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Figure 4.
(a) Ribbon diagram of DBL3x overlayed on a semitransparent
electrostatic potential surface. Side chains of lysines and
arginines responsible for the positively charged region are
shown in red. Subdomain 1 (yellow), subdomain 2 (blue) and
subdomain 3 (red) are shown. For clarity, Lys1327 is not shown.
(b) Positively charged areas (blue) are located on the sides of
the binding area for the CSA oligosaccharide, shown in same
orientation as in a. Lysines and arginines with side chains
within 5 Å of the carbohydrate density are labeled (+,
yellow). Below the CSA binding site is a region of negatively
charged residues (red at arrow), which could prevent CSA from
occupying the deeper portions of the 'valley' between subdomains
2 and 3. (c) View of a CSA hexasaccharide model^39 (PDB 1C4S)
placed along the extra electron density seen in the crystals.
The hexasaccharide shown here is approximately 30 Å in
length and similar to the length of the observed electron
density. Lys1327 is shown.
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