Statistical‐mechanical model of protein precipitation by nonionic polymer

Mahadevan, Hari; Hall, Carol K.

doi:10.1002/aic.690361007

Cited by 84 publications

(63 citation statements)

References 36 publications

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“…In this section we extend the theory of polymer-induced precipitation of single proteins by Mahadevan and Hall (1990) to binary mixtures of proteins.…”

Section: Development Of Theory: Size-related Effectsmentioning

confidence: 99%

“…The solid phase, however, is assumed to be pure. In other words, each protein is assumed to precipitate into its own solidphase; we do not allow for a solid-phase mixture (what we shall call coprecipitation), thus permitting the calculation of the solidphase free energies to be identical to that described by Mahadevan and Hall (1990). Thus, the free energies are calculated for one mixed fluid phase and two pure solid phases (protein 1 and protein 2), and a thermodynamic stability analysis is performed to decide which of the two species is actually at its solubility limit at the given conditions.…”

Section: Aiche Journalmentioning

confidence: 99%

“…We discuss the calculation of these quantities in the following section. The terms gA2(dI2) and hI2 are defined as: where and To predict phase transitions for the system it is necessary to calculate the chemical potentials pi of each species and the pressure, p , of the system (Gast et al, 1983;Mahadevan and Hall, 1990). These quantities can be calculated from the Helmholtz free energy as follows:…”

Section: Perturbation Theorymentioning

confidence: 99%

“…6 and 7. As mentioned earlier, the solidphase Helmholtz free energies were calculated for both solid phases in a manner identical to that described by Mahadevan and Hall (1990).…”

Section: Calculation Of Solubilitymentioning

confidence: 99%

“…In an earlier article (Mahadevan and Hall, 1990), we proposed a fundamental theory based on the work of Cast et al (1983) to explain the precipitation of pure proteins (singleprotein systems) by nonionic polymer. We were able to correctly predict the trends observed in the solubility resulting from changes in all the process variables: the pH, ionic strength and protein and polymer molecular weights.…”

Section: Introductionmentioning

confidence: 99%

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Theory of precipitation of protein mixtures by nonionic polymer

Mahadevan

Hall

1992

AIChE Journal

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A theory is developed to predict the solubility of protein mixtures in solutions containing nonionic polymer. Effective protein-protein interactions due to polymer are taken to be volume-exclusion potentials derived using statistical mechanics. Statistical-mechanical perturbation theory is used to calculate chemical potentials. The effects of protein size, mole fraction and polymer concentration on solubility are explored. The theory is extended to include electrostatic interactions. The excess chemical potential of the proteins due to the charges on all species is calculated using the mean spherical approximation for a mixture of charged hard spheres. The theory predicts: the larger protein is preferentially precipitated over the smaller one; the more concentratedprotein is more likely to precipitate; and increasing the charge of a particular protein reduces its ability to precipitate.

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“…In this section we extend the theory of polymer-induced precipitation of single proteins by Mahadevan and Hall (1990) to binary mixtures of proteins.…”

Section: Development Of Theory: Size-related Effectsmentioning

confidence: 99%

Section: Aiche Journalmentioning

confidence: 99%

Section: Perturbation Theorymentioning

confidence: 99%

“…6 and 7. As mentioned earlier, the solidphase Helmholtz free energies were calculated for both solid phases in a manner identical to that described by Mahadevan and Hall (1990).…”

Section: Calculation Of Solubilitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Theory of precipitation of protein mixtures by nonionic polymer

Mahadevan

Hall

1992

AIChE Journal

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Solute excluded-volume effects on the stability of globular proteins: A statistical thermodynamic theory

Zhou

Hall

1998

Biopolymers

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A statistical thermodynamic theory is developed to investigate the effects of solute excluded volume on the stability of globular proteins. Proteins are modeled as two states in chemical equilibrium: the denatured state is modeled as a flexible chain of tangent hard spheres (pearl‐necklace chain) while the native state is modeled as a single hard sphere. Study of model proteins bovine pancreatic trypsin inhibitor and lysozyme in a McMillan‐Mayer model solution of hard spheres indicates that the excluded volume of solutes has three distinct types of effects on protein stability: (1) small‐size solutes strongly denature proteins, (2) medium‐size solutes stabilize proteins at low solute concentrations and destabilize them at high concentrations, and (3) large‐size solutes stabilize native‐state proteins across the whole liquid region. The study also finds that increasing the chain length of hard‐chain polymer solutes has an effect on protein stability that is similar to increasing the diameter of spherical solutes. This work qualitatively explains why stabilizers tend to be large size molecules such as sugars, polymers, polynols, nonionic, and anionic surfactants while denaturants tend to be small size molecules such as alcohols, glycols, amides, formamides, ureas, and guanidium salts. Quantitative comparison between theoretical predictions and experimental results for folding free energy changes shows that the excluded‐volume effect is at least as important as the binding and/or electrostatic effects on solute‐assisted protein‐denaturation processes. Our theory may also be able to explain the effect of excluded volume on the Φ condensation of DNA. © 1996 John Wiley & Sons, Inc.

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Liquid‐liquid phase separations in aqueous solutions of globular proteins

Vlachy¹,

Blanch²,

Prausnitz³

1993

AIChE Journal

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A simple statistical‐mechanical theory, known as the random‐phase approximation, is applied to study liquid‐liquid phase separations in solutions of globular proteins. Phase separation may be induced by addition of nonionic polymer or/and ordinary electrolytes. In this analysis, the osmotic‐attraction mechanism, whereby the depletion of “solvent” particles between two proteins causes an attractive force, is primarily responsible for phase separation. For one‐component models of protein solutions, the theory yields simple algebraic expressions for the equation of state and for the chemical potential of the protein. This analytical theory describes the observed solubility behavior of proteins, including the effect of protein and polymer size, protein charge and concentration, and concentration of simple electrolytes.

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Statistical‐mechanical model of protein precipitation by nonionic polymer

Cited by 84 publications

References 36 publications

Theory of precipitation of protein mixtures by nonionic polymer

Theory of precipitation of protein mixtures by nonionic polymer

Solute excluded-volume effects on the stability of globular proteins: A statistical thermodynamic theory

Liquid‐liquid phase separations in aqueous solutions of globular proteins

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