Fig. 2.

Plots representing the frequency (i.e., sequence counts) of the 4,000 library members before selection, after selection on empty resin, and after selection on streptavidin resin, as revealed by high-throughput 454 sequencing. The chemical structures of some of the most relevant straptavidin binders are indicated. The building blocks used in the 2 synthetic steps are indicated in green and red, respectively, together with the respective identification number. A known streptavidin binder (desthiobiotin) had been mixed with the library at low concentration before the selections serving as positive control.