Analysis of structural heterogeneity of κ/β-carrageenan oligosaccharides from Tichocarpus crinitus by negative-ion ESI and tandem MALDI mass spectrometry

A mixture of oligosaccharides, released with enzymatic digestion from kappa/beta-carrageenan of the red seaweed Tichocarpus crinitus was investigated. The composition, sequence and sulfation pattern of the oligosaccharide mixture were elucidated by negative-ion electrospray ionization and MALDI potential lift tandem TOF mass spectrometry. It was shown, that oligosaccharide mixture (DP up to 20), produced by kappa-carrageenase, contained kappa-carrabiose, kappa-carratetraose as main components, and set of hybrid oligosaccharides as less abundant components: beta -> kappa, kappa -> beta -> kappa, beta -> kappa -> kappa, and minor beta -> iota -> kappa, beta -> beta -> kappa -> kappa, beta -> kappa -> beta -> kappa, kappa -> beta -> beta -> kappa, kappa -> beta -> kappa kappa -> beta -> beta -> beta -> kappa, beta -> beta -> kappa ->beta -> beta, kappa -> beta -> kappa -> beta -> kappa, kappa -> beta -> beta kappa -> kappa. The application of arabinoosazone as a MALDI matrix for negative-ion mode with the addition of L-fucose allowed decreasing the in-source fragmentation. The oligosaccharides of kappa/beta-carrageenan were shown to maintain an ability to induce of TNF-alpha and IL-6 secretion of immune cells. (C) 2011 Elsevier Ltd. All rights reserved.