Two orthogonal peptide combinatorial libraries were screened to discover inhibitors of Tc80 protease, a novel target from Trypanosoma cruzi involved in host cell invasion. These libraries were composed of 15625 structurally diversified tripeptides, partitioned in 125 mixtures. The screening led to a low micromolar inhibitor which was actually an HF cleavage by-product H-Ipe-D-Tic-D-Glu (S-paratolyl)-OH. IC 50 values of several analogous ...