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-1 alpha 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-1 alpha and sIL-1R I was fast and specific, and the interaction response is dose-dependence of IL-1 alpha 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-1 alpha binding to sIL-1R I were determined from the plots of K-on versus the concentration of IL-1 alpha. For the interaction, k(ass) was 2.81 x 10(3) M-1 s(-1), K-diss was 2.52 x 10(-3) s(-1), and K-D was 8.97 x 10(-7) M. (c) 2005 Elsevier B.V. All rights reserved.