As soluble analytes, serial dilutions of polyanions were subsequently injected for 150 s, followed by a dissociation time of 600 s and a 30 s injection of 2 M NaCl to regenerate the surface. All SPR measurements were conducted in standard HBS-EP buffer (150 mM NaCl, 10 mM HEPES, 3 mM EDTA, 0,05% P20, pH 7.4). The chemicals NaCl, HEPES and EDTA were purchased from Carl Roth. The binding affinities were determined by using the BIAcore evaluation software version 4.0 using a 1:1 kinetic fit. The reference lane was left unmodified.