Further characterization of the binding of heparin to granulocyte colony‐stimulating factor: Importance of sulfate groups

Heparin mediates fundamental biological mechanisms through interaction with proteins. Previously, we have shown that standard heparin binds to granulocyte colony‐stimulating factor (G‐CSF) with an affinity of 4.8×10 5  M −1 . To further study the structural features in heparin that are responsible for this interaction, we studied the bindings of G‐CSF and N ‐desulfated and 2,3‐ O ‐desulfated heparin by CZE. Results showed that the N ‐desulfated heparin had a similar affinity for G‐CSF ((5.4 ± 0.9)×10 5  M −1 ), but the 2,3‐ O ‐desulfated heparin had a 1000‐fold lower affinity ((3.4 ± 1.2)×10 2  M −1 ) in comparison to standard heparin. The results showed that 2,3‐ O ‐sulfate groups are more important than N ‐sulfate groups in heparin–G‐CSF interaction.