sentence: The general structure of the peptoid library used in this screening is shown in Fig. 1A.As a system to test the capacity of peptoids to inhibit the interaction of Ubc13 with Uev1 , we used the yeast-two hybrid assay , since it permits to readily determine the specificity of the inhibitory activities on a fully defined protein-protein interaction and , simultaneously , it constitutes a stringent filter for the bioavailability of active molecules .