Background: The ribose-binding protein (RBP) from Escherichia coli is one of the representative structures of the periplastic binding proteins.Biological responses are typically mediated by ligand-induecd conformational changes in which the ribose binding event is coupled to a hinge-bending motion that brings together two domains in a closed form.The RBP has been crystallized in the open (PDB ID: 1URP) and the closed conformation (PDB ID: 2DRI) and the structures differ by a 41.3° rotation of the N-terminal domain relative to the C-terminal domain.