1 Department of Chemistry, Technical University of Denmark2 Organic Chemistry, Department of Chemistry, Technical University of Denmark3 University of Iceland4 Carlsberg Laboratory5 University of Oslo6 Center for Hyperpolarization in Magnetic Resonance, Center, Technical University of Denmark7 University of Iceland
Two galactofuranomannans, Ths-4 and Ths-5, were isolated from the lichen, Thamnolia vermicularis var. subuliformis, using ethanol fractionation and anion-exchange and size-exclusion chromatography. The average molecular weights of Ths-4 and Ths-5 were estimated to be 19 and 200 kDa, respectively. Structural characterisation of Ths-4, Ths-5 and their partially hydrolysed derivatives was performed by methanolysis and methylation analysis. The intact and partially hydrolysed Ths-4 was further analysed using NMR spectroscopy (1D, COSY, NOESY, TOCSY, HSQC and HMBC). According to the data obtained, the heteroglycans Ths-4 and Ths-5 have similar structures, but have large differences in molecular weight. The structure is composed of 3-O-linked and 5-O-linked galactofuranosyl chains linked to a mannan core. The mannan core consists of a main chain of alpha-(1 -> 6)-linked mannopyranosyl residues, substituted at O-2 with either a single alpha-mannopyranosyl unit or an alpha-Manp-(1 -> 2)-alpha-Manp-(1 -> 2)-alpha-Manp group in the ratio of approximately 1:3, respectively. The polysaccharides have idealised repeating blocks as is shown. (c) 2006 Elsevier Ltd. All rights reserved.
Carbohydrate Research, 2006, Vol 341, Issue 14, p. 2449-2455