Fig. 2. Colorimetric assay with 2-(4-nitrophenyl)ethan-1-amine 5 as amine donor using substrates 1, 8–17: 5 (25 mM), amino acceptor 1, 8–17 (10 mM), PLP (0.5 mM), KPi buffer pH 7.5 (100 mM) and clarified cell extract (0.2–0.4 mg mL–1), 30 °C, 400 rpm, 18 h. Water was used as a negative control (N), and a red precipitate was indicative of activity. Assays were performed in duplicate.
