FIGURE 1.
(a) The monomer of SBA (PDB code 2sba) showing the disposition of the tryptophan residues. The residue numbers are indicated in boldface. (b) The types of residues present at the two-state interface of SBA tetramer. The figure clearly indicates that the interface is mainly made up of polar residues. The residues at the interface are marked by the ball-and-stick model. (Carbon is represented by black, oxygen by red, and nitrogen by blue spheres in the model.) The residues that line up the interface are 1–10, 163–173, and 183–193. (d) Numbers represent the residues that line up the canonical interface in SBA. (c) The residues at the non-canonical interface in SBA. The latter residues are not marked to avoid overcrowding; however, it is quite clear from the figure that this interface has a considerable number of polar residues.