is about half maximal effective concentration (EC50) equilibrium dissociation constant (KD) equilibrium dissociation constant (KD) approximated by EC50 Assay Development: Fundamentals and Practices, By Ge Wu, page 74 A measurement of an EC50 value under specific assay conditions approximates KD, namely the binding reaction is at an equilibrium, and the concentration of the receptor must be much less than the KD for the ligand. equilibrium dissociation constant (KD) approximated by EC50 PERSON: Bjoern Peters, Randi Vita binding EC50 binding datum metadata complete