Diglycosidases: a promising tool for the synthesis of tailored bioactive compounds

BRECCIA JD

Praga

Congreso; 10th Carbohydrate Bioengineering Meeting MultiGlycoNano; 2013

CAZY EU, Local organizers: Institute of Microbiology, Academy of Sciences of the Czech Republic & Congress Prague s.r.o.

Diglycosidases are enzymes that hydrolyze specifically the heterosidic linkage between a disaccharidic moiety and a non-sugar moiety. Their existence was suggested nearly nine decades ago by plant physiologists. However, only four diglycosidases that recognize and split off the disaccharides primeverose, acuminose, rutinose and vicianose were described in detail up to now [1]. The main interest has been placed on their unique substrate specificity for biotransformation of plant-based foods. In addition, these biocatalysts constitute an attractive tool for the synthesis of glycoconjugates because of their transglycosylation ability of disaccharide units. (Figure 1) At the moment, diglycosidases constitute an underexploited tool for glycosylation of organic intermediates. An illustrative example is the case of rhamnosylated drugs. Since L-rhamnopyranose origin is non-mammalian and rhamnose-capped drugs cannot be processed by the mammalian enzymes, such compounds could be exploited for drug delivery [2]. The synthesis of molecules containing exposed rhamnose residues constitutes a challenging task. α-Rhamnosidases (EC 3.2.1.40) exhibit an inverting mechanism, making rhamnosylation only possible by reverse hydrolysis or chemical synthesis. One way to overcome this problem was by means of the fungal diglycosidase α-rhamnosyl-β-glucosidase (EC 3.2.1.168), described for the first time by our group [3]. Under the appropriate conditions, the enzyme transglycosylated the disaccharide rutinose (6-O-α-L-rhamnosyl-D-glucose) to OH-acceptors in aqueous medium. Although with an extra arm of glucose, the process rendered Rha-capped drugs, avoiding reverse hydrolysis or sophisticated protection strategies of chemical synthesis. References [1] Mazzaferro & Breccia. 2011. Biocatal Biotransform 29:103?112 [2] Robinson et al. 2004. PNAS 101:14527?14532 [3] Mazzaferro et al., 2010. Arch Microbiol 192:383?393