Figure 5.

Proteolytic activity of Sat on complement proteins of the classical and the lectin activation pathways. Purified Sat and human complement proteins were incubated at 37°C for 5 and 24 h and the incubation products were analyzed by 10% SDS-PAGE, followed by immunodetection of the target proteins with specific complement antibodies (dilutions are indicated under each image) and peroxidase-conjugated anti-goat IgG (1:10,000). Reactivity was detected with the SuperSignal^® West Pico Enhanced Chemiluminescent Substrate kit (ThermoFisher Scientific). (A) Screening assays using 5 µg of Sat and 0.5 - 1.0 µg of complement proteins. (B) Inhibition assays using 0.5 - 1.0 µg of Sat or PMSF-inhibited Sat and 0.5 - 1.0 µg of target proteins. The molecular masses indicated in the images correspond to the chains of each protein after denaturation. Red asterisks indicate the cleavage products. Ladder: Precision Plus Protein Kaleidoscope Prestained Protein Standard (BioRad, USA).