Figure 3.

Spike/heparan sulfate binding. ACE2 and the SARS-CoV-2 spike protein are displayed with yellow and cyan surfaces, respectively. The RBD is depicted with a transparent cyan surface. Spike protein and ACE2 are surrounded by a glycan shield generated by N-linked glycans illustrated with blue and dark gold sticks, respectively. HS is depicted with a per-atom-colored, stick representation: oxygen, red; hydrogen, white; nitrogen, blue; sulfur, yellow. Carbon atoms of N-acetyl-d-glucosamine residues are colored in blue, and carbon atoms of l-iduronic acid residues are colored in brown. a–b, Top and side view of the SARS-CoV-2 spike protein bound to HS. c, Electrostatic potential projected onto the RBD HS-binding patch with heparin bound. The surface is colored from red (negative) to blue (positive), representing electrostatic potential values of −4 k_bT/e to +4 k_bT/e. d, HS contributes to the formation of a ternary complex with the SARS-CoV-2 spike and ACE2.