Affinity, kinetics, and thermodynamics of E-selectin binding to E-selectinligand-1

E-selectin is an endothelial adhesion molecule, which mediates the tetherin g and rolling of leukocytes on vascular endothelium. It recognizes the glyc oprotein E-selectin ligand-1 (ESL-1) as a major binding partner on mouse my eloid cells. Using surface plasmon resonance, we measured the kinetics and affinity of binding of monomeric E-selectin to ESL-1 isolated from mouse bo ne marrow cells. E-selectin bound to ESL-1 with a fast dissociation rate co nstant of 4.6 s(-1) and a calculated association rate constant of 7.4 X 10( 4) M-1. s(-1). We determined a dissociation constant (K-d) of 62 muM, which resembles the affinity of L-selectin binding to glycosylation-dependent ce ll adhesion molecule-1. The affinity of the E-selectin-ESL-1 interaction di d not change significantly when the temperature was varied from 5 degreesC to 37 degreesC, indicating that the enthalpic contribution to the binding i s small at physiological temperatures, and that, in contrast to typical pro tein-carbohydrate interactions, binding is driven primarily by favorable en tropic changes. Interestingly, surface plasmon resonance experiments with r ecombinant ESL-1 from alpha1,3-fucosyltransferase IV-expressing Chinese ham ster ovary cells showed a very similar K-d of 66 muM, suggesting that this fucosyltransferase is sufficient to produce fully functional recombinant ES L-1. Following the recent description of the affinity and kinetics of the s electin-ligand pairs L-selectin-glycosylation-dependent cell adhesion molec ule-1 and P-selectin-P-selectin glycoprotein ligand-1, this is the first de termination of the parameters of E-selectin binding to one of its naturally occurring ligands.