Figure 10

Docking of a cellotetraose acetate phthalate (CTAP) unit of CAP to the gp41 core structure. (A) Docking of CTAP on the gp41 core. The inner N-peptide coiled-coiled trimer is represented in green whereas the outer C-peptide helices are represented in yellow. Residues on the gp41 core interacting with CTAP (gray and red) are color-labeled. The brown residues are hydrophobic whereas blue residues are positively charged. One of the negatively charged groups from the phthalic acid moieties of CTAP docked near an R579 residue of the gp41 core. Two of the CTAP phenyl groups have hydrophobic contact with gp41 W571. The peptide segment 557–586 {[8, 39], corresponding to residues 550–571 in the X-ray crystal structure} antibodies to which are prevented by CAP from binding to gp41, is indicated in light blue in one of the three inner helices. (B) Electrostatic potential surface of the gp41 core created by the GRASP [31] program. The CTAP molecule docked near a relatively electropositive site on gp41. Most of the surface is highly electronegative.