Kinetic Properties of Enzymes in Reversed Micelles

Ishikawa, Haruo; Noda, Katsura; Oka, Takashi

doi:10.1111/j.1749-6632.1990.tb18214.x

“…When the assumptions in case 2 apply, only the second and the fourth reactions in eqn. (13) are important. The model predictions now depend on the two enzyme efficiencies η b,b and η f,b , representing bioconversion of the substrate in the bound water with enzyme in the bound water and in the free water respectively.…”

Section: Model 2 : Interactions Between Enzyme and Micellesmentioning

confidence: 99%

“…Micellar aggregates have been suggested as catalysts for organic chemical reactions on the basis that the reactants can interact with the micelles, thereby improving the yield [2]. Studies have been reported over the past fifteen years into the use of surfactants in reverse micelle bioprocessing applications : surfactant micro-emulsions [3][4][5][6], the extraction of active enzymes [7] and the preparation of media for hosting enzymic reactions [4,[8][9][10][11][12][13][14][15][16][17][18]. In contrast, enzymic biocatalysis in aqueous solutions of buffer and surfactant has been largely disregarded.…”

Section: Introductionmentioning

confidence: 99%

Models for enzyme superactivity in aqueous solutions of surfactants

Viparelli

¹

,

Alfani²,

Cantarella

³

1999

Biochemical Journal

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Theoretical models are developed here for enzymic activity in the presence of direct micellar aggregates. An approach similar to that of Bru et al. [Bru, Sánchez-Ferrer and Garcia-Carmona (1989) Biochem. J. 259, 355-361] for reverse micelles has been adopted. The system is considered to consist of three pseudo-phases: free water, bound water and surfactant tails. The substrate concentration in each pseudo-phase is related to the total substrate concentration in the reaction medium. In the absence of interactions between the enzyme and the micelles, the model predicts either monotonically increasing or monotonically decreasing trends in the calculated reaction rate as a function of surfactant concentration. With enzyme-micelle interactions included in the formulation (by introducing an equilibrium relation between the enzyme confined in the free water and in the bound water pseudo-phases, and by allowing for different catalytic behaviours for the two forms), the calculated reaction rate can exhibit a bell-shaped dependence on surfactant concentration. The effect of the partition of enzyme and substrate is described, as is that of enzyme efficiency in the various pseudo-phases.

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“…Although oxygen readily dissolves in water, decreased reaction rates in RMs [29,30] have been attributed to the slower O 2 diffusion in a suspension of RMs compared to water [31]. The oxidation of ascorbic acid by vanadate was recently investigated [14], and since vanadium (abbreviated V) is a very sensitive spectroscopic probe, this reaction provided information on confinement on ascorbic acid reactions [24,25].…”

Section: Introductionmentioning

confidence: 99%

Impairment of ascorbic acid’s anti-oxidant properties in confined media: Inter and intramolecular reactions with air and vanadate at acidic pH

Crans

¹

,

Baruah

²

,

Gaidamauskas

³

et al. 2008

Journal of Inorganic Biochemistry

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“…l When the assumptions in case 2 apply, only the second and the fourth reactions in eqn. (13) are important. The model predictions now depend on the two enzyme efficiencies η b,b and η f,b , representing bioconversion of the substrate in the bound water with enzyme in the bound water and in the free water respectively.…”

Section: Model 2 : Interactions Between Enzyme and Micellesmentioning

confidence: 99%

“…Micellar aggregates have been suggested as catalysts for organic chemical reactions on the basis that the reactants can interact with the micelles, thereby improving the yield [2]. Studies have been reported over the past fifteen years into the use of surfactants in reverse micelle bioprocessing applications : surfactant micro-emulsions [3][4][5][6], the extraction of active enzymes [7] and the preparation of media for hosting enzymic reactions [4,[8][9][10][11][12][13][14][15][16][17][18]. In contrast, enzymic biocatalysis in aqueous solutions of buffer and surfactant has been largely disregarded.…”

Section: Introductionmentioning

confidence: 99%

Models for enzyme superactivity in aqueous solutions of surfactants

Viparelli¹,

Alfani²,

Cantarella³

1999

View full text Add to dashboard Cite

Theoretical models are developed here for enzymic activity in the presence of direct micellar aggregates. An approach similar to that of Bru et al. [Bru, Sánchez-Ferrer and Garcia-Carmona (1989) Biochem. J. 259, 355-361] for reverse micelles has been adopted. The system is considered to consist of three pseudo-phases: free water, bound water and surfactant tails. The substrate concentration in each pseudo-phase is related to the total substrate concentration in the reaction medium. In the absence of interactions between the enzyme and the micelles, the model predicts either monotonically increasing or monotonically decreasing trends in the calculated reaction rate as a function of surfactant concentration. With enzyme-micelle interactions included in the formulation (by introducing an equilibrium relation between the enzyme confined in the free water and in the bound water pseudo-phases, and by allowing for different catalytic behaviours for the two forms), the calculated reaction rate can exhibit a bell-shaped dependence on surfactant concentration. The effect of the partition of enzyme and substrate is described, as is that of enzyme efficiency in the various pseudo-phases.

show abstract

Kinetic Properties of Enzymes in Reversed Micelles

Cited by 6 publications

References 6 publications

Models for enzyme superactivity in aqueous solutions of surfactants

Models for enzyme superactivity in aqueous solutions of surfactants

Impairment of ascorbic acid’s anti-oxidant properties in confined media: Inter and intramolecular reactions with air and vanadate at acidic pH

Models for enzyme superactivity in aqueous solutions of surfactants

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