The 10-12 kD aspartic protease of human immunodeficiency virus-1 (HIV-1), active only when it forms a homodimer, is required for the post-translational cleavage of the precursor polyproteins, Gag, Gag-Pol, Pol, and Nef. Since the cleavages of precursors are essential for the maturation of HIV infectious particles, this protease is one of the key targets for developing anti-AIDS drugs. The recombinant HIV-1 protease (wild type, NCBI accession: NC_001802) contains the 99 amino acid sequence reported by Schneider, et al., with 6x His-tag at its C-terminal. 50-100 ng of HIV-1 protease is sufficient for FRET-based activity assays (SensoLyte® 490 and 520 HIV Protease Assay Kits, AnaSpec Cat#71127, 71147) in high throughput drug screening.