| Résumé | Biodegradation of hemicelluloses requires enzyme activities that remove nonxylose substituents from the xylan backbone in addition to endoxylanases and β-xylosidases. Activities removing o-acetyl, arabinose, cinnamic acid-based esters, and uronic acid substituents occurred inStreptomyces olivochromogenes, Aspergillus niger, andSchizophyllum commune. 4-O-Methylglucuronidase was coinduced with other substituent-hydrolyzing enzymes when appropriate lignocellulosic materials were provided. Fractionation of crude enzymes indicated that the 4-o-methylglucuronidases were polydisperse. The 4-o-methylglucuronidases fromS. commune andA. niger acted on high molecular weight heteroxylans, but those from S.olivochromogenes functioned only with small, endo-β-(1,4)-xylanse-solubilized fragments |
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