Micelle clusters of octylhydroxyoligo(oxyethylenes)

Zulauf, M.; Rosenbusch, J P

doi:10.1021/j100228a032

Cited by 180 publications

(125 citation statements)

References 2 publications

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“…Micelles of small detergents can exhibit dramatic fluctuations in micellar shape; they can deform, split, and fuse over time (10,11,17,18). For some detergents, appreciable changes in micelle aggregation number, size, and shape may occur as the total detergent concentration rises (22,23). Changes in micelle shape, from spherical to ellipsoidal or even rodlike, occur with many pure detergents (22,23) but may be even more common when a detergent is mixed with another detergent, lipid, or protein (24).…”

Section: Detergents and Lipids As Surfactantsmentioning

confidence: 99%

Detergents as Tools in Membrane Biochemistry

Garavito

Ferguson‐Miller

2001

Journal of Biological Chemistry

498

441

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Detergents are invaluable tools for studying membrane proteins. However, these deceptively simple, amphipathic molecules exhibit complex behavior when they self-associate and interact with other molecules. The phase behavior and assembled structures of detergents are markedly influenced not only by their unique chemical and physical properties but also by concentration, ionic conditions, and the presence of other lipids and proteins. In this minireview, we discuss the various aggregate forms detergents assume and some misconceptions about their structure. The distinction between detergents and the membrane lipids that they may (or may not) replace is emphasized in the most recent high resolution structures of membrane proteins. Detergents are clearly friends and foes, but with the knowledge of how they work, we can use the increasing variety of detergents to our advantage.Over the past decade, our understanding of the structure and function of membrane proteins has advanced significantly as well as how their detailed characterization can be approached experimentally. Detergents have played significant roles in this effort. They serve as tools to isolate, solubilize, and manipulate membrane proteins for subsequent biochemical and physical characterization. Many of the successful methods for reconstituting (1) and crystallizing (2-4) membrane proteins rely on the unique behavior of detergents. Although many new detergents are now available for use with membrane proteins, their behavior in solution and in the presence of protein may limit their use with specific experimental techniques. Hence, the choice of detergent and experimental conditions will have an enormous impact on whether a technique can be successfully applied to a specific membrane protein. A clear understanding of basic detergent behavior and of the structure of micelles and protein-detergent complexes is thus crucial for membrane biochemists.

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Section: Detergents and Lipids As Surfactantsmentioning

confidence: 99%

Detergents as Tools in Membrane Biochemistry

Garavito

Ferguson‐Miller

2001

Journal of Biological Chemistry

498

441

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“…This leads to stronger van der Waals interactions between the micelles and the formation of micelle clusters. It is believed that the size of the micelle does not change upon heating (7), but the size of the clusters increases asymtotically and follows a power-law given by (T d Ϫ T)/T d (4,6). The attractive forces between micelles can also be increased at a fixed temperature, T, by the addition of certain inorganic salts, especially phosphate or fluoride salts, or by mixing with a detergent with a lower T d (2).…”

mentioning

confidence: 99%

A Mechanism to Alter Reversibly the Oligomeric State of a Membrane-bound Protein Demonstrated with Escherichia coliEIImtl in Solution

