Assay Method Information

Assay Name:  SPR binding assay
Description:  All SPR measurements with compounds were performed using a Biacore 3000 (GE Healthcare) at 25° C. Biotinylated ASGPR was immobilized typically at 2000-3000 resonance units (Ru) using either SA sensor chips (GE Healthcare) or custom sensor chips with Neutravidin (Pierce Biochemical) immobilized by standard amine coupling to CM5 sensor chips (GE Healthcare). The running buffer was HBS (10 mM HEPES, 150 mM NaCl), 20 mM CaCl2, 0.01% p20, 3% DMSO or 50 mM tris, 150 mM NaCl, 50 mM CaCl2), 0.01% p20, 3% DMSO pH 7.5. Compounds were diluted into running buffer at a concentration of 900 uM and serially diluted 3 fold to 3.7 uM. Compound solutions were injected at 50 ul/min for 1 min followed by a 1 min dissociation in duplicate for each concentration. For the multimeric conjugates (dimers, trimers), the conjugates were diluted in running buffer to concentrations of 100 nM or 10 nM and serially diluted. Conjugates were injected for 2 min and off rates were detected for 300 or 600 sec. After completion of off phase data the compounds were displaced using an injection of 900 uM GalNAc returning the receptor surface to the free state. All data was processed using Scrubber2 (Biologic Software, Inc.) to zero, align, reference and correct for excluded volume effects. KDs were determined by fitting the steady state binding responses for the compounds and single conjugated molecules in Scrubber2. KD for multimeric conjugates showing kinetic responses were processed in Scrubber2 and fit in BiaEval (GE Healthcare) to extract the on and off rate parameters in order to calculate KD. Values reflect standard deviations from multiple experiments.
Affinity data for this assay
 

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