view article
Figure 4
Electron density map analyses of avibactam (Avi) bound to CTX-M-15 microcrystals obtained through drop-on-fixed-target tr-SSX and tr-SFX (Tables S4 and S5). Tr-SSX maps for CTX-M-15 mixed with Avi (200 mM) for 2.6 s (a–f), collected using the Add and Revisit approach at I24 Diamond Light Source, are determined to 1.55 Å resolution. (a) 2mFo − DFc map of the active site of the CTX-M-15·Avi complex (radius: 1.5 Å, contour: 1σ); (b) mFo − DFc polder OMIT map (radius: 2.0 Å, contour: 3σ); (c) Fo2.6 s − FoApo isomorphous difference map (contour: 3σ; integrated density: 40.64 e−); (d) 2mFo − DFc map of the interleaved control (i.e. without ligand added; radius: 1.5 Å, contour: 1σ); (e) mFo − DFc polder OMIT map (radius: 2.0 Å, contour: 3σ); (f) FoControl − FoApo isomorphous difference map (contour: 3σ; integrated density: 1.71 e−). Tr-SFX maps for CTX-M-15 mixed with Avi for 80 ms (g–l), collected at 30 Hz using the Add and Collect approach at NCI PAL-XFEL are determined to 1.50 Å resolution. (g) 2mFo − DFc map of the active site of the CTX-M-15·Avi complex (radius: 1.5 Å, contour: 1σ); (h) mFo − DFc polder OMIT map (radius: 2.0 Å, contour: 3σ); (i) Fo80 ms − FoApo isomorphous difference map (contour: 3σ; 6.40 e−); (j) 2mFo − DFc map of the interleaved control (i.e. without ligand added) (radius: 1.5 Å, contour: 1σ); (k) mFo − DFc polder OMIT map of the interleaved control (radius: 2.0 Å, contour: 3σ); (l) FoControl− FoApo isomorphous difference map (contour: 3σ; integrated density 1.43 e−). Density colour guidelines: grey modelled density; blue positive density; red negative density.

IUCrJ
Volume 13| Part 4| July 2026|
ISSN: 2052-2525
https://doi.org/10.1107/S2052252526003489