Effects of pH on protein–protein interactions and implications for protein phase behavior

Dumetz, André C.; Chockla, Aaron Michael; Kaler, Eric W.; Lenhoff, Abraham M.

doi:10.1016/j.bbapap.2007.12.016

Cited by 117 publications

(107 citation statements)

References 81 publications

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“…73 If one is concerned about only the sign of B 22 , A 2 , or G 22 , then Eqs. (11), (24) or (26), (30), and (27) 53 ) suggests that contributions from Donnan equilibria involving the proteins and the counterions are not significant for the present examples, within experimental uncertainty. As shown above, A 2 from traditional analysis is not equal to B 22 unless the magnitude of c 2 B 22 (or c 2 G 22 ) is small compared to 1.…”

Section: B Classical Analysis Vs Kb Analysismentioning

confidence: 61%

“…18,42,59 This provides a means to test not only whether the de novo expressions can provide reasonable fits to the experimental data, but also to assess differences in the resulting values of G 22 and M 2,app compared to A 2 and M 2 in the classical LS analysis. (11), (26), (30), and (27) , no difference can be observed between these expressions. However, for large deviations, differences between the de novo equations (Eqs.…”

Section: B Classical Analysis Vs Kb Analysismentioning

confidence: 88%

“…9,10,28 More recent work highlights the importance of considering an equivalent hard-sphere (HS) or purely steric proteinprotein interaction (i.e., B H S 22 ) as a more appropriate reference point. 24,[29][30][31] That is, systems with B 22 Recent experimental comparisons between LS and alternative means to estimate B 22 have led some authors to conclude that LS fundamentally does not yield B 22 as an independent quantity -i.e., that the apparent virial coefficient (A 2 ) from traditional LS analysis is instead a convolution of B 22 with protein-cosolute and/or (co)solvent virial coefficients. 32,33 This is potentially problematic, as LS is arguably the historic method of choice for determining B 22 , and is the basis for much if not the majority of experimental B 22 values reported in the literature.…”

Section: Introductionmentioning

confidence: 99%

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Reexamining protein–protein and protein–solvent interactions from Kirkwood-Buff analysis of light scattering in multi-component solutions

Blanco¹,

Şahin²,

Li³

et al. 2011

The Journal of Chemical Physics

203

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The classic analysis of Rayleigh light scattering (LS) is re-examined for multi-component protein solutions, within the context of Kirkwood-Buff (KB) theory as well as a more generalized canonical treatment. Significant differences arise when traditional treatments that approximate constant pressure and neglect concentration fluctuations in one or more (co)solvent/co-solute species are compared with more rigorous treatments at constant volume and with all species free to fluctuate. For dilute solutions, it is shown that LS can be used to rigorously and unambiguously obtain values for the osmotic second virial coefficient (B 22 ), in contrast with recent arguments regarding protein interactions deduced from LS experiments. For more concentrated solutions, it is shown that conventional analysis over(under)-estimates the magnitude of B 22 for significantly repulsive(attractive) conditions, and that protein-protein KB integrals (G 22 ) are the more relevant quantity obtainable from LS. Published data for α-chymotrypsinogen A and a series of monoclonal antibodies at different pH and salt concentrations are re-analyzed using traditional and new treatments. The results illustrate that while traditional analysis may be sufficient if one is interested in only the sign of B 22 or G 22 , the quantitative values can be significantly in error. A simple approach is illustrated for determining whether protein concentration (c 2 ) is sufficiently dilute for B 22 to apply, and for correcting B 22 values from traditional LS regression at higher c 2 values. The apparent molecular weight M 2,app obtained from LS is shown to generally not be equal to the true molecular weight, with the differences arising from a combination of protein-solute and protein-cosolute interactions that may, in principle, also be determined from LS.

