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. Author manuscript; available in PMC: 2009 Dec 1.
Published in final edited form as: J Immunol. 2009 Jun 1;182(11):7009–7018. doi: 10.4049/jimmunol.0804031

FIGURE 4.

FIGURE 4

Summary figure of relative affinities of rH19-20 wildtype and mutant proteins for C3b and heparin, and of complement functional cell-based assays. The salt concentration (mM NaCl) at which the rH19-20 wildtype or mutant proteins eluted from the heparin affinity column are graphed on the x-axis. The relative affinity of the mutants versus the wildtype (WT) protein for C3b is graphed on the y-axis using the formula: relative affinity = [(Kd of WT rH19-20) / (Kd of each rH19-20 mutant)]. The average of the Kd values obtained on the C3b-coated CM5 and SA sensor chips were used. The higher values represent higher affinity for each ligand, while lower values represent the opposite. The symbols that represent each mutant depend on their % of remaining wildtype activity in the cell-based assay that measured the ability of the mutants to inhibit fH binding to C3b-coated host-like cells (Fig. 5A). These values are in agreement with the results obtained in the EH lysis assay (Fig. 6).