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Sammanfattning

Mixed-linkage beta-glucan from barley, with a cellotriosyl to cellotetraosyl ratio of 2.9, was hydrolysed with two endo-1,4-beta-glucanases (cellulases) and one non-cellulolytic P-glucanase isolated from Trichoderma reesei. The hydrolysates were precipitated in 90% ethanol and the fragments obtained were further treated with lichenase, followed by analysis of the oligosaccharides released. One of the endo-1,4-beta glucanases, Cel 5A (EG II), selectively degraded cellotetraosyl units in the polymer and left the cellotriosyl units unhydrolysed. Blocks of cellotriosyl units were isolated on a larger scale using this enzyme. The isolated blocks were fractionated into four fractions using gel permeation chromatography on Biogel P-6 and the structures of the blocks were analysed by H-1 NMR spectroscopy. The fractions essentially contained cellotriosyl units of different sizes with a 3-linked glucose residue at the non-reducing end and a reducing end linked to two 4-linked glucose residues. The results thus indicated that the enzyme could hydrolyse a 4-linked glucose residue next to the 3-linked residue at the non-reducing terminal but left two 4-linked glucose residues at the reducing end. The isolated blocks of cellotriosyl units had a molecular weight distribution that fits a theoretical model based on random blocks of triosyl units in the mixed-linkage beta-glucan. (c) 2005 Elsevier Ltd. All rights reserved.

Nyckelord

barley beta-glucan; cellotriosyl blocks; endo-glucanase

Publicerad i

Carbohydrate Polymers
2006, volym: 64, nummer: 2, sidor: 233-238

SLU författare

UKÄ forskningsämne

Livsmedelsvetenskap

Publikationens identifierare

  • DOI: https://doi.org/10.1016/j.carbpol.2005.11.033

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/10412