Xylan-cellulose core structure of oat water-extractable β-glucan macromolecule: Insight into interactions and organization of the cell wall complex

• Published in: Carbohydrate polymers 2024-01, Vol.324 (C), p.121522-121522, Article 121522
• Main Authors: Cyran, Małgorzata R., Snochowska, Krzysztofa K., Potrzebowski, Marek J., Kaźmierski, Sławomir, Azadi, Parastoo, Heiss, Christian, Tan, Li, Ndukwe, Ikenna, Bonikowski, Radosław
• Format: Article
• Language: English
• Subjects: Arabinoxylan; CP/MAS 13C NMR; Ferulic acid; Multi-detection HPSEC; Oat (Avena sativa L.); β-Glucan
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2023.121522

Water-extractable β-glucan with high molar mass (HM) determines health benefits of oat food. Oat β-glucan was extracted by a standardized in vitro digestion method and co-existing water-extractable polysaccharide (WEP) fraction and its HM-arabinoxylan (HM-AX) subfraction were isolated to identify their highly acid-resistant subunit and investigate molecular interactions between constituent polymers. The WEP and HM-AX samples consisted of arabinoxylans (AXs) (74 and 76 %, respectively), however, cellulose constituted the secondary component (6.6 and 12.8 %, respectively). Multi-detection HPSEC along with specific enzymatic hydrolysis of AXs revealed the presence of the HM-xylan domain (16 and 34 %, respectively) built of numerous single- and multi-component populations with random coil and rod-like conformations, which were embedded in a xylan matrix with spherical conformation and controlled the macromolecular shape. Unlike single-component populations, the multi-component ones were resistant to hydrolytic action of AX-hydrolyzing enzymes and represented the subunits that anchor matrix polysaccharides onto cellulose surface. These results indicate that water-extractable β-glucan macromolecule comprises as integral element a cellulose core with two linking populations, HM-xylan and low molar mass glucomannan, which are surrounded by a feruloylated AX-arabinan-arabinogalactan composite and next laminated by β-glucan matrix. The stiff cellulose-xylan backbone is the basis of HM β-glucan organization, controlled by its cellulose-like segments. [Display omitted]