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Section: B Classical Analysis Vs Kb Analysismentioning

confidence: 61%

Section: B Classical Analysis Vs Kb Analysismentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Reexamining protein–protein and protein–solvent interactions from Kirkwood-Buff analysis of light scattering in multi-component solutions

Blanco¹,

Şahin²,

Li³

et al. 2011

The Journal of Chemical Physics

203

View full text Add to dashboard Cite

show abstract

“…At high salt concentrations, protein-protein interactions become favourable over electrostatic repulsion and this is the driving force for precipitation [48,49] and aggregation [50]. It has also been reported that at low pH, protein-protein interactions become more favourable [51]. It is likely that this combination of effects served to pre-concentrate the protein at or near the interface at the highest LiCl concentration.…”

Section: Influence Of the Aqueous Phase Ionic Strengthmentioning

confidence: 99%

Electrochemical behaviour of myoglobin at an array of microscopic liquid–liquid interfaces

O'Sullivan

Arrigan

2012

Electrochimica Acta

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Electrochemistry at liquid-liquid interfaces, or at interfaces between two immiscible electrolyte solutions (ITIES), provides a basis for the non-redox detection of biological molecules, based on iontransfer or adsorption processes. The electroactivity of myoglobin at an array of micron-sized liquidorganogel interfaces was investigated. The µITIES array was patterned with a silicon membrane consisting of an array of eight pores with radii of ~12.8 µm and a pore to pore separation of ~400 µm.Using cyclic voltammetry at the ITIES, the protein was shown to adsorb at the interface and facilitate the transfer of the organic phase electrolyte anions to the aqueous side of the interface. The electrochemical current response was linear with concentration in the range of 1 -6 µM, with corresponding surface coverage of 10 -50 pmol cm -2 . The reverse peak currents was found to be proportional to the voltammetric scan rate, indicating a desorption process. The detection of the protein was only possibly when the pH of the aqueous phase solution was below the pI of the protein. The steady-state simple ion transfer behaviour of tetraethylammonium cation was decreased on the forward sweep, providing a qualitative indication of the presence of adsorbed protein at the interface.Increasing the ionic strength of the aqueous phase resulted in enhanced peak currents, possibly due to aggregation of protein precipitates in the aqueous solution. UV/Vis absorbance spectroscopy was used 1 ISE Member.2 | P a g e to investigate the effects of various aqueous electrolyte solutions on the structure of the protein, and it was shown that at low pH the protein is at least partially denatured. These results provide the basis for label-free detection of myoglobin at the ITIES.

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“…Under these solution conditions and in the investigated temperature interval all B 22 data are negative and lie between -7 and -1 · 10 -4 mol · ml · g -2 . These are solution conditions favoring crystallization [83][84][85][86][87].…”

Section: Effect Of Temperaturementioning

confidence: 99%

Lysozyme‐lysozyme self‐interactions as assessed by the osmotic second virial coefficient: Impact for physical protein stabilization

Brun¹,

Frieß²,

Schultz-Fademrecht

et al. 2009

Biotechnology Journal

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The purpose of the presented study is to understand the physicochemical properties of proteins in aqueous solutions in order to identify solution conditions with reduced attractive protein‐protein interactions, to avoid the formation of protein aggregates and to increase protein solubility. This is assessed by measuring the osmotic second virial coefficient (B22), a parameter of solution non‐ideality, which is obtained using self‐interaction chromatography. The model protein is lysozyme. The influence of various solution conditions on B22 was investigated: protonation degree, ionic strength, pharmaceutical relevant excipients and combinations thereof. Under acidic solution conditions B22 is positive, favoring protein repulsion. A similar trend is observed for the variation of the NaCl concentration, showing that with increasing the ionic strength protein attraction is more likely. B22 decreases and becomes negative. Thus, solution conditions are obtained favoring attractive protein‐protein interactions. The B22 parameter also reflects, in general, the influence of the salts of the Hofmeister series with regard to their salting‐in/salting‐out effect. It is also shown that B22 correlates with protein solubility as well as physical protein stability.

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Effects of pH on protein–protein interactions and implications for protein phase behavior

Cited by 117 publications

References 81 publications

Reexamining protein–protein and protein–solvent interactions from Kirkwood-Buff analysis of light scattering in multi-component solutions

Reexamining protein–protein and protein–solvent interactions from Kirkwood-Buff analysis of light scattering in multi-component solutions

Electrochemical behaviour of myoglobin at an array of microscopic liquid–liquid interfaces

Lysozyme‐lysozyme self‐interactions as assessed by the osmotic second virial coefficient: Impact for physical protein stabilization

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