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.

High-pressure small-angle X-ray scattering cell for biological solutions and soft materials

“…The X-ray sample cells being implemented at CHESS are part of a larger toolkit being created by a US National Science Foundation supported Research Coordination Network (RCN) of over two dozen international collaborators interested in high-pressure biology. Other tools being worked on by RCN colleagues include HP-NMR (Peterson & Wand, 2005;Roche et al, 2019;Caro & Wand, 2018;Akasaka, 2015), optical microscopy (Hartmann et al, 2004;Vass et al, 2013;Bourges et al, 2020), methods of growing single-cell organisms in HP environments (Vezzi et al, 2005;Kato, 2006;Takai et al, 2008), tools to facilitate bioinformatic mining of extremophile genomes (Grö tzinger et al, 2014;Black et al, 2013) and molecular dynamics simulations for molecules in HP environments (Ingr et al, 2016;Silva et al, 2015;Garcia & Paschek, 2008;Sarupria et al, 2010;Paschek et al, 2005;Prigozhin et al, 2019).…”

Pressure tolerance of deep‐sea enzymes can be evolved through increasing volume changes in protein transitions: a study with lactate dehydrogenases from abyssal and hadal fishes

“…The mechanisms of high-pressure adaptation that allow the enzymes of piezophiles to cope with the effects of pressure on the protein conformational landscapes are particularly important for multimeric enzymes. Due to the large positive volume changes inherent to protein-protein interactions [16,36,43,44], pressure commonly induces dissociation of protein oligomers. This dissociation is one of the causes underlying the inhibitory effects of pressure on multimeric enzymes, such as lactate dehydrogenase (LDH), glyceraldehyde-3-phosphate dehydrogenase (GPDH), and malate dehydrogenase (MDH).…”