Identification of oligosaccharides formed during stachyose hydrolysis by Pectinex Ultra SP-L.

The commercial enzyme preparation Pectinex Ultra SP-L containing fructosyltransferase activity was used to hydrolyze stachyose. During this reaction, besides the formation of mono-, di-, and trisaccharides (DP(3)), the presence of one pentasaccharide (DP(5)) and a new oligosaccharide (DP(6)) has been detected by gas chromatography. DP(5) and DP(6) oligosaccharides were isolated and fully characterized for the first time by an extensive nuclear magnetic resonance (NMR) study. Complete structure elucidation and full proton and carbon assignments were carried out using 1D ((1)H, (13)C) and 2D (gCOSY, multiplicity-edited gHSQC, gHSQC-TOCSY, and gHMBC) NMR experiments. The two oligosaccharides were shown to be stachyose-based structures; the pentasaccharide has a fructose unit linked to the C-1 of the fructose end of stachyose, and the hexasaccharide has a fructose unit linked to the C-1 of the fructose end of the pentasaccharide. The fructosyltransferase activity present in Pectinex Ultra SP-L allows new uses of this commercial enzyme preparation in the synthesis of oligosaccharides derived from alpha-galactosides.