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Figure 6.
Figure 6. The CD corner in deoxyMb at pH 4 (white), pH 5 (yellow) and pH 6 (red). Phe46 moves to the left in the
Figure at pH 4, increasing its distance to His64. N
d
of His48 hydrogen bonds to the carbonyl oxygen atom of Arg45
at pH 4, which may be the cause of the large displacement of these two residues. The rotation of the terminal atoms
of the side-chain of Arg45 at pH 4 disrupts the hydrogen-bond lattice. The heme-6-propionate group is in a new
conformation at pH 4, probably due to the loss of its hydrogen bond with Arg45. The =2Fo - Fc = electron density map
is contoured at 1.5 standard deviations above the average density of the map for deoxyMb at pH 4.
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