Ja. Stjohn et al., IDENTIFICATION OF PRODUCTS FORMED BY A FRUCTAN-FRUCTAN FRUCTOSYLTRANSFERASE ACTIVITY FROM LOLIUM-RIGIDUM, New phytologist, 135(2), 1997, pp. 249-257
The products formed by a fructan:fructan fructosyltransferase (FFT) ac
tivity purified from Lolium rigidum Gaudin were identified after gas c
hromatography-mass spectrometry of partially methylated alditol acetat
es, electrospray ionization-mass spectrometry and reversed-phase high-
performance liquid chromatography. The FFT activity synthesized oligof
ructans up to degree of polymerization (DP) 6, but did not synthesize
fructans of DP > 6 even when assayed with (1,1,1)-kestopentaose for up
to 10 h. The FFT activity when assayed with 1-kestose or 6(G)-kestose
synthesized fructan with fructosyl residues almost exclusively linked
by beta-2,1-glycosidic linkages. When assayed with 1-kestose, the FFT
activity synthesized tetrasaccharides and pentasaccharides with an in
ternal glucosyl residue. The predominant tetrasaccharide was (1&6(G))-
kestotetraose and the predominant pentasaccharide was (1&6(G),1)-kesto
pentaose. By comparison, tetrasaccharides and pentasaccharides extract
ed from L. rigidum also contained predominantly beta-2,1-glycosidic li
nked fructans with an internal glucosyl residue. The only exception wa
s that one of the pentasaccharides contained beta-2,1- and beta-2,6-gl
ycosidic linked fructosyl residues. This pentasaccharide was not synth
esized by the FFT activity. The role of this FFT activity in formation
of oligofructans in L. rigidum is discussed.