earticle

영어

Retaining glycosidases, which are originally glycoside hydrolases, are efficient synthetic catalysts for the assembly of glycosides. However, yields of the transglycosylation reactions are typically low due to hydrolysis of the transfer product. A class of mutant glycosidase termed glycosynthase that largely obviates this hydrolytic problem by lacking of the catalytic nucleophile, thus the ability to form a reactive glycosyl enzyme intermediate, is complemented by the use of glycosyl fluorides of opposite stereochemistry to that of the natural substrates as donor sugars. While these strategies have proved to work well for β-glycosidases, their application to α-glycosidases has been less successful.
Thus, for α-glycosynthases, only two examples derived from retaining α-glycosidases have been published, along with one from an inverting α -glycosidase. Recently, it was found that an α-xylosidase mutant that lacks its acid/base residue performs efficiently and regioselective transglycosylation reactions using α-xylosyl fluoride as a donor in yields of over 95%. It will be interesting to see how generally applicable this acid/base muation strategy turns out to be to α-glycosidases