Assessing the role of detergent–detergent interactions in membrane protein crystallization

Loll, Patrick J.; Allaman, Margaret M.; Wiencek, John M.

doi:10.1016/s0022-0248(01)01076-4

Cited by 36 publications

(50 citation statements)

References 7 publications

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“…Later, the existence of a crystallization slot for membrane proteins was demonstrated, and it was concluded that the detergent portion of the PDC is important in determining the B 22 values. 29,31 This finding implies that the detergent belt surrounding the hydrophobic part of the protein surface in the PDC remains fully intact in the course of crystallization and that detergent-detergent interactions (i.e., between detergent belts) are weakly attractive. Then, a simple picture emerges, according to which the PDC is a fixed entity behaving like a soluble protein and its aggregation behavior should be similar to and can be inferred from that of free (i.e., protein-free) micelles.…”

Section: Introductionmentioning

confidence: 89%

The influence of poly(ethylene glycol) on the micelle formation of alkyl maltosides used in membrane protein crystallization

Müh

DiFiore

Zouni

2015

Phys. Chem. Chem. Phys.

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With the aim of better understanding the phase behavior of alkyl maltosides (n-alkyl-b-D-maltosides, C n G 2 ) under the conditions of membrane protein crystallization, we studied the influence of poly(ethylene glycol) (PEG) 2000, a commonly used precipitating agent, on the critical micelle concentration (CMC) of the alkyl maltosides by systematic variation of the number n of carbon atoms in the alkyl chain (n = 10, 11, and 12) and the concentration of PEG2000 (w) in a buffer suitable for the crystallization of cyanobacterial photosystem II. CMC measurements were based on established fluorescence techniques using pyrene and 8-anilinonaphthalene-1-sulfonate (ANS). We found an increase of the CMC with increasing PEG concentration according to ln(CMC/CMC 0 ) = k P w, where CMC 0 is the CMC in the absence of PEG and k P is a constant that we termed the ''polymer constant''. In parallel, we measured the influence of PEG2000 on the surface tension of detergent-free buffer solutions. At PEG concentrations w 4 1% w/v, the surface pressure p s (w) = g(0) À g(w) was found to depend linearly on the PEG concentration according to p s (w) = kw + p s (0), where g (0) is the surface tension in the absence of PEG. Based on a molecular thermodynamic modeling, CMC shifts and surface pressure due to PEG are related, and it is shown that k P = kc(n) + Z, where c(n) is a detergent-specific constant depending inter alia on the alkyl chain length n and Z is a correction for molarity. Thus, knowledge of the surface pressure in the absence of a detergent allows for the prediction of the CMC shift. The PEG effect on the CMC is discussed concerning its molecular origin and its implications for membrane protein solubilization and crystallization.

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Section: Introductionmentioning

confidence: 89%

The influence of poly(ethylene glycol) on the micelle formation of alkyl maltosides used in membrane protein crystallization

Müh

DiFiore

Zouni

2015

Phys. Chem. Chem. Phys.

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“…(27) (26) and (27) show that A 2 from LS is more complex than simply B 22 , this is purely a consequence of not working at sufficiently low c 2 , and is not due to convolution with other osmotic virial coefficients or KB integrals. 33 The same cannot be stated for M 2,app , as this clearly depends on all G 2 j , independent of whether one uses Eq.…”

Section: B Revisiting the Canonical Treatment Of Rayleigh Scatteringmentioning

confidence: 99%

“…[25][26][27] In some cases, only the sign of B 22 is considered important, as a negative (positive) B 22 corresponds to net attractive (repulsive) protein-protein interactions relative to an ideal solution. 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.…”

Section: Introductionmentioning

confidence: 99%

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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“…Perhaps more signi®cantly, under OmpF crystallization conditions the B 22 behavior of protein-free detergent micelles is very similar to the B 22 behavior of complete PDCs. This implies that an understanding of micelle±micelle interactions occurring in pure detergent solutions may prove directly relevant to the crystallization of detergent-solubilized membrane proteins (Loll et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Effects of PEG on detergent micelles: implications for the crystallization of integral membrane proteins

Hitscherich

Aseyev

Wiencek

et al. 2001

Acta Crystallogr D Biol Cryst

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The solubilization of integral membrane proteins with detergents produces protein±detergent complexes (PDCs). Interactions between the detergent moieties of PDCs contribute signi®cantly to their behavior. The effects of the precipitating agent polyethylene glycol (PEG) upon these detergent±detergent interactions have been examined, focusing on the detergent system used to crystallize the bacterial outer membrane protein OmpF porin. Static and dynamic light scattering were used to assess the effects of temperature and concentration upon the hydrodynamic size distribution and the aggregation state of detergent micelles and a phase diagram for micellar solutions was mapped. Estimates of the second osmotic virial coef®cient obtained from static light-scattering measurements on micelles were shown to accurately re¯ect the thermodynamic quality of the solvent. Solvent quality decreases as the consolute boundary is approached, suggesting micelle±micelle attractive forces help to organize PDCs into crystalline aggregates near the cloud point. An apparent increase in micelle mass is observed as the solution approaches the cloud point. These results raise the possibility that the detergent-mediated aggregation of PDCs and/or slight changes in micelle geometry may prove to be important in the nucleation of membrane protein crystals.

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Assessing the role of detergent–detergent interactions in membrane protein crystallization

Cited by 36 publications

References 7 publications

The influence of poly(ethylene glycol) on the micelle formation of alkyl maltosides used in membrane protein crystallization

The influence of poly(ethylene glycol) on the micelle formation of alkyl maltosides used in membrane protein crystallization

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

Effects of PEG on detergent micelles: implications for the crystallization of integral membrane proteins

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