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Figure 5.
Figure 5 Stereoviews of allosteric sites of effectors (a) RSR4,
(b) TB5-27 and (c) TB5-39. Protein and effector atoms are shown
as sticks and structural waters are red spheres. The Hb  [1]
subunit is light blue, the [2]
subunit is magenta, the  [1]
subunit is orange and the [2
]subunit is red. C atoms of allosteric effectors are yellow, O
atoms are red and N atoms are blue. Dashed black lines indicate
hydrogen bonds. For clarity, not all Hb residues lining the
allosteric binding sites are shown. Note, for visualization
purposes, and owing to secondary-site binding orientation
differences between RSR4 and the symmetrical effectors, Hb
residue labels and interaction distances for RSR4 in Fig. 5-(a)
are labeled on the opposite side of the dimer-dimer interface
with respect to labeled residues and interaction distances in
the TB5-27-Hb complex (Fig. 5-b) and the TB5-39-Hb complex (Fig.
5-c). For clarity of description, textual reference to RSR4-Hb
residue contacts follow dimer-dimer interface residue labeling
as pictured for TB5-27 and TB5-39. Importantly, the described
RSR4 interactions in the text correspond to equivalent
interactions made by this effector at its symmetry-related
binding sites and are the mirror image of the contacts labeled
in Fig. 5-(a).-.
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