Abstract:

To acquire the mechanism of lentinan hydrolysis and full series of gluco-oligosaccharides from hydrolyzed lentinan, the hydrolysis time of lentinan treated with 0.02 mol/L trifluoroacetic acid(TFA) at 100 ℃ was optimized through analysis the distribution of different degree of polymerization(DP) oligosaccharides at 2, 4, and 6 h. And then lentinan hydrolysis was repeated another three times until no precipitation can be observed under optimal hydrolysis time. The mass spectrometry character of 7-mer oligosaccharides from all the four batch hydrolysis products was analyzed using ESI-CID-MS/MS based on the mass spectrometry character of 7-mer β-1,3-and β-1,6-gluco-oligosaccharides, and acquiring a hydrolysis mechanism. Finally, all the four batch hydrolysis products were combined and separated with P4 column and full series of gluco-oligosacchaides from 2-mer to 13-mer were acquired. The optimal time for lentinan hydrolysis was 4 h, and β-1,3/1,6-gluco-oligosaccharides in hydrolysis lentinan was observed at the first batch, and then the amount of β-1,3/1,6-gluco-oligosaccharides reduced with the increasing of hydrolysis times, and there only observed β-1,3-gluco-oligosaccharides at the fourth hydrolysis products. This results also suggested that the triple helix structure zone containing β-1,3/1,6-linkage of lentinan is loose, but the only containing β-1,3-linkage triple helix structure zone in lentinan is tight. The theory acquired in this work will supply useful information for preparation gluco-oligosaccharides in large-scale and it also expand the gluco-oligosaccharides library for exploring protein-carbohydrate interaction using carbohydrate microarray.

Key words: Lentinan, Gluco-oligosaccharide, Mechanism of hydrolysis, Electrospray ionization-collision induce dissociation-tandem mass spectrometry(ESI-CID-MS/MS)