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![[Figure 4]](ei5112fig4mag.jpg)
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Figure 4
MatchMaps results for isomorphous PTP1B data with a rotation artifact. Comparison of the apo (7rin) and TCS401-bound (7mm1) structures of protein tyrosine phosphatase 1B. (a) The apo (gray) and bound (blue) structural models overlay well, but differ by a slight rotation. The difference in the models is especially apparent in the boxed region [see panel (g)]. (b) Aligning the apo model (red) to the bound model (blue) reveals that the structures overlay even better than the original coordinates suggest [see panel (h)]. (c) and (d) Both the isomorphous map (c) and the MatchMaps map (d) are clearly able to show the bound ligand. The TCS401 ligand (gray sticks) is shown for clarity but was not included in the computation of either map. Positive difference density is shown as blue mesh. (e) and (f) Close-ups of residues 180–182. Similarly to panels (c) and (d), the change in loop equilibrium between open (red mesh, red sticks) and closed (blue mesh, blue sticks) is apparent in both maps. (g) and (h) Residues 22–25 are shown. Though these data sets meet the requirements for isomorphism, the refined protein models still differ by a slight rotation. (g) The isomorphous difference map recognizes the artifactual difference between 7mm1 (blue) and 7rin (gray) model locations, which manifests as strong difference signal. This artifact is comparable in magnitude to the `true' signal in panels (c) and (e). (h) MatchMaps internally aligns the data before subtraction and therefore avoids this artifact. The bound model after alignment to the apo model is shown in red. At ±2.5σ, there is no significant signal in the MatchMaps map for this region. |
![[Figure 4]](ei5112fig4.jpg)
 | JOURNAL OF APPLIED CRYSTALLOGRAPHY |
ISSN: 1600-5767
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