A. Trincone et al., Enzymatic synthesis and hydrolysis of xylogluco-oligosaccharides using thefirst archaeal alpha-xylosidase from Sulfolobus solfataricus, EXTREMOPHIL, 5(4), 2001, pp. 277-282
The first, recently identified, archaeal alpha -xylosidase from Sulfolobus
solfataricus (XylS) shows high specificity for hydrolysis of isoprimeverose
[alpha -D-xylopyranosyl-(1,6)-D-glucopyranose, (X)], the p-nitrophenyl-bet
a derivative of isoprimeverose, and xyloglucan oligosaccharides and has tra
nsxylosidic activity, forming, in a retaining mode, interesting alpha -xylo
sides. This article describes the synthesis of isoprimeverose, the disaccha
ridic repeating unit of xyloglucan, of the p-nitrophenyt-beta derivative of
isoprimeverose, and of a trisaccharide based on isoprimeverose that is one
of the trisaccharidic building blocks of xyloglucan. A substrate structure
-activity relationship is recognized for both the hydrolysis and the synthe
sis reactions of XylS, it being a biocatalyst (i) active hydrolytically onl
y on X-ending substrates liberating a xylose molecule and (ii) capable of t
ransferring xylose only on the nonreducing end glucose of p-nitrophenyl-(PN
P)-beta -D-cellobioside. The compounds synthesized by this enzyme are a sta
rting point for enzymological studies of other new enzymes (i.e., xylogluca
nases) for which suitable substrates are difficult to synthesize. This stud
y also allows us to define the chemical characteristics of the xylose-trans
ferring activity of this new archaeal enzyme, contributing to building up a
library of different glycosidases with high specific selectivity for oligo
saccharide synthesis.