title: Structure of a shear-thickening polysaccharide extracted from the New Zealand black tree fern, Cyathea medullaris.
abstract: A shear-thickening water-soluble polysaccharide was purified from mucilage extracted from the fronds of the New Zealand black tree fern (Cyathea medullaris or 'mamaku' in Māori) and its structure characterised. Constituent sugar analysis by three complementary methods, combined with linkage analysis (of carboxyl reduced samples) and 1H and 13C nuclear magnetic resonance spectroscopy (NMR) revealed a glucuronomannan comprising a backbone of 4-linked methylesterified glucopyranosyl uronic acid and 2-linked mannopyranosyl residues, branched at O-3 of 45% and at both O-3 and O-4 of 53% of the mannopyranosyl residues with side chains likely comprising terminal xylopyranosyl, terminal galactopyranosyl, non-methylesterified terminal glucopyranosyl uronic acid and 3-linked glucopyranosyl uronic acid residues. The weight-average molecular weight of the purified polysaccharide was ∼1.9×10(6) Da as determined by size-exclusion chromatography coupled with multi-angle laser light scattering (SEC-MALLS). The distinctive rheological properties of this polysaccharide are discussed in relation to its structure.
authors: Institute of Food Nutrition and Human Health, Massey University, Private Bag 11 222, Palmerston North 4442, New Zealand.
authors: May S M
authors: MS
authors: Wee
authors: Institute of Food Nutrition and Human Health, Massey University, Private Bag 11 222, Palmerston North 4442, New Zealand.
authors: Lara
authors: L
authors: Matia-Merino
authors: The Ferrier Research Institute, Victoria University of Wellington, PO Box 33436, Petone, Lower Hutt 5046, New Zealand.
authors: Susan M
authors: SM
authors: Carnachan
authors: The Ferrier Research Institute, Victoria University of Wellington, PO Box 33436, Petone, Lower Hutt 5046, New Zealand.
authors: Ian M
authors: IM
authors: Sims
authors: Institute of Food Nutrition and Human Health, Massey University, Private Bag 11 222, Palmerston North 4442, New Zealand. Electronic address: K.T.Goh@massey.ac.nz.
authors: Kelvin K T
authors: KK
authors: Goh
mesh_terms: D029624:Ferns / Q000737:chemistry*; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D010936:Plant Extracts / Q000737:chemistry* / Q000302:isolation & purification; D011134:Polysaccharides / Q000737:chemistry* / Q000302:isolation & purification; D012212:Rheology
chemical_list: D010936:Plant Extracts; D011134:Polysaccharides
keywords: Cyathea medullaris; Glucuronomannan; NMR; Rheology; Structural analysis