Broos

Hoeve-Duurkens

Robillard

1998

Journal of Biological Chemistry

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This paper reports that the aggregation state of a membrane protein can be changed reversibly without the use of chaotropic agents or denaturants by altering the attractive interactions between micelles of polyethylene glycol-based detergents. This has been documented using mannitol permease of Escherichia coli (EII mtl ), a protein whose activity is dependent on the dimerization of its membrane-embedded domains. We show that the driving force for the hydrophobic interactions responsible for the dimerization can be decreased by bringing the protein into a less polar environment. This can be done simply and reversibly by increasing the micelle cluster size of the solubilizing detergent since the micropolarity in the micelle decreases upon clustering and is directly related to the cluster size.The micelle cluster size was varied at a fixed temperature by adding sodium phosphate or a second detergent with a distinct clustering behavior, and the changes were quantified by quasi-elastic light scattering and by determining the cloud point or demixing temperature (T d ) of the detergent. Maximal EII mtl activity was found when no micelle clustering occurred, but the activity gradually decreased down to 5% of the maximal activity with increasing cluster size. The inactivation was found to be completely reversible. The kinetics of heterodimer formation were also significantly affected by changes in the micelle cluster size as expected. Increasing the cluster size resulted in faster formation of functional heterodimers by increasing the rate of homodimer dissociation. This phenomenon should be generally applicable to controlling the oligomeric state of membrane-bound proteins or even water-soluble proteins if their subunit association is dominated by hydrophobic forces.It is well documented that the micropolarity of PEG-based 1 detergent micelles decreases when they form clusters and that this decrease is directly related to the micelle cluster size (1-3). In principle, this decrease in micropolarity should be able to be used to transfer a membrane protein, solubilized by such a detergent, to a less polar environment. Only PEG-based detergents show this clustering behavior. It can be induced by heating where, at a certain temperature, the cloud point or demixing temperature (T d ), the cluster size reaches a value which initiates separation of the micellar phase into two new micellar phases, one consisting of the micellar clusters and one containing a low concentration of micelles (2). Phase separation or demixing of PEG-based detergents into two new micellar phases at T d upon heating has been studied in detail with various techniques such as light, neutron and x-ray scattering, viscosity measurements, and NMR spin lattice relaxation (2, 4 -8). Such studies suggest that the intermicellar forces become stronger upon heating due to a decrease of the hydration of the PEG chains. This leads to stronger van der Waals interactions between the micelles and the formation of micelle clusters. It is believed that the size of the m...

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“…Alternatively, a defined volume of PBS was added to the starting solution by rapid mixing to obtain a specific end concentration ('rapid' dilution), Changes of particle sizes were measured by quasi-elastic light scattering, monitoring the amount of scattered light and the hydrodynamic radius &l, All lecithin s qmples without protein could be filtered easily, even when aggregate sizes were large at the phase transition, By contrast, when lecithin and protein were present, very lerge aggregates formed that clogged the filter, in these instances, the filtering was omitted to obtain unbiased values for the radii, During a dilution series the sizes of the a88regat:s changed because an increasing number of detergent molecules were removed from the aggregates to maintain the monornedc detergent concentration in the solvent at the critical rnicelle concentration (CMC [18]), The amount of detergent available for solubilization is the total amount of detergent minus its CMC, For example, the CMC of 8-POE in PBS at room temperature is 2.8 mg/rnl (8 rnM). Therefore, a solution with 12,5 m$hnl (35,7 rnM) 8-POE contains 9,7 rng/ml (27.7 aM) solubilization-competent 8-POE (Mr = 350), Since a micelle (Rh = 23 :l: 2 ~, Mr = 26250) contains about 75 deteqlent monomers [19], the rnicelle moladty is 370 IAM, Hence, we find on average 3,5 lecithin molecules per miceile in a solution containing I rng/ml 0,3 rnM) lecithin (Mr = 775) and 12,5 mg/ml 8-POE, Upon dilution of this solution, the lipid and dete~gent concentration decrease, For example, at a dilution by a lactor of 4, the lipid concentration is 0,25 rng/ml (325 pM), that of 8-POE is 3,125 rng/rnl (8,9 rnM) and the amount of solubilization<ompetent 8-POE is 0,325 rng/ml (900 pM), correspond, m8 to a rnicelle molarity of 12 pM, Therefore, there are 27 lipid molecules in a micelle resulting in an increased Rh of the lipid-deter, gent complexes,…”

Section: $ Dgution Seriesmentioning

confidence: 99%

The micelle to vesicle transition of lipids and detergents in the presence of a membrane protein: towards a rationale for 2D crystallization

1996

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The assembly of two-dimensional membrane protein crystals in the presence of lipids was analyzed with quasieinstic light scattering and electron microscopy. Mixtures of detergentsolubilized Upids and/or proteins were submitted to slow or rapid dilution while measuring the hydrodynamic radii of the aggregates. Lipids alone exhibited g-shaped dilution curves with intermediate rod-shaped particles that converted into small vesicles. Depending on the protein-protein and protein-lipid interactions, detergent-solubilized protein-lipid mixtures showed a sharp transition from mieelles to large, densely packed proteoliposomes. Electron microscopy revealed that formation of crystals occurred shortly after this phase transition.

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Micelle clusters of octylhydroxyoligo(oxyethylenes)

Cited by 180 publications

References 2 publications

Detergents as Tools in Membrane Biochemistry

Detergents as Tools in Membrane Biochemistry

A Mechanism to Alter Reversibly the Oligomeric State of a Membrane-bound Protein Demonstrated with Escherichia coliEIImtl in Solution

The micelle to vesicle transition of lipids and detergents in the presence of a membrane protein: towards a rationale for 2D crystallization

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