Micellar catalysis of polyphenol oxidase in AOT/cyclohexane

Rojo, Marta; Gómez, Marı́a; Isorna, P.; Estrada, P.

doi:10.1016/s1381-1177(00)00066-7

Cited by 14 publications

(6 citation statements)

References 14 publications

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“…As can be seen the catalytic activity of the enzyme in reverse micelles increases with increasing water/ surfactant molar ratio and reaches a maximum at w 0 higher than 20. However, in contrast to previously reported data using isooctane and cyclohexane (Bru et al ., 1989;Rodakiewicz-Nowak et al ., 2002;Rojo et al ., 2001) the profile of the (V max /[E]) (/w 0 dependence displays two extremes, at hydration degrees w 0 0/12 and w 0 0/25. At the hydration degree FIGURE 1 Dependence of (m) the enzymatic activity (V max /[E], min (1 ) of tyrosinase on the water/surfactant molar ratio, w 0 , in the system of reverse micelles of 0.1 M AOT in octane.…”

Section: Resultsmentioning

confidence: 99%

“…In dry organic media enzymatic activity of tyrosinase is drastically depressed due to enzyme inactivation by organic solvent: for retention of the catalytic activity a minimal water content is obligatory (Campanella et al ., 1994;Yang and Robb, 1993). Studies of tyrosinase in micellar systems resulted in determination of the optimum tyrosinase activity at a hydration degree 20 Á/25 (Rodakiewicz-Nowak et al, 2002;Rojo et al ., 2001;Sanchez-Ferrer et al ., 1995;Yang and Robb, 1993). Bearing in mind that tyrosinase is a tetramer, the existence of other tyrosinase forms, different from the tetramer always present in aqueous media, could be expected for the system of reverse micelles.…”

Section: Introductionmentioning

confidence: 99%

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Entrapping of Tyrosinase in a System of Reverse Micelles

Shipovskov

Levashov

2004

Biocatalysis and Biotransformation

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The enzymatic activity of tyrosinase was studied both in aqueous and organic media. In the latter case tyrosinase was entrapped in a system of reverse micelles of Aerosol OT in octane. At hydration degree 25, when the inner cavity of the reverse micelles was comparable with the size of a tetrameric tyrosinase form known for aqueous solutions, an optimum level of catalytic activity was observed. Another peak of catalytic activity of tyrosinase was observed at hydration degree 12, when the size of the inner cavity of the reverse micelles was consistent with a monomeric form of tyrosinase. Thus, the system of reverse micelles can be exploited as a medium for the investigation of the monomeric form of tyrosinase, which is unstable in aqueous solution.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Entrapping of Tyrosinase in a System of Reverse Micelles

Shipovskov

Levashov

2004

Biocatalysis and Biotransformation

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“…In another study, mushroom polyphenol oxidase was found to catalyze the oxidation of several phenols and catechols in AOT/cyclohexane reverse micelles (13). Catalytic efficiency of the enzyme was also related to substrate partitioning between the different microdomains of the system.…”

Section: Resultsmentioning

confidence: 95%

“…When the catalytic behavior of tyrosinase toward 4-methylcatechol was studied in AOT/cyclohexane reverse micelles, substrate inhibition was not observed (13). In addition, Yang and Robb (16) studied the oxidation catalyzed by tyrosinase of 4-methylcatechol and t-butylcatechol in AOT/isooctane and CTAB (hexadecyl trimethylammonium bromide)/hexane/chloroform reverse micelles.…”

Section: Resultsmentioning

confidence: 99%

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Olive oil microemulsions as a biomimetic medium for enzymatic studies: Oxidation of oleuropein

Papadimitriou

Sotiroudis

Xenakis

2005

J Americ Oil Chem Soc

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Microemulsions consisting of olive oil as the nonpolar solvent, lecithin as surfactant, 1-propanol as cosurfactant, and water were prepared. The choice of the compositions of the microemulsions used was based on the pseudo-ternary phase diagrams of the system determined at 30°C, for different weight ratios of lecithin/olive oil. Lecithin solubilization and water incorporation in these microemulsion systems was limited. Tyrosinase, an oxidizing enzyme present in olives, was successfully incorporated in the water core of these microemulsions. Enzymatic oxidation of oleuropein, the most abundant olive phenolic compound, in the restricted aqueous environment of olive oil microemulsions was studied. Formation of oleuropein oxidation products was followed spectrophotometrically at 30°C for several minutes. An absorption maximum was observed at 415 nm. When the enzymatic reaction was considered at different tyrosinase and oleuropein concentrations, a rapid inactivation of the enzyme was observed. Addition of L-proline as a coupling reactor did not succeed in preventing enzyme inactivation in the microemulsions, probably owing to substrate localization and product accumulation around the entrapped enzyme molecules in the micellar interface.Paper no. J10991 in JAOCS 82, 335-340 (May 2005).

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