title: Equilibria of oligomeric proteins under high pressure - A theoretical description.
abstract: High pressure methods have become a useful tool for studying protein structure and stability. Using them, various physico-chemical processes including protein unfolding, aggregation, oligomer dissociation or enzyme-activity decrease were studied on many different proteins. Oligomeric protein dissociation is a process that can perfectly utilize the potential of high-pressure techniques, as the high pressure shifts the equilibria to higher concentrations making them better observable by spectroscopic methods. This can be especially useful when the oligomeric form is highly stable at atmospheric pressure. These applications may be, however, hindered by less intensive experimental response as well as interference of the oligomerization equilibria with unfolding or aggregation of the subunits, but also by more complex theoretical description. In this study we develop mathematical models describing different kinds of oligomerization equilibria, both closed (equilibrium of monomer and the highest possible oligomer without any intermediates) and consecutive. Closed homooligomer equilibria are discussed for any oligomerization degree, while the more complex heterooligomer equilibria and the consecutive equilibria in both homo- and heterooligomers are taken into account only for dimers and trimers. In all the cases, fractions of all the relevant forms are evaluated as functions of pressure and concentration. Significant points (inflection points and extremes) of the resulting transition curves, that can be determined experimentally, are evaluated as functions of pressure and/or concentration. These functions can be further used in order to evaluate the thermodynamic parameters of the system, i.e. atmospheric-pressure equilibrium constants and volume changes of the individual steps of the oligomer-dissociation processes.
authors.affiliation: Tomas Bata University in Zlín, Faculty of Technology, Department of Physics and Materials Engineering, nám. T. G. Masaryka 5555, 76001 Zlín, Czechia; Charles University in Prague, Faculty of Science, Department of Biochemistry, Hlavova 2030, 12843 Prague 2, Czechia. Electronic address: ingr@ft.utb.cz.
authors.forename: Marek
authors.initials: M
authors.lastname: Ingr
authors.affiliation: Tomas Bata University in Zlín, Faculty of Technology, Department of Physics and Materials Engineering, nám. T. G. Masaryka 5555, 76001 Zlín, Czechia.
authors.forename: Eva
authors.initials: E
authors.lastname: Kutálková
authors.affiliation: Tomas Bata University in Zlín, Faculty of Technology, Department of Physics and Materials Engineering, nám. T. G. Masaryka 5555, 76001 Zlín, Czechia.
authors.forename: Josef
authors.initials: J
authors.lastname: Hrnčiřík
authors.affiliation: Université Montpellier, INRA UMR IATE, Biochimie et Technologie Alimentaires, cc023, Place Eugene Bataillon, 34095 Montpellier Cedex 05, France.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Lange
mesh_terms: D000465:Algorithms; D007700:Kinetics; D008956:Models, Chemical; D011312:Pressure; D066263:Protein Aggregation, Pathological; D055503:Protein Multimerization; D021122:Protein Subunits / Q000737:chemistry; D058767:Protein Unfolding; D011506:Proteins / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D021122:Protein Subunits; D011506:Proteins
keywords: Equilibrium; High pressure; Inflection point; Oligomeric protein; Theory