Figure 8.

GAG-binding to proteins: From “high selectivity” to “non-selectivity”,⁸⁸ a continuous spectrum of interactions intermediate cases exists. (a) The panel displays a system in which unique interactions between sulfate groups of heparin and basic residues of antithrombin result from a highly selective recognition. (b) The GAG–protein mode of interactions exhibits a “moderate selectivity” where several binding modes occur throughout the “chain polarity” in terms of the directionality of binding. (c) Illustrates a “plastic” type of interaction, where the GAG chain slides along the protein binding site while maintaining the directionality of the chain. (d) The structure on the right panel shows no preference for the protein’s GAG sequence, as the several binding poses are fully nonselective.