hiv-1 protease saquinavir interaction - 3d model jaroddevos a2f3e06 stands human immunodeficiency virus causes immune system fail creates place infections cancers thrive due lack security enzyme which cleaves viral polyprotein precursors functional proteins infectious mimics cut hiv therefore blocking maturation inhibits preventing cleavage gag-po then immature molecules can no longer carry out their function not anymore hydroxyl group inhibitor interacts carboxyl active site asp 25 asp25 via hydrogen bonding between two