FIGURE 2.

Assembly and dissociation of C3bB(Mg²⁺) on a C3b-coated biosensor surface. A, C3b (1860 response units (RU)) was covalently attached to a biosensor surface and treated for 90 s (indicated by the bar above the profiles) with 5 μg/ml wild-type plasma-derived native factor B, recombinant factor B, or factor B R234A in Mg²⁺ HEPES buffer followed by buffer alone. The resulting profiles were aligned at t = 0. The peak of the R234A profile represents complexes formed with 17% of the surface-bound C3b. Residual C3bB complexes were dissociated with EDTA HEPES buffer between factor B treatments. B, C3b-coated biosensor surface in A was treated as above with 5 μg/ml factor B R234N, factor B 233AAA, and recombinant factor B. C, C3b (2890 response units) was covalently attached to a biosensor surface and treated for 60 s with 2 μg/ml factor B R234A, factor B E446V, factor B E207A, or wild-type recombinant factor B followed by buffer alone. The resulting profiles were aligned at t = 0. The peak of the R234A profile represents complexes formed with 12% of the surface-bound C3b.