Figure 3
Comparison of the model structure of HPr from E. coli with the corresponding X-ray and NMR structures. A comparison of the modeled HPr homology structure with the structures experimentally determined by NMR spectroscopy (1HDN) and X-ray crystallography (1POH). The structures are shown in the same orientation as in Fig. 1 with the radius of the backbone splines indicating the RMSD of the Cαatom positions in the respective structures. (A) Overall good agreement between the model structure (yellow) and the X-ray structure (blue) is obtained. Deviations are mainly seen in loop regions and in the orientation of helices a and b. RMSD values for the Cαatom positions of the X-ray structure 1POH have been derived from the crystallographic B-factors, fB, using the Debye-Waller equation 
where isotropic displacement from the mean atom positions was assumed. (B) Comparison of the model (yellow) and the NMR structure (red). Deviations are seen in the same regions as before. (C) X-ray (blue) and NMR (red) structures superimpose well. Interestingly, deviations between them are mainly observed in regions where the two structures also diverge from the homology model.