(A) Michaelis–Menten plot of the l-Ser β-elimination catalyzed by mouse SR. K_m and k_cat values for the l-Ser dehydration were determined to be 3.5 ± 0.4 mM and 97 ± 4 min⁻¹, respectively. Data were represented as means ± SD (error bars) of three independent experiments. (B) The Lineweaver–Burk plot of the l-Ser β-elimination reaction on inhibitor l-β-EHAsn concentration (0, 50, 100, 200 µM). The l-Ser β-elimination activity was inhibited by l-β-EHAsn with the K_i value of 40 ± 6 µM, which was estimated by global fitting to a mixed model inhibition equation using GraphPad Prism software α value of 19, R² = 0.98). Note that the data was also well fitted to a competitive inhibition equation (R² = 0.98). Reactions were carried out as described in Materials and Methods. Each data point represents mean of two independent experiments.