CCR2 chemokine binding to heparan sulfate by ESI FT‐ICR mass spectrometry

Chemokines are known to bind to glycosaminoglycans (GAGs), the long polysaccharide components of cell surface proteoglycans and the extracellular matrix (ECM). The predominant cell surface GAG is heparan sulfate (HS). However heparin is usually studied in place of HS in GAG binding assays. HS, while structurally related to heparin, is actually less sulfated, more acetylated, and more heterogenous in nature. We set out to characterize the noncovalent interactions of chemokines of the receptor CCR2 with octasaccharides generated from a HS digest. The analysis was performed using electrospray ionization (ESI) Fourier transform‐ ion cyclotron resonance mass spectrometry (FT‐ICR MS). Our data suggest that the CCR2 chemokines bind to highly sulfated HS oligosaccharides. Taken together with the heterogenous nature of intact HS, this suggests that in vivo these chemokines may be retained on specific highly sulfated loci.