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Figure 4.
Correlated breathing motion of the internal cavities in Mb.
(A and B) Structure of MbCO at 140 K before laser illumination
(magenta) (A) and after 750-min laser illumination (cyan) (B).
The electron densities of the CO molecules in the Xe cavities
are presented by using the 2F[o] − F[c] map (contoured at 0.3
e/Å^3). The surfaces of the internal cavities are shown by
the mesh. The cavities are also outlined by dotted lines. (C)
Amino acid residues lining the DP, Xe4, Xe2, Xe1, and Xe3
cavities. The color scheme is the same as that in A and B. The
outlines of the cavities are also superimposed. The movements of
amino acid residues between the cavities are shown by yellow
arrows, and those between the Xe3 cavity and solvent area are
shown by red arrows. The white arrows represent the ligand
migration pathway between the cavities. (D) Strain tensors
calculated by using 2 coordinates without laser illumination and
after 750-min laser illumination. The strain tensors are shown
with the maximum absolute eigenvalue, and the color of the
segment shows the magnitude of the eigenvalue (blue, −0.20;
green, 0, red, +0.20). The blue segments represent contraction,
and the red segments show expansion. (E) Schematic drawing of
the correlated ligand migration in a protein.
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