FIGURE 2.

Phage ELISA results of variants identified from the cysteine library. Binding at pH 6.0 (A₄₅₀) is plotted against the ratio of pH 6.0 over pH 7.4 binding. High pH 6.0 A₄₅₀ values and a high pH 6.0/7.4 ratio suggest high affinity and pH-dependent binding, respectively. N3E-YTE (red) is a high affinity, pH-independent variant that shows a high A₄₅₀ reading at pH 6.0 yet a low pH 6.0/7.4 binding ratio. Sequences (residues 432–437) are shown for selected clones. All variants contain the YTE mutation (M252Y/S254T/T256E).