Oxidation of galactomannan by laccase plus TEMPO yields an elastic gel

An aerogel obtained from chemo-enzymatically oxidized fenugreek galactomannans as a versatile delivery system

“…We have previously reported (Lavazza et al, 2011) that a fungal laccase from Trametes versicolor (benzene-diol: oxygen oxidoreductase, E.C. 1.10.3.2, see Riva, 2006;Rodgers et al, 2010;Witayakran & Ragauskas, 2009), in combination with the mediator TEMPO for laccase regeneration (Bragd, van Bekkum, & Besemer, 2004), oxidizes primary hydroxyl groups of GM in an unbuffered aqueous solution of guar galactomannan, causing a substantial viscosity increase of the polysaccharide solution, which is converted to an elastic gel, as confirmed by its modified rheological profile.…”

“…In the first step, primary hydroxyl groups of FG galactose residues are chemo-oxidized to carbonyls by the laccase/TEMPO catalytic system (Lavazza et al, 2011;Merlini et al, 2015). In the reaction, TEMPO is firstly oxidized to an oxoammonium ion, which in turn selectively oxidizes primary OH's to the corresponding aldehydes (see also : Ding et al, 2008;Marzorati, Danieli, Haltrich, & Riva, 2005;.…”

“…Enzymatic oxidation of guar GM has been described using either a wild type galactose oxidase (GaO), followed by reductive amination (Hall & Yalpani, 1980) or by halogen oxidation (Frollini, Reed, Milas, & Rinaudo, 1995), or with a highly engineered GaO by Parikka and co-workers (Delagrave et al, 2001(Delagrave et al, , 2002Ghafar et al, 2015;Leppanen et al, 2010;Mikkonen et al, 2014;Parikka & Tenkanen, 2009;Parikka et al, 2010Parikka et al, , 2012Parikka, Master, & Tenkanen, 2015). More generally, oxidation of polysaccharides with the enzyme laccase can generate reactive groups (e.g., carbonyls, carboxyls) on cellulose , on starch (Viikari, Niku-Paavola, et al, 1999), on pullulan (Jetten et al, 2000), and on guar galactomannan (Lavazza et al, 2011).…”

Enzyme-Catalyzed Modifications of Polysaccharides and Poly(ethylene glycol)

“…This structure was shown to improve the dry strength of paper [56][57][58][59]. Other enzymes have also been reported to carry out this oxidation [60,61].…”

Quantification of Sugar Epimers in Polygalactomannans by ESI-MS/MS

“…The interest in these polymers is mainly due to the possibility of obtaining solutions with unique rheological properties, like extreme viscosities and nonNewtonian behavior [13][14][15]. PGMs are often subjected to chemical reactions (e.g., hydroxyalkylation, carboxymethylation) [16,17] or enzymatic treatments (e.g., depolymerization by β-mannanase, oxidation by laccase or galactose oxidase) [18][19][20], in order to modify their solubility and viscoelastic properties, or to obtain hybrid, functionalized materials [21,22].…”