The first, recently identified, archaealxylosidase from Sulfolobus solfataricus (XylS) shows high specificity for hydrolysis of isoprimeverose [a- -xylopyranosyl-(1,6)-D-glucopyranose, (X)], the p -nitrophenyl-a derivative of isoprimeverose, and xyloglucan oligosaccharides and has transxylosidic activity, forming, in a retaining mode, interesting a-xylosides. This article describes the synthesis of isoprimeverose, the disaccharidic repeating unit of xyloglucan, of thep-nitrophenyl-a 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 synthesis reactions of XylS, it being a biocatalyst (i) active hydrolytically only on X-ending substrates liberating a xylose molecule and (ii) capable of transferring xylose only on the nonreducing end glucose of p-nitrophenyl-(PNP)-a-D-cellobioside. The compounds synthesized by this enzyme are a starting point for enzymological studies of other new enzymes (i.e., xyloglucanases) for which suitable substrates are difficult to synthesize. This study also allows us to define the chemical characteristics of the xylose-transferring activity of this new archaeal enzyme,contributing to building up a library of different glycosidases with high specific selectivity for oligosaccharide synthesis.
Enzymatic synthesis and hydrolysis of xylogluco-oligosaccharides using the first archaeal a-xylosidase from Sulfolobus solfataricus
Trincone;
2001
Abstract
The first, recently identified, archaealxylosidase from Sulfolobus solfataricus (XylS) shows high specificity for hydrolysis of isoprimeverose [a- -xylopyranosyl-(1,6)-D-glucopyranose, (X)], the p -nitrophenyl-a derivative of isoprimeverose, and xyloglucan oligosaccharides and has transxylosidic activity, forming, in a retaining mode, interesting a-xylosides. This article describes the synthesis of isoprimeverose, the disaccharidic repeating unit of xyloglucan, of thep-nitrophenyl-a 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 synthesis reactions of XylS, it being a biocatalyst (i) active hydrolytically only on X-ending substrates liberating a xylose molecule and (ii) capable of transferring xylose only on the nonreducing end glucose of p-nitrophenyl-(PNP)-a-D-cellobioside. The compounds synthesized by this enzyme are a starting point for enzymological studies of other new enzymes (i.e., xyloglucanases) for which suitable substrates are difficult to synthesize. This study also allows us to define the chemical characteristics of the xylose-transferring activity of this new archaeal enzyme,contributing to building up a library of different glycosidases with high specific selectivity for oligosaccharide synthesis.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
