Abstract
This chapter introduces two formats using bio-layer interferometry competition assays to determine the solution K D values of weak glycan-protein interactions. This approach overcomes the challenge of determining weak interactions while minimizing the amount of reagents required. Accurate solution K D values aid in understanding the complex relationships between monomeric versus multimeric interactions and affinity versus avidity. The assays have been applied to a well-studied lectin (Erythrina crista-galli lectin) and influenza hemagglutinin (X-31). The solution K D values determined from this approach are in good agreement with previous reported literature values from isothermal titration calorimetry and NMR. Additionally, this approach appears robust and precise.