Fig. 3: Increasing temperature modulates substrate diffusion.
From: Probing the modulation of enzyme kinetics by multi-temperature, time-resolved serial crystallography
CTX-M-14 active site, 3 s after reaction initiation at 20 °C, 30 °C, and 37 °C; a 2Fo − Fc density shown at RMSD levels from 1.0–3.5, strongest density is shown in red; b 2Fo − Fc absolute value electron number (END) maps shown at 0.7 e−/ Å3; c,d) Fo − Fo difference electron density (DED) maps shown at 2.7 ± RMSD. c overview of the ligand density; d close-up of the catalytic Ser70. The piperacillin ligand is shown in the conformation of the covalent intermediate (blue) and the hydrolysis product (yellow), relevant CTX-M-14 active site residues are shown in grey, waters are omitted for clarity. All panels demonstrate the direct correlation between substrate diffusion and temperature as the electron density around the ligand increases relative to lower temperature. However, the DED maps also illustrate the change in relative occupancy, i.e., the concomitant conformational changes upon substrate hydrolysis.
