The mAb 1C9 binds to C6 in free circulation and within the C5b6 complex with high affinity. SPR sensorgram shows the binding kinetics for C6 (A) and C5b6 (B) with immobilized 1C9 antibody. Data are shown as black lines, and the best fits of the data to a 1:1 binding model (antigen-binding fragment) are shown in red.