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. 2016 Sep 22;7:1511. doi: 10.3389/fmicb.2016.01511

FIGURE 3.

FIGURE 3

(A) Color development of the acetophenone-vanillin reaction with different acetophenone concentrations over time. Concentrations (from top to bottom): 10, 8, 6, 4, 2, 1, 0 mM acetophenone. Reaction conditions to simulate realistic assay conditions: 30 mM tert-butyl hydroperoxide, 10–0 mM acetophenone and formaldehyde, 0–10 mM α-methylstyrene, 1 mg/mL Escherichia coli BL21 (DE3) Gold lysate with overexpressed CupinX (a cupin protein without alkene cleavage activity) in 50 mM NaPi, pH 7.0, in a total volume of 150 μL. 40 μL of detection solution consisting of 5 M NaOH, 2.5% vanillin and 50% ethanol were added to start the color reaction. (B) Standard curve of acetophenone in the range of 1–10 mM (in a total volume of 150 μL in 50 mM NaPi, pH 7.0) detected with 40 μL of detection solution (2 M NaOH, 3.5% vanillin and 10% EtOH) for 30 min at room temperature. Absorption was measured at 450 nm.