Enzymic Dissociation of Zea Shoot Cell Wall Polysaccharides : II. Dissociation of (1 --> 3),(1 --> 4)-beta-d-Glucan by Purified (1 --> 3),(1 --> 4)-beta-d-Glucan 4-Glucanohydrolase from Bacillus subtilis.
The water-insoluble cell wall fraction obtained after successive treatments of an insoluble fraction of a buffer-homogenate of Zea shoots with 3 molar LiCl, hot water and alpha-amylase, was subjected to dissociation by enzymes. Treatment of the water-insoluble fraction with the purified Bacillus subtilis (1 --> 3),(1 --> 4)-beta-d-glucan 4-glucanohydrolase dissociated cell wall fragments (5.1% of the water-insoluble fraction) which were characterized in detail. Structural analyses of the fragment oligosaccharides revealed blocks of more than three contiguous (1 --> 4)-linkages and regions consisting of two or more contiguous (1 --> 3)-linkages. On the basis of these results, we propose that the Zea shoot beta-d-glucan may be represented as a folded structure. Furthermore, the presence of contiguous (1 --> 3)-linkages in the beta-d-glucan offers potential sites for enzyme attack and may account for the generation of specific products released by the endogenous endo-beta-d-glucanase in autolysis and/or polymer modification process in Zea shoot cell walls.
Kato
Y
Y
Department of Botany, Iowa State University, Ames, Iowa 50011.
Nevins
D J
DJ