title: Sequence determination of a non-sulfated glycosaminoglycan-like polysaccharide from melanin-free ink of the squid Ommastrephes bartrami by negative-ion electrospray tandem mass spectrometry and NMR spectroscopy.
abstract: A non-sulfated polysaccharide was isolated from the ink sac of squid Ommastrephes bartrami after removal of the melanin granules. The carbohydrate sequence of this polysaccharide was assigned by negative-ion electrospray tandem mass spectrometry with collision-induced dissociation of the oligosaccharide fractions produced by partial acid hydrolysis of the polysaccharide. The structural determination was completed by NMR for assignment of anomeric configuration and confirmation of linkage information and it was unambiguously identified as a glycosaminoglycan-like polysaccharide containing a glucuronic acid-fucose (GlcA-Fuc) disaccharide repeat in the main chain and a N-acetylgalactosamine (GalNAc) branch at Fuc position 3: -[3GlcAbeta1-4(GalNAcalpha1-3)Fucalpha1](n)-. Partial hydrolysis of the polysaccharide to obtain several oligosaccharide fractions with different numbers of the repeating unit assisted the assignment. In the negative-ion tandem mass spectrometric analysis, the unique (0,2)A type fragmentation was important to establish the presence of a 4-linked fucose in the main polysaccharide chain and a GalNAc branch at the Fuc position-3 of the disaccharide repeat.
authors.affiliation: College of Food Science and Technology, Ocean University of China, Qingdao, Shandong, China.
authors.forename: Shiguo
authors.initials: S
authors.lastname: Chen
authors.forename: Jie
authors.initials: J
authors.lastname: Xu
authors.forename: Changhu
authors.initials: C
authors.lastname: Xue
authors.forename: Ping
authors.initials: P
authors.lastname: Dong
authors.forename: Wenjing
authors.initials: W
authors.lastname: Sheng
authors.forename: Guangli
authors.initials: G
authors.lastname: Yu
authors.forename: Wengang
authors.initials: W
authors.lastname: Chai
mesh_terms: D000818:Animals; D002240:Carbohydrate Sequence; D005591:Chemical Fractionation; D002850:Chromatography, Gel; D049832:Decapodiformes / Q000737:chemistry*; D006025:Glycosaminoglycans / Q000032:analysis / Q000737:chemistry* / Q000302:isolation & purification; D007281:Ink; D009682:Magnetic Resonance Spectroscopy; D008543:Melanins / Q000378:metabolism*; D008969:Molecular Sequence Data; D009005:Monosaccharides / Q000032:analysis / Q000737:chemistry; D009844:Oligosaccharides / Q000032:analysis / Q000737:chemistry; D017421:Sequence Analysis; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D006025:Glycosaminoglycans; D008543:Melanins; D009005:Monosaccharides; D009844:Oligosaccharides