Hydrogen bonds between the central hydroxyl group of the two inhibitor conformations and the catalytic Asp25 and Asp25′ in the complex of (A) PR20/4410, (B) PR20/5010, (C) PR/4410, (D) PR/5010, and (E) PR20/darunavir. Inhibitor atoms of GRL-4410A, GRL-5010A, and darunavir are shown in ball and stick representation with magenta, cyan, and yellow carbons, respectively. PR20 is shown with green carbons and wild type PR with gray carbons. The PR20/4410 and PR20/5010 complexes are shown with 2Fo − Fc maps contoured at 1.7σ and 1.9σ, respectively.