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Figure 5.
FIGURE 5. Ca^2^+ site in the EGF1 domain and location of
the Zn^2^+ sites and their linkage to the protease domain Ca^2^+
site in FVIIa. A, Ca^2+ site in the EGF1 domain. Electron
density (2F[obs] - F[calc]) contoured at 1  (gray) for Ca^2+
(magenta sphere) and two water molecules (red spheres) is shown.
Electron density contoured at 5 for Ca^2+ is shown in
blue. Note that in the presence of Ca^2+, Mg^2+ will not occupy
this site. All eight coordination ligands (black dashed lines)
are shown, and the residues labeled are those of the light chain
of FVIIa. B, location of the Zn^2+ sites and their linkage to
the protease domain Ca^2+ site. Electron density (2F[obs] -
F[calc]) contoured at 1 (gray) of Zn^2+ (cyan
spheres), Ca^2+ (magenta sphere), and water molecules (red
spheres) is shown. The electron density contoured at 3 for
Zn^2+ and Ca^2+ ions is shown in blue. Note the linkage between
the Zn^2+ sites and the Ca^2+ site. The metal ion coordination
to its ligands and H-bonds between water molecules is shown with
black dotted lines. Residue numbering used in the figure is that
of chymotrypsin.
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