The normalized intersurface force (F c /R) was measured when first bringing the protein and ligand surfaces into contact and again upon separating them. The normalized force F c /R is determined as a function of the separation distance D. The adhesion was then measured during surface separation. In these measurements, adhesion was measured after 8 min in contact. Prior studies of DC-SIGN showed that adhesion to fluid neoglycolipid membranes increases with time up to a limiting value, due to the lateral diffusion of glycan ligands and corresponding increase in number of CRDÀglycan bonds. 18 Because the lateral lipid diffusion and lipid density are identical for all samples in this study and in the prior measurements, differences in adhesion energies measured at identical contact times would therefore reflect functional differences between the different length variants.