Transglycosylation specificity of Acremonium sp. α-rhamnosyl-β-glucosidase and its application to the synthesis of the new fluorogenic substrate 4-methylumbelliferyl-rutinoside.

Transglycosylation reaction of endoxylanase from Trichoderma longibrachiatum

β-Glucosidases are reported to act in an exo manner and so are unable to hydrolyze the bond if another sugar is attached to a non-reducing terminus of glucose. However, endo-β-glucosidases recognizing the heterosidic linkage have been known to plant physiologists for eight decades, although they have been described in detail only recently. Because of the ability of these enzymes to split off a disaccharide they were named disaccharide-specific glycosidases or ‘diglycosidases’. In contrast to the sequential mechanism of two monoglycosidases, the transformation of some secondary metabolites in one step was reported as responsible for the production of toxic compounds involved in plant defense mechanisms against herbivores, such as hydrogen cyanide. The current focus of interest is on the application of their unique substrate specificity for biotransformation of plant-based foods. Four activities have been described and characterized so far, recognizing the following disaccharidic sugar moieties: pri...

Functional and biotechnological insights into diglycosidases

Most aroma compounds exist in vegetal tissues as disaccharide conjugates, rutinose being an abundant sugar moiety in grapes. The availability of aroma precursors would facilitate analytical analysis of plant-based foods. The diglycosidase α-rhamnosyl-β-glucosidase from Acremonium sp. DSM 24697 efficiently transglycosylated the rutinose moiety from hesperidin to 2-phenylethanol, geraniol, and nerol in an aqueous-organic biphasic system. 2-Phenethyl rutinoside was synthesized up to millimolar level with an 80% conversion regarding the donor hesperidin. The hydrolysis of the synthesized aroma precursors was not detected in an aqueous medium. However, in the presence of ethanol as a sugar acceptor, the enzyme was able to transfer the disaccharide residue forming the alkyl-rutinoside. The aroma precursors were significantly hydrolyzed (up to 3-4% in 2 h at 30 °C), which indicated the potential use of the enzyme for biotechnological applications, for example, in aroma modulation of fermented foods.

N. Kadi

Papers

Enzymatic synthesis of primeverosides using transfer reaction by Trichoderma longibrachiatum xylanase