Monitoring ΔK122 PNT generation over time. SEC analysis (10 nm pore size) of 1 mg·mL-1 ΔK122 (blue) incubated with MPD in oligomerization buffer for 3 hours (brown), 24 hours (red) or 72 hours (green). The peak associated with ΔK122 (Peak 1) decreased over time with the appearance and increase in height of peaks associated with higher molecular weight species (Peaks 2 and 3). The relative areas of these peaks were integrated (inset table) to assess PNT oligomerization over time. The peaks were further characterized by MALS and TEM (Figure 3; Table 1) and identified as pilin-derived nanofibrils (Peak 2) and PNTs (Peak 3).