title: Local conformational fluctuations can modulate the coupling between proton binding and global structural transitions in proteins.
abstract: Local conformational fluctuations in proteins can affect the coupling between ligand binding and global structural transitions. This finding was established by monitoring quantitatively how the population distribution in the ensemble of microstates of staphylococcal nuclease was affected by proton binding. Analysis of acid unfolding and proton-binding data with an ensemble-based model suggests that local fluctuations: (i) can be effective modulators of ligand-binding affinities, (ii) are important determinants of the cooperativity of ligand-driven global structural transitions, and (iii) are well represented thermodynamically as local unfolding processes. These studies illustrate how an ensemble-based description of proteins can be used to describe quantitatively the interdependence of local conformational fluctuations, ligand-binding processes, and global structural transitions. This level of understanding of the relationship between conformation, energy, and dynamics is required for a detailed mechanistic understanding of allostery, cooperativity, and other complex functional and regulatory properties of macromolecules.
authors.affiliation: Department of Human Biological Chemistry and Genetics, University of Texas Medical Branch, Galveston, TX 77555, USA.
authors.forename: Steven T
authors.initials: ST
authors.lastname: Whitten
authors.forename: Bertrand
authors.initials: B
authors.lastname: García-Moreno E
authors.forename: Vincent J
authors.initials: VJ
authors.lastname: Hilser
mesh_terms: D001665:Binding Sites; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D008836:Micrococcal Nuclease / Q000737:chemistry; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D011522:Protons; D055672:Static Electricity; D013816:Thermodynamics
chemical_list: D008024:Ligands; D011522:Protons; D008836:Micrococcal Nuclease