Proteins as Invited Guests of Reverse Micelles: Conformational Effects, Significance, Applications

Nicot, C.; Waks, Marcel

doi:10.1080/02648725.1996.10647932

Cited by 31 publications

(25 citation statements)

References 132 publications

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“…We have shown previously that in AOT reverse micelles MBP refolds from an unordered structure to a stable, ordered conformation, much less prone to proteolysis than the flexible aqueous form (Nicot et al, 1993). The micellar cavity thus provides MBP with a chaperonin-like microenvironment, where micelle-assisted folding can proceed in the absence of aggregation (Nicot and Waks, 1995).…”

Section: Mbpmentioning

confidence: 96%

“…Experiments under conditions in which protein would be only partially solubilized and remain suspended in the oil (i.e., turbid samples detected by optical density at 350 nm) were ruled out, as they would not have been optically transparent. The conformational properties of the above proteins in reverse micelles have been reviewed, and they do not denature during the solubilization process (Nicot and Waks, 1995). By systematically applying this procedure, we have found limits of solubilization for each protein studied as a function of W 0 in relation to their respective size and surface charges.…”

Section: Sample Preparationmentioning

confidence: 98%

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Hydration and Protein Folding in Water and in Reverse Micelles: Compressibility and Volume Changes

Valdez

Huerou

Gindre

et al. 2001

Biophysical Journal

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The partial specific volume and adiabatic compressibility of proteins reflect the hydration properties of the solvent-exposed protein surface, as well as changes in conformational states. Reverse micelles, or water-in-oil microemulsions, are protein-sized, optically-clear microassemblies in which hydration can be experimentally controlled. We explore, by densimetry and ultrasound velocimetry, three basic proteins: cytochrome c, lysozyme, and myelin basic protein in reverse micelles made of sodium bis (2-ethylhexyl) sulfosuccinate, water, and isooctane and in aqueous solvents. For comparison, we use beta-lactoglobulin (pI = 5.1) as a reference protein. We examine the partial specific volume and adiabatic compressibility of the proteins at increasing levels of micellar hydration. For the lowest water content compatible with complete solubilization, all proteins display their highest compressibility values, independent of their amino acid sequence and charge. These values lie within the range of empirical intrinsic protein compressibility estimates. In addition, we obtain volumetric data for the transition of myelin basic protein from its initially unfolded state in water free of denaturants, to a folded, compact conformation within the water-controlled microenvironment of reverse micelles. These results disclose yet another aspect of the protein structural properties observed in membrane-mimetic molecular assemblies.

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Section: Mbpmentioning

confidence: 96%

Section: Sample Preparationmentioning

confidence: 98%

Hydration and Protein Folding in Water and in Reverse Micelles: Compressibility and Volume Changes

Valdez

Huerou

Gindre

et al. 2001

Biophysical Journal

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“…The facts that proteins entrapped within reverse micelles retain activity make them good model systems for understanding the properties of proteins in a cell-like environment [17][18][19][20][21][22][23][24][25][26][27][28]. The reverse micellar system based upon the use of anionic surfactant AOT (sodium bis-(2-ethylhexyl)-sulfosuccinate) is well known [17][18][19][20][21][22][23][24][25][26][27][28]. AOT-isooctane-water micelles are characterized by a relatively narrow distribution of their dimensions.…”

Section: Introductionmentioning

confidence: 99%

Positive cooperativity in substrate binding of human prostatic acid phosphatase entrapped in AOT–isooctane–water reverse micelles

Luchter-Wasylewska

Iciek

2004

Journal of Colloid and Interface Science

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“…22 Still the structural reason of this denaturation may be different since cytochrome C interacting with AOT loses its tertiary structure whereas human serum albumin loses its periodic structure. 23 In relation to polyphenol oxidase, the effect of surfactants has been widely studied since the latent enzyme in crude extracts is activated by surfactants to an extent that depends on the nature of the surfactant, the cationic ones being more ef®cient in activating it. 24 But if polyphenol oxidase becomes puri®ed, the effect of surfactants on it varies from the lack of effect of AOT and the inactivation of SDS 25 to the activation of up to 17 mmol dm À3 SDS.…”

Section: Thermal Stability Of Polyphenol Oxidasementioning

confidence: 99%

Polyphenol oxidase in reverse micelles of AOT/cyclohexane: A thermostability study

Rojo

Gómez

Estrada

2001

J. Chem. Technol. Biotechnol.

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Polyphenol oxidase catalysing the oxidation of 4-methylcatechol in reverse micelles of AOT/cyclohexane had an optimum temperature 15°C higher than in aqueous medium. However, the enzyme lost stability when it was preincubated in reverse micelles in the absence of substrate regardless of the temperature although the effect was more pronounced at higher temperatures. The thermostability of polyphenol oxidase is higher when it is injected in reverse micelles containing buffer than when injected in initially empty micelles. Moreover, the thermostability of polyphenol oxidase in reverse micelles is strongly dependent on the size of the micelles, the bigger the micelle the greater the stability. The thermoinactivation of the enzyme follows a monomolecular process characteristic of a conformational change so the protein is protected by ligands towards inactivation. p-Nitrophenol as competitive inhibitor and acetyl tyrosine ethyl ester as alternate substrate increase the half-life of the polyphenol oxidase by about 2.5 and 4 times respectively. This ®nding may allow the use of the enzyme at higher temperatures with a gain in its stability.

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Proteins as Invited Guests of Reverse Micelles: Conformational Effects, Significance, Applications

Cited by 31 publications

References 132 publications

Hydration and Protein Folding in Water and in Reverse Micelles: Compressibility and Volume Changes

Hydration and Protein Folding in Water and in Reverse Micelles: Compressibility and Volume Changes

Positive cooperativity in substrate binding of human prostatic acid phosphatase entrapped in AOT–isooctane–water reverse micelles

Polyphenol oxidase in reverse micelles of AOT/cyclohexane: A thermostability study

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