4.5. Surface Plasmon Resonance Imaging

All the assays and analyses were performed by Plexera LLC. The binding activity was measured by surface plasmon resonance imaging (SPRi) using a PlexArray HT system (Plexera LLC). The FDA1018 drug library chip consists of an array of 1018 U.S. FDA-approved drugs were ultraviolet-linked on the surface of a chip [28,29] and used for screening of compounds that bind to the HBx protein. Phosphate-buffered saline was used for a running buffer and 10 mM glycine hydrochloride (pH 2.0) for a regeneration buffer. 25, 50, or 100 nM of GST-HBx protein were injected on the chip surface at a flow rate of 2 ml/sec in order, and the SPRi signal was measured at 25 °C. FK506-binding protein 12 (FKBP12) was used for a positive control (Supplementary Figure S1). The data were analyzed by Plexera Data Analysis Software based on Langmuir adsorption isotherm, and determination of the dissociation constant, dissociation rate constant, and association rate constant was carried out.