Protease resistance profiles of wild-type and mutant V_HHs to the major GI proteases.

All VHH digestions were performed at 37°C for 1 h in the presence of 100 µg/mL protease. Resistance values were obtained by comparing the intensity of protease-digested VHHs relative to untreated controls using SDS-PAGE and imaging software. See Fig. 6A as an example. Values represent the mean ± SEM (n = 3). Data were incorporated into Fig. 6B and Fig. S5.