STRUCTURAL ANALYSIS BY MASS SPECTROMETRY OF OLIGOSACCHARIDES RELATED TO XYLANS

Article abstract of DOI:10.1016/S0008-6215(00)85533-0

Fully methylated, xylan-type oligosaccharides, namely, positionally and interglycosidically isomeric O-D-xylopyranosyl-β-D-xylopyranoses ( xylobioses, 2-7 ), a complete series of O-β-D-xylopyranosyl(1->4)-O-β-D-xylopyranosyl-β-D-xylopyranoses ( xylotrioses, 8, 9, 11, 12 and 14 ), a branched β-D-xylotetraose ( 15 ), and α-D-xylopyranosyl β-D-xylopyranoside ( 1 ), have been studied by 70- and 12 eV mass spectrometry.By using high-resolution techniques metastable-transition measurements, ion species formed through hirherto unknown fragmentation-processes have been found for the ( 1->1 )- and ( 1->3 )-linked disaccharides 1,4, and.Based on the qualitative and quantitative differences in the fragmentations, criteria for unambiguous determination of the positional mode of linkage in xylobioses are proposed.Similarly, by studying the fragmantation of xylotriose ( 10 ) labelled in the side-chain with trideuteriomethyl groups, the fragmentation-pathways for xylotrioses have been clarified.A new fragmentation series has been discovered in the fission of trioses 13 and 14 having a D-xylopyranosyl group attached to )-O-3 of the nonreducing end of the basic ( 1->4 )-linked skeleton.Within the series of di- and tri-saccharides studied, the criteria proposed permit reliable determination of any of the theoretically possible branching points.The basic possibilities for structural analysis by mass spectrometry of related pentose tetroses are also shown.