Fig. 6: The key residue, K187, involved in enzyme catalysis.
From: Visualizing the enzyme mechanism of mevalonate diphosphate decarboxylase
a Partial sequence alignment results of the MDD family of proteins (see “Methods” section for details). Identical residues are highlighted in red. Homologous residues have their one-letter codes in red. Residues characterized to be functionally important among MDD proteins are marked by solid triangles17, 18, 40. Residues involved in substrate interaction are marked by empty stars and color-filled stars (red: S106; cyan: K187). The phosphate-binding loop and the β10-α4 loop are indicated with curved ribbons in magenta and cyan, respectively. b Relative enzyme activity of the K187A mutant and the wild-type MDDEF. The enzyme activities of MDDEF and K187A mutant of MDDEF were determined at saturating concentrations of two substrates (MVAPP = 200 μM; MgATP = 800 μM) and normalized by the means of wild-type MDD enzyme activity (n = 3 independent experiments). The means and the standard error (SEM) were derived from each triplicate. Source data are provided as a Source Data file. c ITC experiments of MDDEF and the K187A mutant. Left: the K187A mutant (100 μM) was titrated with ATPγS (3 mM). Right: the K187A mutant (100 μM) was pre-incubated with MVAPP (1 mM) and then titrated with ATPγS (2 mM). The thermodynamic parameters of each experiment are listed in Supplementary Table 6. The protein concentration was adjusted to 100 μM and all the protein and titrants were dissolved in the buffer containing 100 mM HEPES, pH 7, 100 mM KCl and 10 mM MgCl2. Error bars in b and c represent standard error of the mean (SEM).
