Molecular mimicry of substrate oxygen atoms by water molecules in the beta-amylase active site.

ABSTRACT: Soybean beta-amylase (EC 3.2.1.2) has been crystallized both free and complexed with a variety of ligands. Four water molecules in the free-enzyme catalytic cleft form a multihydrogen-bond network with eight strategic residues involved in enzyme-ligand hydrogen bonds. We show here that the positions of these four water molecules are coincident with the positions of four potential oxygen atoms of the ligands within the complex. Some of these waters are displaced from the active site when the ligands bind to the enzyme. How many are displaced depends on the shape of the ligand. This means that when one of the four positions is not occupied by a ligand oxygen atom, the corresponding water remains. We studied the functional/structural role of these four waters and conclude that their presence

SUBMITTER: Pujadas G 

PROVIDER: S-EPMC2374084 | biostudies-literature | 2001 Aug

REPOSITORIES: biostudies-literature