Figure 4. The atomic interaction details at the binding interface.
a, An overview of the binding interface. CD26 and RBD are shown in surface and cartoon representations, respectively, and are coloured as in Fig. 3. The carbohydrate moiety linked to CD26 N229 is shown as green sticks. The contacting sites (each allocated with an Arabic number 1–4) are further delineated in b–e for the amino acid interaction details. b, A strong polar-contact (H-bond and salt-bridge) network. c, d, The small patches of hydrophobic interactions. e, Contribution of the carbohydrate moiety. The residues involved are shown and labelled. NAG, N-acetyl-D-glucosamine; BMA, beta-D-mannose.