Figure 3 - full size

 

Figure 3.
Figure 3. The active site. a, The inhibitor Neu5Ac2en bound in the active site of the hexagonal crystal form. b, The same active site as observed in the ligand-free pH 4.6 orthorhombic crystal structure. c, The -anomer of sialic acid bound in the active site of the pH 4.6 orthorhombic crystal form, showing hydrogen bonding interactions (dotted lines). Water molecules are labeled W.

The above figure is reprinted by permission from Macmillan Publishers Ltd: Nat Struct Biol (2000, 7, 1068-1074) copyright 2000.