Water mobility, denaturation and the glass transition in proteins. 2012

David Porter, and Fritz Vollrath
Department of Zoology, University of Oxford, Oxford, UK. david.porter@zoo.ox.ac.uk

A quantitative mechanism is presented that links protein denaturation and the protein-water glass transition through an energy criterion for the onset of mobility of strong protein-water bonds. Differences in the zero point vibrational energy in the ordered and disordered bonded states allow direct prediction of the two transition temperatures. While the onset of water mobility induces the same change in heat capacity for both transitions, the order-disorder transition of denaturation also predicts the observed excess enthalpy gain. The kinetics of the water and protein components through the glass transition are predicted and compared with dielectric spectroscopy observations. The energetic approach provides a consistent mechanism for processes such as refolding and aggregation of proteins involved in protein maintenance and adaptability, as the conformational constraints of strong water-amide bonds are lost with increased molecular mobility. Moreover, we suggest that the ordered state of peptide-water bonds is induced at the point of protein synthesis and could play a key role in the function of proteins through the enhancement of electronic activity by ferroelectric domains in the protein hydration shell, which is lost upon denaturation.

UI MeSH Term Description Entries
D007700 Kinetics The rate dynamics in chemical or physical systems.
D008958 Models, Molecular Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures. Molecular Models,Model, Molecular,Molecular Model
D011489 Protein Denaturation Disruption of the non-covalent bonds and/or disulfide bonds responsible for maintaining the three-dimensional shape and activity of the native protein. Denaturation, Protein,Denaturations, Protein,Protein Denaturations
D011506 Proteins Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein. Gene Products, Protein,Gene Proteins,Protein,Protein Gene Products,Proteins, Gene
D003460 Crystallization The formation of crystalline substances from solutions or melts. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed) Crystalline Polymorphs,Polymorphism, Crystallization,Crystal Growth,Polymorphic Crystals,Crystal, Polymorphic,Crystalline Polymorph,Crystallization Polymorphism,Crystallization Polymorphisms,Crystals, Polymorphic,Growth, Crystal,Polymorph, Crystalline,Polymorphic Crystal,Polymorphisms, Crystallization,Polymorphs, Crystalline
D006860 Hydrogen Bonding A low-energy attractive force between hydrogen and another element. It plays a major role in determining the properties of water, proteins, and other compounds. Hydrogen Bonds,Bond, Hydrogen,Hydrogen Bond
D000465 Algorithms A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task. Algorithm
D012997 Solvents Liquids that dissolve other substances (solutes), generally solids, without any change in chemical composition, as, water containing sugar. (Grant & Hackh's Chemical Dictionary, 5th ed) Solvent
D013816 Thermodynamics A rigorously mathematical analysis of energy relationships (heat, work, temperature, and equilibrium). It describes systems whose states are determined by thermal parameters, such as temperature, in addition to mechanical and electromagnetic parameters. (From Hawley's Condensed Chemical Dictionary, 12th ed) Thermodynamic
D014867 Water A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed) Hydrogen Oxide

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