(121d) Fractal Analysis of Interleukin Binding and Dissociation Kinetics on Biosensor Surfaces

A fractal analysis is presented for the binding and dissociation of interleukin (wtIL5:IL5R) complex in solution to soluble c immobilized on a Biacore optical biosensor surface (Scibek et al. 2002). The fractal dimension value provides a quantitative measure of the degree of heterogeneity that exists on the sensor chip surface for the wtIL5:IL5R complex-soluble c ectodomain interaction. The degree of heterogeneity for the binding and the dissociation phases is, in general, different. Both types of examples are presented wherein either a single- or a dual-fractal analysis is required to describe the binding and/or dissociation kinetics. The dual-fractal analysis is used only when the single-fractal analysis did not provide an adequate fit (sum of least squares less than 0.98). This was done by regression provided by Quattro Pro 8.0 (Corel Quattro Pro, 1997). The binding rate coefficients and the affinity values are very sensitive to the degree of heterogeneity present on the sensor chip surface.