Improved quantitative analysis of oligosaccharides from lichenase-hydrolyzed water-soluble barley beta-glucans by high-performance anion-exchange chromatography.
Cereal beta-glucan is a linear biopolymer linked by beta-(1,3)/(1,4)-glycosidic bonds. More specifically, the beta-(1,4)-linked glucose chain is interrupted with beta-(1,3)-linkages in cereal beta-glucan structure. Elucidation of the exact length and distribution of linear beta-(1,4)-linked portion facilitates the understanding of the fine structure of cereal beta-glucan. A HPAEC assisted by lichenase treatment has been used for the structural and quantitative analysis of cereal beta-glucan. The absence of authentic standard oligosaccharides, putatively 3-O-beta-cellobiosyl-D-glucose (DP3) and 3-O-beta-cellotriosyl-D-glucose (DP4), was a potential problem to the characterization of beta-glucan structure. In this study, two major lichenase-hydrolyzed products were generated from the barley beta-glucan, and putative 3-O-beta-cellobiosyl-D-glucose and 3-O-beta-cellotriosyl-D-glucose were separated and highly purified by recycling preparative HPLC technology. Structural analysis of highly purified putative 3-O-beta-cellobiosyl-D-glucose and 3-O-beta-cellotriosyl-D-glucose was performed by TLC and LC-MS analysis. Two putative DP3 and DP4 displayed the nonreducing end/(1,4)/(1,3) linkage ratios of 1:0.96:0.90 and 1:2.18:1.16, respectively; the molecular masses (m/z) of their sodium adducts were 527.0 and 689.0, respectively. Using these structurally confirmed oligosaccharides, the exact amounts of beta-glucan lichenase hydrolysates from domestic barley cultivars were quantified. The amount of two major DP3 and DP4 accounted for only 71.4-73.3% of water-extractable beta-glucan fraction, and the (1,4)/(1,3) linkage ratios of the extracted beta-glucans were almost identical in the range of 2.24-2.25 among the barley cultivars tested.
Yoo
Dong-Hyung
DH
Department of Food Science and Technology, Sejong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747, Korea.
Lee
Byung-Hoo
BH
Chang
Pahn-Shick
PS
Lee
Hyeon Gyu
HG
Yoo
Sang-Ho
SH
D000838:Anions; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D006026:Glycoside Hydrolases / Q000378:metabolism*; D001467:Hordeum / Q000737:chemistry*; D006868:Hydrolysis; D009844:Oligosaccharides / Q000032:analysis*; D012639:Seeds / Q000737:chemistry; D012995:Solubility; D014867:Water; D047071:beta-Glucans / Q000737:chemistry* / Q000378:metabolism*
D000838:Anions; D009844:Oligosaccharides; D047071:beta-Glucans; D014867:Water; D006026:Glycoside Hydrolases; C028020:licheninase