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 a nd 25 ' to 27 '. Up to now, the role of Thr26 and Thr26 ', and Gly27 and Gl y27 ', is unknown. It is hypothesized that strong hydrogen-bonding forces b etween the Thr26 and Thr26 ' residues stabilize the conformational state of the active site, and that the function of Gly27 and Gly27 ' is to accommod ate and bind a substrate in a position in which the catalytic Asp25 and Asp 25 ' carboxylate groups can attack the amide moiety of a substrate. (C) 200 1 John Wiley & Sons, Inc.