Predicting equilibrium constants for ion exchange of proteins — a colloid science approach

Bowen, W. Richard; Pan, Li Chun; Sharif, Adel O.

doi:10.1016/s0927-7757(98)00512-3

Cited by 14 publications

(10 citation statements)

References 27 publications

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“…The interaction between protein and adsorbent could be treated as a colloidal interaction, which is well characterized by zeta potential (26–28). The zeta potential depends on the surface charge of colloidal particle and environmental properties, such as pH and ionic strength.…”

Section: Resultsmentioning

confidence: 99%

“…The increase of ionic strength leads to a decrease of the electrostatic interactions or, in other words, the decrease of the equilibrium constant in the SMA model. With the other theoretical framework different from the SMA model, Bowen et al also found that in their model the ion exchange equilibrium constant of BSA binding to QA52 ion exchanger decreased with increasing ionic strength (26).…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Influence of pH and Ionic Strength on the Steric Mass-Action Model Parameters around the Isoelectric Point of Protein

Shi

Zhou

Sun

2008

Biotechnol Progress

127

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The ion-exchange equilibrium and the dependence of the parameters in the steric mass-action (SMA) model on salt concentration and buffer pH around the isoelectric point of protein were studied. Bovine serum albumin (BSA, isoelectric point = 5.4) was used as a model protein and DEAE Sepharose FF as an ion exchanger. Finite batch adsorption experiments and isocratic elution chromatography were performed for the determination of the model parameters (i.e., characteristic charge, equilibrium constant, and steric factor). The results showed that pH had significant effects on the parameters. With an increase of pH from 4.5 to 6.5, the characteristic charge increased from 0.9 to 3.0 and leveled off as a plateau at pH above 5.5. The charge groups in the contact region of protein surface were considered to play a crucial role on the characteristic charge. The decrease of pH and increase of salt concentration lowered the absolute value of the zeta potential of the protein surface and led to a decrease of the equilibrium constant. The steric factor remained unchanged at about 31 at pH 5.5 and 6.0 and increased to 44.5 at pH 5.0 and 96.8 at pH 4.5, mainly as a result of the lower adsorption capacity of BSA at pH <5.5. Furthermore, the increase of the molecular volume of BSA at pH 4.5 would be an additional reason for the increase of the steric factor. Taking into account the effect of the pH and salt concentration on these parameters, the SMA model described the ion exchange equilibrium of protein more accurately.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Influence of pH and Ionic Strength on the Steric Mass-Action Model Parameters around the Isoelectric Point of Protein

Shi

Zhou

Sun

2008

Biotechnol Progress

127

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“…In this case, one cannot simply use the results established by considering the membrane as a flat homogeneous plane (such as the one giving the DLVO potential for a sphere-infinite plane geometry, for instance) and a more realistic approach has to be developed. This significantly complicates any calculation of particle-membrane interactions [43][44][45][46]. Also, the description of the particle convective motion towards the membrane is also made much more complex when working at pore scale, as the hydrodynamic interactions between the particle and the membrane have to be accounted for.…”

Section: Towards a Pore Scale Approachmentioning

confidence: 99%

Colloidal surface interactions and membrane fouling: Investigations at pore scale

Bacchin

Marty

Duru

et al. 2011

Advances in Colloid and Interface Science

112

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“…Several models have been considered to describe adsorption of charged species at charged interfaces based on the Poisson-Boltzmann equation. The simplified case corresponding to adsorption of spheres with an evenly distributed net-charge has been treated, [9][10][11][12][13][14][15] and other approaches include structural features and orientation of the macromolecule. [16][17][18] An important difference is the fact that the later approach introduces some anisotropy in the charge distribution on the protein, as it has long been recognized that protein adsorption at charged interfaces cannot be satisfactorily explained by the overall net-charge, [19][20][21] due to the asymmetrical distribution of groups of different charge on the protein surface.…”

Section: ' Introductionmentioning

confidence: 99%

Protein Adsorption at Charged Surfaces: The Role of Electrostatic Interactions and Interfacial Charge Regulation

et al. 2011

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The understanding of protein adsorption at charged surfaces is important for a wide range of scientific disciplines including surface engineering, separation sciences and pharmaceutical sciences. Compared to chemical entities having a permanent charge, the adsorption of small ampholytes and proteins is more complicated as the pH near a charged surface can be significantly different from the value in bulk solution. In this work, we have developed a phenomenological adsorption model which takes into account the combined role of interfacial ion distribution, interfacial charge regulation of amino acids in the proximity of the surface, electroneutrality, and mass balance. The model is straightforward to apply to a given set of experimental conditions as most model parameters are obtained from bulk properties and therefore easy to estimate or are directly measurable. The model provides a detailed understanding of the importance of surface charge on adsorption and in particular of how changes in surface charge, concentration, and surface area may affect adsorption behavior. The model is successfully used to explain the experimental adsorption behavior of the two model proteins lysozyme and α-lactalbumin. It is demonstrated that it is possible to predict the pH and surface charge dependent adsorption behavior from experimental or theoretical estimates of a preferred orientation of a protein at a solid charged interface.

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Predicting equilibrium constants for ion exchange of proteins — a colloid science approach

Cited by 14 publications

References 27 publications

Influence of pH and Ionic Strength on the Steric Mass-Action Model Parameters around the Isoelectric Point of Protein

Influence of pH and Ionic Strength on the Steric Mass-Action Model Parameters around the Isoelectric Point of Protein

Colloidal surface interactions and membrane fouling: Investigations at pore scale

Protein Adsorption at Charged Surfaces: The Role of Electrostatic Interactions and Interfacial Charge Regulation

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