A procedure has been devised to extract and identify structural components of the xyloglucan ofZea maysL. (hybrid B73×Mo 17) shoot cell-walls. A water-insoluble fraction ofZeashoot cell-walls, after pretreatment with purifiedBacillus subtilis(1→3),(1→4)-β-D-glucan 4-glucanohydrolase, purifiedB. subtilisendo-(l→4)-β-xylanase and an enzyme preparation fromB. subtilisenriched in glucuronoxylanase (Kato and Nevins 1984a, Nishitani and Nevins 1991), was subsequently treated with 7 M urea. The carbohydrates (0.8of the water-insoluble fraction ofZeashoot cell-walls) liberated by the urea treatment, were comprised of xyloglucan polymers with molecular weights which varied from 1.0×104to 4.0 7times; 104Da. Other wall fragments associated with the isolated polymer suggest covalent bonding of xyloglucan to other polysaccharides.Structural analyses of the xyloglucan polymers reveal a cellulose-like backbone with about 35of the C-6 positions substituted with xylose and other sugars. About 80of xyloglucan present in the enzyme-pretreated water-insoluble fraction ofZeashoot cell-walls was liberated by the urea treatment. The procedure avoids the use of alkali in the solubilization of x
展开▼
