1. Crystal structures of influenza virus hemagglutinin in complex with high-affinity receptor 
Stanley J Watowich, John J Skehel, Don C Wiley 
Structure 
Volume 2, Issue 8, Pages (August 1994)
DOI: /S (00)

2. Figure 1 Chemical structures of high-affinity NeuAc analogs.
Structure 1994 2, DOI: ( /S (00) )

3. Figure 1 Chemical structures of high-affinity NeuAc analogs.
Structure 1994 2, DOI: ( /S (00) )

4. Figure 2
Stereoview of difference electron density maps for ligands bound to the receptor binding site of BHA (Cα trace is colored yellow). Phases calculated from 10 cycles of three-fold averaged solvent-flattened FoBHA/ligand− Fcmaps. (a) Three-fold averaged FoBHA/NeuAc2N6−FoBHA difference electron density map calculated at 2.2å resolution and contoured at 3σ for BHA in complex with NeuAc2N6. (b) Three-fold averaged FoBHA/NeuAc2N4−Fc difference electron density map calculated at 3.0å resolution and contoured at 1.0σ for BHA in complex with NeuAc2N4. (c) Three-fold averaged FoBHA/NeuAc4D−FoBHA difference electron density map calculated at 2.6å resolution and contoured at 3σ for BHA in complex with NeuAc4D. (d) Three-fold averaged FoBHA/G(4,4)NeuAc−FoBHA difference electron density map calculated at 2.6å resolution and contoured at 3σ for BHA in complex with G(4,4)NeuAc. (Figures generated using O [31].)
Structure 1994 2, DOI: ( /S (00) )

5. Figure 2
Stereoview of difference electron density maps for ligands bound to the receptor binding site of BHA (Cα trace is colored yellow). Phases calculated from 10 cycles of three-fold averaged solvent-flattened FoBHA/ligand− Fcmaps. (a) Three-fold averaged FoBHA/NeuAc2N6−FoBHA difference electron density map calculated at 2.2å resolution and contoured at 3σ for BHA in complex with NeuAc2N6. (b) Three-fold averaged FoBHA/NeuAc2N4−Fc difference electron density map calculated at 3.0å resolution and contoured at 1.0σ for BHA in complex with NeuAc2N4. (c) Three-fold averaged FoBHA/NeuAc4D−FoBHA difference electron density map calculated at 2.6å resolution and contoured at 3σ for BHA in complex with NeuAc4D. (d) Three-fold averaged FoBHA/G(4,4)NeuAc−FoBHA difference electron density map calculated at 2.6å resolution and contoured at 3σ for BHA in complex with G(4,4)NeuAc. (Figures generated using O [31].)
Structure 1994 2, DOI: ( /S (00) )

6. Figure 2
Stereoview of difference electron density maps for ligands bound to the receptor binding site of BHA (Cα trace is colored yellow). Phases calculated from 10 cycles of three-fold averaged solvent-flattened FoBHA/ligand− Fcmaps. (a) Three-fold averaged FoBHA/NeuAc2N6−FoBHA difference electron density map calculated at 2.2å resolution and contoured at 3σ for BHA in complex with NeuAc2N6. (b) Three-fold averaged FoBHA/NeuAc2N4−Fc difference electron density map calculated at 3.0å resolution and contoured at 1.0σ for BHA in complex with NeuAc2N4. (c) Three-fold averaged FoBHA/NeuAc4D−FoBHA difference electron density map calculated at 2.6å resolution and contoured at 3σ for BHA in complex with NeuAc4D. (d) Three-fold averaged FoBHA/G(4,4)NeuAc−FoBHA difference electron density map calculated at 2.6å resolution and contoured at 3σ for BHA in complex with G(4,4)NeuAc. (Figures generated using O [31].)
Structure 1994 2, DOI: ( /S (00) )

