Digestion by fungal glycanases of arabinoxylans with different feruloylated side-chains.
Alcohol-insoluble residues (AIRs) from Festuca and Zea cell cultures contained 7.4 and 35 nmol esterified ferulate mg-1, respectively. Driselase solubilised 79% of the feruloylated material from both AIRs. Of the feruloyl esters solubilised from Festuca and Zea AIRs, 72 and 56% respectively were small enough to be mobile on paper chromatography. The major feruloylated product of Zea AIR was the known 5-O-feruloyl-alpha-L-Araf-(1-->3)-beta-D-Xylp-(1-->4)- D-Xyl (Fer-Ara-Xyl-Xyl). In contrast, the smallest major feruloylated product of Festuca AIR was a feruloyl pentasaccharide (3) containing 3 Xyl, 1 Ara and 1 non-pentose residue (NPR). The Ara and two of the three Xyl groups of 3 were resistant to NaIO4. Mild acid hydrolysis of 3 gave xylobiose, a feruloyl trisaccharide and beta-D-Xylp-(1-->2)-(5-O-feruloyl)-L-Ara. Compound 3 was therefore NPR-(1-->3)-beta-D-Xylp-(1-->2)-(5-O-feruloyl)-alpha-L-Ar af-(1-->3)-beta-D-Xylp-(1-->4)-D-Xyl. We conclude that the complex feruloyl oligosaccharide side-chains of Festuca arabinoxylan do not protect the polysaccharide against hydrolysis by the fungal glycanases present in Driselase.
Wende
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ICMB, DBS, University of Edinburgh, U.K.
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D001487:Basidiomycota / Q000201:enzymology*; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002478:Cells, Cultured; D003373:Coumaric Acids; D006026:Glycoside Hydrolases / Q000378:metabolism*; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism*; D006109:Poaceae; D013379:Substrate Specificity; D014990:Xylans / Q000737:chemistry / Q000378:metabolism*; D003313:Zea mays
D003373:Coumaric Acids; D009844:Oligosaccharides; D014990:Xylans; C004999:ferulic acid; D006026:Glycoside Hydrolases