fulltext.study @t Gmail

Oxidation of galactomannan by laccase plus TEMPO yields an elastic gel

Paper ID Volume ID Publish Year Pages File Format Full-Text
23841 43477 2011 9 PDF Available
Title
Oxidation of galactomannan by laccase plus TEMPO yields an elastic gel
Abstract

Chemical modifications of galactomannans are applied to improve and/or modify their solubility, rheological and functional properties, but have limited specificity and are often difficult to control. Enzymatic reactions, catalyzed under mild process conditions, such as depolymerization, debranching and oxidation, represent a viable and eco-friendly alternative. In this study, we describe oxidation of guar galactomannan primary hydroxyl groups by a fungal laccase using the stable radical TEMPO as mediator. Four fungal laccases were investigated from: Trametes versicolor, Myceliophthora thermophila, Thielavia arenaria, Cerrena unicolor. The laccase from T. versicolor was found to efficiently oxidize TEMPO and to be free of mannanase side activity. Oxidation of galactomannan with this enzyme plus TEMPO brought about a ten-fold increase in viscosity of a guar galactomannan solution and altered its rheological profile, by converting a viscous polysaccharide solution into an elastic gel. This structural modification is presumably due to formation of inter-chain hemiacetalic bonds between newly generated carbonyl groups and free OH groups, yielding a cross-linked gel. These findings could be of practical importance, considering that polysaccharides with high viscosity, gelling and elastic properties can find interesting and novel applications as thickeners, viscosifiers and emulsion stabilizers in several industrial applications such as: personal care, oil operations, paper coating, paints, construction and mining.

► A fungal laccase oxidizes primary hydroxyls of galactomannans with TEMPO as mediator. ► Four different laccases were characterized to select the most suitable enzyme. ► The laccase from T. versicolor oxidizes galactomannan, generating an elastic gel. ► This modification is likely due to formation of inter-chain hemiacetalic bonds. ► Polysaccharides with high viscosity and elastic properties could find several uses.

Keywords
ABTS, 2,2′-azino-bis(3-ethyl-benzothiazoline-6-sulphonic acid); GO, galactose oxidase; Lcc, laccase; LMS, laccase mediator system; SDS-PAGE, sodium dodecylsulfate polyacrylamide gel electrophoresis; TEMPO, 2,2,6,6-Tetramethyl-1-piperidinyloxy radical; TLC
First Page Preview
Oxidation of galactomannan by laccase plus TEMPO yields an elastic gel
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us
Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Biotechnology - Volume 156, Issue 2, 10 November 2011, Pages 108–116
Authors
, , , , , ,
Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us