The maturation of the AIDS virus requires a protease responsible for the cleavage of the gag polyprotein, the precursor of the core structural proteins. Thus, the protease is a promising target for the development of inhibitors therapeutically useful For the treatment of AIDS. The long term goal of this project is to aid in the design of HIV protease inhibitors by providing detailed structural information on HIV protease and protease/inhibitor complexes using NMR spectroscopy. Specifically, we plan to: 1) determine the NH exchange rates of bound peptide inhibitors and compare the amide N and H chemical shifts of the free and enzyme bound inhibitors using isotope-edited proton NMR techniques. 2) perform isotope-edited 2D NOE experiments of protease/inhibitor complexes using isotopically labeled inhibitors to obtain detailed information on inhibitor conformation and active site structure, 3) determine the complete three-dimensional structure of the protease and protease/inhibitor complexes using a variety of 2D and 30 NMR methods, 4) characterize the structure of protease mutants and other AIDS-associated retroviral proteases (e.g., HIV-2).