Oxidation of Polysaccharides by Galactose Oxidase

Abstract

Galactose oxidase was used as a catalyst to oxidize selectively the C-6 hydroxyls of terminal galactose to carbonyl groups. The polysaccharides studied included spruce galactoglucomannan, guar galactomannan, larch arabinogalactan, corn fiber arabinoxylan, and tamarind seed xyloglucan, with terminal galactose contents varying from 6% to 40%. A multienzyme system was used, with catalase and horseradish peroxidase to enhance the action of galactose oxidase. An analysis technique was developed for the quantification of the reactive aldehydes with GC-MS, utilizing NaBD4 reduction and acidic methanolysis. The best oxidation degrees of terminal galactosyls were obtained with xyloglucan (85% of galactose) and spruce galactoglucomannan (65% of galactose). The highest oxidation degree based on total carbohydrates was achieved with guar gum (28%), which had the highest galactose content. The oxidation resulted in changes in the physicochemical properties of the polysaccharide solutions, and the changes observed varied between the polysaccharides. The clearest change was in tamarind xyloglucan, which formed a gel after the oxidation. After the oxidation, larger particles were present in the solution of spruce galactoglucomannan, but changes in its rheological properties were not observed.

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

“…: depolymerization with carbohydrolases or lyases (Cheroni, Formantici, & Galante, 2010;Delattre et al, 2015;Tavernier et al, 2008), debranching with ␣-glycosidase, oxidation with oxidases (i.e., laccase, peroxidase, galactose oxidase), but also for the "elimination" of insoluble proteins with proteases (Baldaro et al, 2012). 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).…”

Multi-layer nanopaper based composites

“…Hydrolyzed GG was enzymatically oxidized (OGG) whereby the dosage of the enzymes was based on the amount of galactose present in the GG sample: 1.50 units (U) of GO, 150 U of catalase and 0.9 U of HRP per mg of galactose (Lucenius et al 2014;Parikka et al 2010). 1% (w/v) solutions of GG were stirred in the presence of the enzymes at ?4°C for 72 h. Afterwards the sample was heated to 90°C while mixing in order to inactivate the enzymes.…”

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].…”