12-BROMODODECANOIC ACID BINDS INSIDE THE CALYX OF BOVINE BETA-LACTOGLOBULIN

The X-ray structure of bovine beta-lactoglobulin with the ligand 12-br omododecanoic acid as a model for fatty acids has been determined at a resolution of 2.23 Angstrom in the trigonal lattice Z form. The ligan d binds inside the calyx, resolving a long-standing controversy as to where fatty-acid like ligands bind. The carboxylate head group lies at the surface of the molecule, and the lid to the calyx is open at the pH of crystallization (pH 7.3), consistent with the conformation obser ved in ligand-free bovine B-lactoglobulin in lattice Z at pH 7.1 and p H 8.2. (C) 1998 Federation of European Biochemical Societies.