Sequencing analysis of b-glucan from highland barley with high performance anion exchange chromatography coupled to quadrupole time e Of e Flight mass spectrometry

Highland barley is one of the hull-less barleys that contains high amounts of b-glucan. A detailed sequence analysis is needed to support the application of the b-glucan from highland barley. The bconformation and 1 / 3/1 / 4 linkages were confirmed using nuclear magnetic resonance (NMR) spectroscopy. Monosaccharide analysis was accomplished with high-performance anion exchange chromatography (HPAEC) coupled to pulsed amperometric detection (PAD) and showed that glucose (G) was the dominant sugar component of this b-glucan. HPAEC-PAD was applied with on-line electrospray ion to quadrupole time e of e flight mass spectrometry (Q/TOF-MS) to sequence oligosaccharides enzymatically derived from this b-glucan. More than 20 oligosaccharides were observed in the partially digested b-glucan mixture and their degree of polymerization (dp), confirmed by MS analysis, ranged from dp 2 to dp 20. The sequences of oligosaccharide dp2 e dp7 in the digested product mixture were unambiguously determined with MS/MS. Based on the sequence analysis of these oligosaccharides, G1/3G1/4G and G1/3G1/4G1/4G were determined to be the major repeating blocks of this bglucan, and they were interspersed with homogeneous 1/ 4 linked domains with different lengths. The ratio of 1 / 3 and 1 / 4 linkages in the b-glucan was approximately 1:3. © 2017 Elsevier Ltd. All rights reserved.