Access to both anomers of rutinosyl azide using wild-type rutinosidase and its catalytic nucleophile mutant

Rutinosidases hydrolyze beta-rutinosylated flavonoids. As retaining glycosidases they also have a transglycosylation activity. Here we show that two newly identified wild-type rutinosidases, which are members of the glycoside hydrolase family 5-23, are capable of glycosylation of an inorganic azide with rutin as a glycosyl donor, yielding rutinosyl alpha-azide. On the other hand, rutinosyl beta-azide was synthesized by the catalytic nucleophile mutant of the rutinosidase from Aspergillus niger, which also belongs to GH5-23. Thus, we were able to synthesize at a preparatory scale both anomers of rutinosyl azide from rutin using either wild-type or mutant rutinosidases of GH5-23.