Fig. 3From: Molecular cloning and characterization of a grapevine (Vitis vinifera L.) serotonin N-acetyltransferase (VvSNAT2) gene involved in plant defenseCharacterization of enzymatic activity of VvSNAT2. a–c Analysis of the enzymatic activity of VvSNAT2 at different pH (a), protein concentration (b) and temperature (c). d Determination of Km and Vmax values of VvSNAT2 using serotonin as a substrate. VvSNAT2 (1 μg) was incubated with variable substrate concentrations for 30 min at 45 °C. The expression of VvSNAT2 protein in transformed bacteria was induced by the addition of IPTG and 1 mM tryptamine for 12 h. The bacterial pellets were collected and used for the quantification of N-acetyltryptamine via HPLC. The Km and Vmax values were determined using Lineweaver–Burk plots. Data represent mean ± SD of triplicate experiments. Different letters indicate statistically significant differences at P < 0.05Back to article page