Figure 3. Sorting of the affinity maturation libraries.

(a) Z_{VEGFR2_1matlib} (b) Z_{VEGFR2_2matlib} displayed on staphylococcal cells. The VEGFR2 binding signal (monitored by the binding of fluorescently labeled anti-Fc antibody to human VEGFR2/Fc) is represented on the Y axis and the surface expression level (monitored by fluorescently labeled HSA binding) is represented on the X axis. The dot plots show staphylococcal cell populations from the original unsorted library as well as cell populations isolated in the 1^st, 2^nd, 3^rd and 4^th selection round, respectively. For the 4^th selection round, dot plots are shown for selections including an off-rate experiment of 0 min, 30 min or 4.5 h.