S77 affects the formation, but not stability, of the alternative pathway
C3 convertase. A, S77 inhibits binding of factor B to C3b. C3b
was coated on microtiter plates. S77 or control Fab was added, followed by
addition of factor B. Binding of factor B to C3b was determined with
anti-factor B antibody and secondary antibodies conjugated to HRPO.
B, S77 Fab inhibits formation of C3 convertase. C3b was coated on
microtiter plates. S77 or control Fab was added, followed by addition of fB
and factor D. Binding of fBb to C3b was determined with anti-fB antibody and
secondary antibody conjugated to HRPO. C, S77 does not decay the C3
convertase. Microtiter plates were coated with C3b, incubated with factor B
and factor D followed by the addition of S77, sCR1 or control Fab. Factor Bb
was detected with goat anti-human factor B and donkey anti-goat antibody
conjugated to HRPO. Absorbance of the reaction product was read at 450 nm.
Data are expressed as mean ± S.D. of four repeats.