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Figure 3.
Figure 3. Comparison of the PfuCP/BsuCP active sites with ACE2
in the open and closed conformations. Ribbons diagram of protein
with side chains of key active site residues as stick drawings.
The metal ion is shown as a green sphere and its bonds to its
ligating residues are shown in stick. (A) PfuCP (PDB ID: 1KA4)
active site in open conformation with ribbons and carbons
colored in pink remaining elements in CPK. For this figure, the
ring of His A411 of PfuCP was rotated by 180° to be
consistent with the higher resolution TthCP structure and the
orientation of the conserved residue in the BsuCP structure. (B)
BsuCP active site in closed conformation with bound phosphate
ion with ribbons colored in cyan. (C) ACE2 (PDB ID: 1R42) active
site in open conformation in absence of bound substrate with
ribbons colored in yellow.[31] (D) ACE2 (PDB ID: 1R4L) active
site in closed conformation with ribbons colored in yellow and
carbons of bound MLN-4760 inhibitor colored in cyan and the
remaining atoms in CPK.[31] For panels (C) and (D), the ring of
His A505 was rotated by 180° to allow formation of a
hydrogen bond between its NE2 ring nitrogen and the Tyr A515
oxygen. The presence of this potential hydrogen bond was
predicted from their contact distance (  2.7
Å) in the 1R4L structure. This distance is long 3.3
Å in the 1R4L structure, but its His A505 was flipped as
well for consistency.
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