Binding of CCL2 wild-type to different carbohydrates and CCL2 variants to GlcNAcβ1,4[Fucα1,3]GlcNAcβ1-sp (sp: spacer O-[CH2]5COOH) measured with isothermal titration calorimetry and NMR spectroscopy at 299K.

and: not determined.bThe increased affinity of N91A might be an artifact caused by interaction of the artificial carbohydrate spacer O-(CH2)5-COOH with residue 91. Whereas the spacer might sterically clash with N91, Ala in this position could form favorable van-der-Waals interactions. In the case of natural N-glycans, where the reducing GlcNAc is linked to Asn of a glycoprotein projecting away from CCL2 (upper right corner of Figure 5D), Asn is likely to be favored at this position of CCL2 due to the potential formation of H-bonds.