Surface Plasmon Resonance of GPR4 polyclonal antibody (Product # PA5-70638). Purified polyclonal antibodies were immobilized on a Protein A/G coated Carterra LSA sensor chip at concentrations of 5, and 50 µg/mL in duplicate. Antibodies on the surface were exposed to interaction with peptides sequentially via microfluidic controlled flow at 333 nm peptide concentration for kinetic characterization of the binders for affinity and specificity, followed by curve fitting using the Kinetics software. Kd determinations for both concentrations were averaged and results and standard deviation are shown.