title: Solubilization of beta-glucan synthases from the membranes of cultured ryegrass endosperm cells.
abstract: beta-Glucan synthases were solubilized by treating membrane preparations from suspension-cultured ryegrass (lolium multiflorum) endosperm cells with detergents. Of the seven detergents tested only digitonin and octyl glucoside dissociated active synthases from the membranes. The digitonin-solubilized enzymes produced 1,4-beta-glucans and 1,3:1,4-beta-glucans, whereas the digitonin-insoluble enzymes produced, in addition, 1,3-beta-glucans. Chromatography of the digitonin-solubilized beta-glucan synthases on DEAE-Sepharose resulted in their partial purification. The octyl glucoside-solubilized enzymes produced more 1,3-beta-glucans than did the membrane-bound preparations. These results suggest that the 1,3-beta-glucan synthase is a separate enzyme and is not involved in 1,3:1,4-beta-glucan synthesis. Digitonin not only dissociated synthases from the membranes, but also stimulated synthase activity. This effect may be related to the inhibition by digitonin of glucosyl transfer from UDP-glucose to form steryl glucosides.
mesh_terms: D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D003902:Detergents / Q000494:pharmacology; D004072:Digitonin / Q000494:pharmacology; D005960:Glucosides / Q000494:pharmacology; D005964:Glucosyltransferases / Q000302:isolation & purification* / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D012434:Secale / Q000201:enzymology; D012639:Seeds / Q000187:drug effects / Q000201:enzymology*; D012995:Solubility
chemical_list: D003902:Detergents; D005960:Glucosides; D008565:Membrane Proteins; C018619:octyl-beta-D-glucoside; D005964:Glucosyltransferases; D004072:Digitonin