title: Ligand binding and self-association cooperativity of β-lactoglobulin.
abstract: Unlike most small globular proteins, lipocalins lack a compact hydrophobic core. Instead, they present a large central cavity that functions as the primary binding site for hydrophobic molecules. Not surprisingly, these proteins typically exhibit complex structural dynamics in solution, which is intricately modified by intermolecular recognition events. Although many lipocalins are monomeric, an increasing number of them have been proven to form oligomers. The coupling effects between self-association and ligand binding in these proteins are largely unknown. To address this issue, we have calorimetrically characterized the recognition of dodecyl sulfate by bovine β-lactoglobulin, which forms weak homodimers at neutral pH. A thermodynamic analysis based on coupled-equilibria revealed that dimerization exerts disparate effects on the ligand-binding capacity of β-lactoglobulin. Protein dimerization decreases ligand affinity (or, reciprocally, ligand binding promotes dimer dissociation). The two subunits in the dimer exhibit a positive, entropically driven cooperativity. To investigate the structural determinants of the interaction, the crystal structure of β-lactoglobulin bound to dodecyl sulfate was solved at 1.64 Å resolution.
authors: Instituto de Química Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, México, DF 04630, México.
authors: Gabriel
authors: G
authors: Gutiérrez-Magdaleno
authors: Martiniano
authors: M
authors: Bello
authors: M Carmen
authors: MC
authors: Portillo-Téllez
authors: Adela
authors: A
authors: Rodríguez-Romero
authors: Enrique
authors: E
authors: García-Hernández
mesh_terms: D000818:Animals; D001665:Binding Sites; D002417:Cattle; D018360:Crystallography, X-Ray; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D007782:Lactoglobulins / Q000737:chemistry*; D008024:Ligands; D056004:Molecular Dynamics Simulation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D055503:Protein Multimerization; D021122:Protein Subunits / Q000737:chemistry*; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D007782:Lactoglobulins; D008024:Ligands; D021122:Protein Subunits; D012967:Sodium Dodecyl Sulfate; C028913:dodecyl sulfate