title: Electrospray ionization mass spectrometric analysis of κ-carrageenan oligosaccharides obtained by degradation with κ-carrageenase from Pedobacter hainanensis.
abstract: κ-Carrageenan was degraded with a novel κ-carrageenase isolated from Pedobacter hainanensis, which was first isolated from seaside soil under the stacks of red algae in Hainan province of China. The κ-carrageenase was detected with a molecular weight of ∼55 kDa estimated from SDS-PAGE and yielded enzymatic activity of 700.53 units/mg of protein under the conditions of pH 7.0 and 40 °C. Analysis of the degradation products by TLC and HPLC indicated that the enzyme degraded κ-carrageenan to sulfated oligosaccharides with even-numbered degree of polymerization, of which the tetrasaccharide was the major product. All the degradation components during different time courses were analyzed by ESI-MS, and their structures were assigned. Structural analysis by CID MS/MS revealed that each carrageenan oligosaccharide was composed of An-G4S-type neocarrabiose units, which consisted of a 3,6-anhydro-α-d-galactose (An) residue in the nonreducing end and a β-d-galactose-4-sulfate (G4S) residue in the reducing end. These results demonstrated that the κ-carrageenase cleaved κ-carrageenan at the internal β-1,4 linkage of κ-carrageenan. This enzymatic degradation offers an alternative approach to prepare κ-carrageenan oligosaccharides, which could be used as a powerful tool for further study on biological activity-structure relationship and thorough industrial exploitation of κ-carrageenan.
authors.affiliation: Educational Ministry Key Laboratory of Resource Biology and Biotechnology in Western China, Life Science College, Northwest University , Xi'an 710069, P. R. China.
authors.forename: Yujiao
authors.initials: Y
authors.lastname: Sun
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Kuan
authors.initials: K
authors.lastname: Jiang
authors.forename: Chengjian
authors.initials: C
authors.lastname: Wang
authors.forename: Zhongfu
authors.initials: Z
authors.lastname: Wang
authors.forename: Linjuan
authors.initials: L
authors.lastname: Huang
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification; D055162:Biocatalysis; D002351:Carrageenan / Q000737:chemistry* / Q000302:isolation & purification; D006026:Glycoside Hydrolases / Q000737:chemistry*; D009844:Oligosaccharides / Q000737:chemistry*; D060485:Pedobacter / Q000737:chemistry / Q000201:enzymology*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods
chemical_list: D001426:Bacterial Proteins; D009844:Oligosaccharides; D002351:Carrageenan; D006026:Glycoside Hydrolases