Fig. 3
From: Molecular insights into the surface-specific arrangement of complement C5 convertase enzymes
Attachment of C3b with the thioester toward the surface is critical for C5 convertase activity. a Left, streptavidin beads with site-specifically biotinylated C3b molecules. Right, self-amplified C3b beads were generated by coating streptavidin beads with a low concentration of C3b-biotin after which FB, FD and C3 were added for five repeating incubations to allow natural deposition of C3b and formation of covalently associated C3b multimers (outlined in red). b C5 convertase activity on self-amplified and biotinylated C3b beads. Beads (containing equal levels of C3b) were incubated with FB, FD and C5 and C5a release was determined by calcium mobilization. c Random C3b beads were generated by coupling C3b-biotin onto tosyl-activated beads. d C5 convertase activity on random and biotinylated C3b beads. (b, d) Data of three independent experiments, presented as means ± standard deviation (SD)