Acid—base indicator equilibria in the presence of aerosol-OT aggregates in heptane. Ion exchange in reversed micelles

Seoud, Omar A. El; Chinelatto, Ana M.; Shimizu, Maria R

doi:10.1016/0021-9797(82)90270-3

Cited by 60 publications

(43 citation statements)

References 19 publications

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“…Thymol blue is of intermediate hydrophilicity. It is a well-known acid-blue indicator used by El Seoud and Shimizu (1982) to define a pH for the interior of AOT reverse micelles. Fulton et al (1989) used it to probe the interiors of reverse micelles.…”

Section: Dye Solubilization Studies In the Cand/co/water Systemmentioning

confidence: 99%

Solubilization in nonionic reverse micelles in carbon dioxide

1994

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Phase behavior data and FTIR spectra along with solubilities and solvatochromic shifts of ionic indicator dyes are reported for binary, ternary and quaternary systems composed of pentaethylene glycol n-octyl ether ( C,E,), COB water, and n-pentanol as a function of temperature, pressure and composition. With the addition of npentanol as a cosurfactant, the water to surfactant ratio, W,,, reaches values as high as 12. As water is added further, a surfactant-rich phase precipitates due to micellemicelle inreractions. Ionic dyes are soluble at levels of 0.03 mM, far in excess of the negligible solubility in pure CO,.Highly pure CBES (Sigma) and C,2ES (Nikko) were used with- AIChE Journal, and solubilization reach a plateau, since the reverse micelle size and interfacial curvature remain constant.A different type of behavior is seen in the Triton X-100 system in a 70130 (v/v) mixture of hexane and benzene. The system contains 22.1 wt. 070 Triton X-100 at W,=O, which is

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Section: Dye Solubilization Studies In the Cand/co/water Systemmentioning

confidence: 99%

Solubilization in nonionic reverse micelles in carbon dioxide

1994

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“…Some published papers have shown a dependence of the pK a on the nature of the buffer and on the water-surfactant molar ratio (3,4). The pH shifts arise from a combination of electrostatic and microenviromental effects of the micelles (18)(19)(20)(21)(22)(23)(24).…”

Section: Introductionmentioning

confidence: 98%

Application of Multiple Linear Regression and Extended Principal-Component Analysis to Determination of the Acid Dissociation Constant of 7-Hydroxycoumarin in Water/AOT/Isooctane Reverse Micelles

Caselli

Daniele

Mangone

et al. 2000

Journal of Colloid and Interface Science

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“…The degree of quenching is very different for denaturated cutinase in AOT reverse micelles with W 0 20 (184% of initial fluorescence intensity) and W 0 5 (470% of initial fluorescence intensity). Functionally similar denaturated states (similar activities) can have very different tryptophan-quenching efficiencies, due probably to the highly quenched state of the single tryptophan residue in the native state or to different physicochemical properties of the water-pool at W 0 5 and 20, such as pH and viscosity (Hasegawa et al, 1994: Seoud et al, 1982Zinsli, 1979).…”

Section: Discussionmentioning

confidence: 99%

Deactivation and conformational changes of cutinase in reverse micelles

Melo

Carvalho²,

Aires-Barros³

et al. 1998

Biotechnol. Bioeng.

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Deactivation data and fluorescence intensity changes were used to probe functional and structural stability of cutinase in reverse micelles. A fast deactivation of cutinase in anionic (AOT) reverse micelles occurs due to a reversible denaturation process. The deactivation and denaturation of cutinase is slower in small cationic (CTAB/1‐hexanol) reverse micelles and does not occur when the size of the cationic reverse micellar water‐pool is larger than cutinase. In both systems, activity loss and denaturation are coupled processes showing the same trend with time. Denaturation is probably caused by the interaction between the enzyme and the surfactant interface of the reversed micelle. When the size of the empty reversed micelle water‐pool is smaller than cutinase (at W0 5, with W0 being the water:surfactant concentration ratio) a three‐state model describes denaturation and deactivation with an intermediate conformational state existing on the path from native to denaturated cutinase. This intermediate was clearly detected by an increase in activity and shows only minor conformational changes relative to the native state. At W0 20, the size of the empty water‐pool was larger than cutinase and the data was well described by a two‐state model for both anionic and cationic reverse micelles. For AOT reverse micelles at W0 20, the intermediate state became a transient state and the deactivation and denaturation were described by a two‐state model in which only native and denaturated cutinase were present. For CTAB/1‐hexanol reverse micelles at W0 20, the native cutinase was in equilibrium with an intermediate state, which did not suffer denaturation. 1‐Hexanol showed a stabilizing effect on cutinase in reverse micelles, contributing to the higher stabilities observed in the cationic CTAB/1‐hexanol reverse micelles. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:380–386, 1998.

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Acid—base indicator equilibria in the presence of aerosol-OT aggregates in heptane. Ion exchange in reversed micelles

Cited by 60 publications

References 19 publications

Solubilization in nonionic reverse micelles in carbon dioxide

Solubilization in nonionic reverse micelles in carbon dioxide

Application of Multiple Linear Regression and Extended Principal-Component Analysis to Determination of the Acid Dissociation Constant of 7-Hydroxycoumarin in Water/AOT/Isooctane Reverse Micelles

Deactivation and conformational changes of cutinase in reverse micelles

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