Real time kinetic analysis of the interaction between interleukin-1α and soluble interleukin-1 receptor I using a resonant mirror biosensor

A novel method for real time kinetic analysis of the interaction between IL-1α and sIL-1R I is reported. sIL-1R I was immobilized on the biotin cuvette surface of the resonant mirror biosensor to set up the experimental model. Results obtained from the assay confirmed that biotinylated sIL-1R I was specifically immobilized on the avidin-coated biotin cuvette surface, the interaction between IL-1α and sIL-1R I was fast and specific, and the interaction response is dose-dependence of IL-1α in solution with a range of 150–2400 nM. The binding curve was fitted by FASTfit analysis, which fitted the monophasic association quite well, and the error did not exceed 0.4 arc seconds. Kinetic constants for IL-1α binding to sIL-1R I were determined from the plots of K on versus the concentration of IL-1α. For the interaction, k ass was 2.81 × 10 3 M −1 s −1, K diss was 2.52 × 10 −3 s −1, and K D was 8.97 × 10 −7 M.