Cereal Chem. 71:301-307   |  VIEW ARTICLE


Structural Studies of (1-3)(1-4)-beta-D-Glucans by 13C-Nuclear Magnetic Resonance Spectroscopy and by Rapid Analysis of Cellulose- Like Regions Using High-Performance Anion- Exchange Chromatography of Oligosaccharides Released by Lichenase.

P. J. Wood, J. Weisz, and B. A. Blackwell. Copyright 1994 by the American Association of Cereal Chemists, Inc. 

The structures of (1-3)(1-4)-beta-D-glucans (beta-glucans) were evaluated by high-performance anion- exchange chromatography (HPAEC) of the oligosaccharides produced by the action of (1-3)(1-4)-beta-D- glucan-4-glucanohydrolase (lichenase; EC 3.2.1.73). The relative amounts of the released oligosaccharides constitute a fingerprint of structure, and the method is particularly useful for identification of minor, cellulose-like features in the polysaccharides. In general, the cereal beta-glucans were similar, but the ratio of (1-3)-linked cellotriosyl to (1-3)-linked cellotetraosyl units, which constituted approximately 90% of the polysaccharides, was lower for oats (2.1-2.4) than it was for barley and rye (2.8-3.3). A portion (3-4%) of oat and barley beta-glucan was rendered water-insoluble by lichenase. HPAEC revealed that these products, shown by 13C-nuclear magnetic resonance spectroscopy to be cellulose-like, were composed of oligosaccharides of degree of polymerization 9-15. Lichenan is distinct from cereal beta-glucans, being mainly (1-3)-linked cellotriosyl units. No evidence for consecutive (1-3)-linkages was found in any of the beta-glucans. The extractability of oat and barley beta-glucan was not related to identifiable structural differences. Oat aleurone beta-glucan has less of the (1-3)-linked cellotetraosyl units than did endospermic beta-glucan.