The active site of HIV-1 protease.

The active site of the homodimeric HIV-1 protease includes six amino acids (triads AspThrGly found in each monomer) in amino acid positions 25 to 27 and 25' to 27'. Up to now, the role of Thr26 and Thr26', and Gly27 and Gly27', is unknown. It is hypothesized that strong hydrogen-bonding forces between the Thr26 and Thr26' residues stabilize the conformational state of the active site, and that the function of Gly27 and Gly27' is to accommodate and bind a substrate in a position in which the catalytic Asp25 and Asp25' carboxylate groups can attack the amide moiety of a substrate. Copyright 2001 John Wiley & Sons, Inc. Med Res Rev, 21, No. 4, 348-353, 2001