title: Induction of cellulose- and xylan-degrading enzyme systems in Aspergillus terreus by homo- and heterodisaccharides composed of glucose and xylose.
abstract: Synthetic heterodisaccharides composed of glucose and xylose were tested as inducers of cellulose- and xylan-degrading enzymes in Aspergillus terreus, and the inducing abilities were compared with those of sophorose and xylobiose or their positional isomers. Measurement of secreted and cell-associated enzyme activities revealed that the heterodisaccharides induced the synthesis of the cellulolytic and xylanolytic enzymes, 2-O-beta-D-glucopyranosyl D-xylose (Glcbeta 1-2Xyl) being the most powerful inducer. Sophorose and 2-O-beta-D-xylopyranosyl D-Xylose (Xylbeta 1-2Xyl), or their positional isomers, selectively induced the synthesis of cellulases and beta-xylanases, respectively. An analysis of the extracellular enzymes (which were separated by isoelectric focusing followed by detection using chromogenic and fluorogenic substrates) showed that Glcbeta 1-2Xyl initiated the synthesis of specific endo-1,4-beta-glucanases and specific endo-1,4-beta-xylanases identical to those produced separately in response to sophorose or Xylbeta 1-2Xyl. Glcbeta 1-2Xyl also induced specific endo-1,4-beta-glucanases that hydrolysed 4-methylumbelliferyl beta-lactoside at the agluconic bond. The results strengthen the concept of separate regulatory control of the synthesis of cullulases and beta-xylanases. The results also suggest that mixed disaccharides, composed of glucose and xylose moieties, which may occur in nature, could play an important role in regulating the synthesis of wood-degrading enzymes.
authors.affiliation: Institute of Chemistry, Slovak Academy of Sciences, Bratislava, Czechoslovakia.
authors.forename: M
authors.initials: M
authors.lastname: Hrmová
authors.forename: E
authors.initials: E
authors.lastname: Petráková
authors.forename: P
authors.initials: P
authors.lastname: Biely
mesh_terms: D001230:Aspergillus / Q000201:enzymology*; D002240:Carbohydrate Sequence; D002480:Cellulase / Q000378:metabolism; D002482:Cellulose / Q000378:metabolism*; D004187:Disaccharides / Q000378:metabolism*; D004789:Enzyme Activation; D005947:Glucose / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000378:metabolism*; D008969:Molecular Sequence Data; D043325:Xylan Endo-1,3-beta-Xylosidase; D014990:Xylans / Q000378:metabolism*; D014994:Xylose / Q000378:metabolism*
chemical_list: D004187:Disaccharides; D014990:Xylans; D002482:Cellulose; D014994:Xylose; D006026:Glycoside Hydrolases; D043325:Xylan Endo-1,3-beta-Xylosidase; D002480:Cellulase; D005947:Glucose