A. Jodelet et al., SEPARATION AND NMR STRUCTURAL CHARACTERIZATION OF SINGLY BRANCHED ALPHA-DEXTRINS WHICH DIFFER IN THE LOCATION OF THE BRANCH POINT, Carbohydrate research, 312(3), 1998, pp. 139-151
A series of singly branched a-dextrins with dp greater than or equal t
o 5 was prepared by treating amylopectin with an alpha-amylase (Termam
yl) and then with beta-amylase. The dextrins were separated by gel fil
tration chromatography and the composition of the fractions was checke
d by HPAEC. Each fraction gave essentially a single peak by HPAEC but
NMR spectroscopy indicated that only the fraction corresponding to dp5
consisted of one compound. The fractions corresponding to dp6, 7 and
8 were found to be mixtures of isomers. Three isomers of dp6 were sepa
rated by reversed phase HPLC and were characterised by NMR spectroscop
y. The isomers were identified as 6(2)-alpha-maltotriosyl-maltotriose,
6(3)-alpha-maltosyl-maltotetraose and 6(2)-alpha-maltosyl-maltotetrao
se. H-1 and C-13 NMR parameters of these compounds and of dp5, 6(2)-al
pha-maltosyl-maltotriose, are discussed in relation to the linkage pat
tern of the different glucose units and compared with similar paramete
rs in the linear maltodextrins. (C) 1998 Elsevier Science Ltd. All rig
hts reserved.