 5 mM other amino acid (putative inhibitor), 20 μg brain crude protein extract in 100 μL 100 mM phosphate buffer, pH 7.5 or 100 mM sodium borate buffer, pH 9. The mixture was incubated at 38°C for 2 h. The reaction was stopped by adding an equal volume of 0.8 M formic acid. Measurement of KYNA was performed by HPLC with fluorometric detection at Exc. 340 nm and Em. 398 nm. a) Results at pH 7.5 using α-ketoglutarate as a co-substrate, b) Results at pH 9 using glyoxylate as a co-substrate.