7. Figure 2
Stereoview of difference electron density maps for ligands bound to the receptor binding site of BHA (Cα trace is colored yellow). Phases calculated from 10 cycles of three-fold averaged solvent-flattened FoBHA/ligand− Fcmaps. (a) Three-fold averaged FoBHA/NeuAc2N6−FoBHA difference electron density map calculated at 2.2å resolution and contoured at 3σ for BHA in complex with NeuAc2N6. (b) Three-fold averaged FoBHA/NeuAc2N4−Fc difference electron density map calculated at 3.0å resolution and contoured at 1.0σ for BHA in complex with NeuAc2N4. (c) Three-fold averaged FoBHA/NeuAc4D−FoBHA difference electron density map calculated at 2.6å resolution and contoured at 3σ for BHA in complex with NeuAc4D. (d) Three-fold averaged FoBHA/G(4,4)NeuAc−FoBHA difference electron density map calculated at 2.6å resolution and contoured at 3σ for BHA in complex with G(4,4)NeuAc. (Figures generated using O [31].)
Structure 1994 2, DOI: ( /S (00) )

8. Figure 3
Stereoview of the molecular surface [36] overlaying residues of the extended receptor binding site of BHA. Apolar and polar regions of the molecular surface are colored white and cyan, respectively. The molecular surface was generated using a probe of 1.4å radius. Nitrogen, oxygen and sulfur atoms are colored blue, red and green, respectively. Carbon atoms of the protein are colored white. (a) Superposition of NeuAc2N6 (carbon atoms colored yellow) and NeuAc2N4 (carbon atoms colored purple) ligands bound to the BHA surface. (b) NeuAc4D (carbon atoms colored yellow) ligand bound to the BHA surface. (c) G(4,4)NeuAc (carbon atoms colored yellow) bound to the BHA surface. Residues in and around the binding site are labeled. (Figures generated using O [31].)
Structure 1994 2, DOI: ( /S (00) )

9. Figure 3
Stereoview of the molecular surface [36] overlaying residues of the extended receptor binding site of BHA. Apolar and polar regions of the molecular surface are colored white and cyan, respectively. The molecular surface was generated using a probe of 1.4å radius. Nitrogen, oxygen and sulfur atoms are colored blue, red and green, respectively. Carbon atoms of the protein are colored white. (a) Superposition of NeuAc2N6 (carbon atoms colored yellow) and NeuAc2N4 (carbon atoms colored purple) ligands bound to the BHA surface. (b) NeuAc4D (carbon atoms colored yellow) ligand bound to the BHA surface. (c) G(4,4)NeuAc (carbon atoms colored yellow) bound to the BHA surface. Residues in and around the binding site are labeled. (Figures generated using O [31].)
Structure 1994 2, DOI: ( /S (00) )

10. Figure 3
Stereoview of the molecular surface [36] overlaying residues of the extended receptor binding site of BHA. Apolar and polar regions of the molecular surface are colored white and cyan, respectively. The molecular surface was generated using a probe of 1.4å radius. Nitrogen, oxygen and sulfur atoms are colored blue, red and green, respectively. Carbon atoms of the protein are colored white. (a) Superposition of NeuAc2N6 (carbon atoms colored yellow) and NeuAc2N4 (carbon atoms colored purple) ligands bound to the BHA surface. (b) NeuAc4D (carbon atoms colored yellow) ligand bound to the BHA surface. (c) G(4,4)NeuAc (carbon atoms colored yellow) bound to the BHA surface. Residues in and around the binding site are labeled. (Figures generated using O [31].)
Structure 1994 2, DOI: ( /S (00) )

11. Figure 4
Details of the hydrogen-bonding contacts between the NeuAc moiety of sialic acid analogs (yellow) and residues forming the receptor binding site of BHA (gray). Hydrogen-bonds are represented by dashed lines. (Figure generated using MOLSCRIPT [36].)
Structure 1994 2, DOI: ( /S (00) )