Surface plasmon resonance spectroscopy was performed using the BIAcore T100 system. TNF-FLAG was directly immobilized onto anti-FLAG-coated chips from culture supernatants. Experiments were carried out using serial dilutions of the indicated purified Fc-fusion proteins. Binding curves were analyzed using BIAcore T100 Evaluation software to fit the data and determine dissociation constants (Kd), assuming 1:1 binding.
