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Oxydation de composés phénoliques par les laccases de Trametes sp.  


Abstract Category: Science
Course / Degree: Procédés biotechnologiques et alimentaires
Institution / University: INSTITUT NATIONAL POLYTECHNIQUE DE LORRAINE, France
Published in: 2005


Thesis Abstract / Summary:

The oxidation of some phenolic compounds by laccase from Myceliophthora thermophila and Trametes sp. was studied in aqueous and hydro organic biphasic medium (ethyl acetate and phosphate buffer). In aqueous
medium and at the same pH, the two laccases give identical products. They have the same substrate
specificity but they show high affinity to phenolic compounds bearing methoxyl groups in particularly
ferulic and sinapic acid. In hydro organic biphasic medium, the rate of oxidation reaction that takes place in
the aqueous phase decreases steeply. Although at neutral pH the majority of phenolic substrates are soluble in the organic phase, the decrease of enzymatic activity is independent of the diffusional limitation. The hydro
organic biphasic medium doesnft modify the specificity of laccases but the intermediate products, which
polymerize quickly in aqueous medium, are prevented from doing so in biphasic medium due to their transfer
into the organic solvent. Therefore, their stability is enhanced in this medium. The oxidation of ferulic acid by
laccase from Myceliophthora thermophila in a biphasic hydro-organic system resulted in stable yellow intermediate products only soluble in the organic phase of this system.

We identified one of theses colored products as the decarboxyled 8-8L-ƒÁ-dehydro-lactone diferulate. The oxidation of sinapic acid causes the appearance of a red color in the two phases of the biphasic medium. The oxidation of phenolic compounds by the laccase in a biphasic hydro-organic medium illustrates an interesting potential significantly enhanced for preparation and separation of new colored products.


Thesis Keywords/Search Tags:
laccases, Myceliophthora thermophila, Trametes sp., oxidation, hydro-organic biphasic medium ferulic

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Submission Details: Thesis Abstract submitted by Rana Mustafa from France on 30-Nov-2008 20:50.
Abstract has been viewed 2636 times (since 7 Mar 2010).

Rana Mustafa Contact Details: Email: dr.ranamustafa@gmail.com



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