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Fig. 8 (a) Glycosynthase,
(b) Thioglycoligase and (c)
thioglycosynthase enzymatic
mechanisms.
oligosaccharide synthesis. Further improvements on Abg glycosynthases
were obtained by replacement of glutamate residue by a Serine, instead of
Alanine.
73
Since those tremendous advances, glycosynthase approach has been
extended on several glycosidases,
74
broadly reviewed,
45,75-79
and is still
under investigations to provide e
cient biocatalysts for scaled-up pur-
poses. The wide variety of glycosynthases actually available allows access
to diverse glycoderivatives, form simple carbohydrates to neoglyco-
conjugates as well as short to high polymeric degree oligosaccharides,
confirming that bio-engineered glycosidases are powerful tool for glyco-
diversification. In addition, the development of glycosynthases has paved
the way to the conception of the thioligases.
2.2.3 Thioglycoligases & thioglycosynthases. As described earlier in
this chapter, thioglycosides are naturally occurring entities and possess,
thanks to their S-glycosidic linkage, remarkable properties such as re-
sistance through enzymatic cleavage that make them interesting targets
for therapeutic purposes.
80
While thioglycosides synthesis through
chemical routes have been extensively studied and reported in numerous
reviews,
81,82
enzymatic methods were neglected despite their advantages:
i) inherent regio-control of the glycosidic linkages, ii) mild reaction
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