caa a22 4500 477100317 CHVBK 20180405111539.0 cr unu---uuuuu 170330e19961001xx s 000 0 eng 10.1007/BF00208312 doi (NATIONALLICENCE)springer-10.1007/BF00208312 Substrate subsite recognition of the xyloglucan endo -transglycosylase or xyloglucan-specific endo -(1→4)-β- d -glucanase from the cotyledons of germinated nasturtium ( Tropaeolum majus L.) seeds [Elektronische Daten] [Cristina Fanutti, Michael Gidley, J. Reid] We have investigated the substrate subsite recognition requirement of the xyloglucan endo-transglycosylase/xyloglucan-specific endo-(1→4)-β-d-glucanase (NXET) from the cotyledons of nasturtium seedlings. Seed xyloglucans are composed almost entirely of the Glc4 subunits XXXG, XLXG, XXLG and XLLG, where G represents an unsubstituted glucose residue, X a xylose-substituted glucose residue and L a galactosyl-xylose-substituted glucose residue. Thus in the xyloglucan sequence shown below, the xylose (Xyl) residues at the backbone glucose (Glc) residues numbered — 3,— 2, + 2 and + 3 may be galactose-substituted, and NXET cleaves between the unsubstituted glucose at — 1 and the xylose-substituted glucose at + 1, which never carries a galactosyl substituent. We have isolated the xyloglucan oligosaccharides XXXGXXXG and XLLGXLLG from NXET digests of tamarind seed xyloglucan, have modified them enzymatically using a pure xyloglucan oligosaccharide-specific α-xylosidase from nasturtium seeds to give GXXGXXXG and GLLGXLLG, and have identified and compared the products of NXET action on XXXGXXXG, GXXGXXXG, XLLGXLLG and GLLGXLLG. We have also compared the molar proportions of XXXG, XLXG, XXLG and XLLG in native tamarind and nasturtium seed xyloglucans with those in NXET digests of these polysaccharides. Using these and existing data we have demonstrated that NXET action does not require xylosesubstitution at glucose residues — 4, — 2, + 1 and + 3 and that xylose substitution at + 2, is a requirement. There may also be a requirement for xylose substitution at — 3. We have demonstrated also that galactosyl substitution of a xylose residue at + 1 prevents, and at — 2 modifies, chain-cleavage. A partial model for the minimum substrate binding requirement of NXET is proposed. Springer-Verlag, 1996 Cell wall (plant) nationallicence Enzyme (specificity) nationallicence Hemicellulose nationallicence Tropaeolum nationallicence Xyloglucan nationallicence Xyloglucan endo -transglycosylase nationallicence G : unsubstituted glucose residue nationallicence X : xylose-substituted glucose residue nationallicence L : galactosylxylose-substituted glucose residue nationallicence F : fucosyl-galactosylxylose-substituted glucose residue nationallicence Gal : galactose nationallicence Glc : glucose nationallicence HPAE : high-performance anion-exchange chromatography nationallicence NXET : nasturtium xyloglucan endo-transglycosylase or xyloglucan-specific endo-(1→4)-β-d-glucanase nationallicence Xyl : xylose nationallicence Fanutti Cristina Department of Biological and Molecular Sciences, University of Stirling, FK9 4LA, Stirling, UK aut Gidley Michael Unilever Research Laboratory, Colworth House, MK44 1LQ, Sharnbrook, Beford, UK aut Reid J. Department of Biological and Molecular Sciences, University of Stirling, FK9 4LA, Stirling, UK aut Planta Springer-Verlag 200/2(1996-10-01), 221-228 0032-0935 200:2<221 1996 200 425 https://doi.org/10.1007/BF00208312 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00208312 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Fanutti Cristina Department of Biological and Molecular Sciences, University of Stirling, FK9 4LA, Stirling, UK aut NATIONALLICENCE 700 1- Gidley Michael Unilever Research Laboratory, Colworth House, MK44 1LQ, Sharnbrook, Beford, UK aut NATIONALLICENCE 700 1- Reid J. Department of Biological and Molecular Sciences, University of Stirling, FK9 4LA, Stirling, UK aut NATIONALLICENCE 773 0- Planta Springer-Verlag 200/2(1996-10-01), 221-228 0032-0935 200:2<221 1996 200 425 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer