Figure 5. Detachment force of antibodies.

Panel A shows the force-extension curve of a P-fimbria in the presence of anti-PapA antibodies. The force peaks (the parts of the force curve above the level of the unwinding force indicated with a red dashed line) represent the rise attributed to the force needed to disrupt an antibody-PapA interaction. The subsequent drop represents shaft unwinding after this disruption, which leads either to a plateau of continued unwinding or another rise in force due to another antibody-PapA interaction. The inset shows a detailed unwinding curve with small force peaks appearing above the level of the unwinding force. Panel B shows a kernel density estimate curve (bandwidth of 3.1) of the detachment forces during the unwinding process with a peak at 7.5 pN (n = 120).