Abstract

Memapsin 2 (β-secretase) is a membrane-associated aspartic protease involved in the production of β-amyloid peptide in Alzheimer's disease and is a major target for drug design. We determined the crystal structure of the protease domain of human memapsin 2 complexed to an eight-residue inhibitor at 1.9 angstrom resolution. The active site of memapsin 2 is more open and less hydrophobic than that of other human aspartic proteases. The subsite locations from S 4 to S 2 ′ are well defined. A kink of the inhibitor chain at P 2 ′ and the change of chain direction of P 3 ′ and P 4 ′ may be mimicked to provide inhibitor selectivity.