Action of different types of endoxylanases on eucalyptus xylan in situ.

摘要: Most studies of the mode action industrially important endoxylanases have been done on alkali extracted-plant xylan. In just few cases, native form polysaccharide, acetylated xylan, was used as a substrate. this work xylanases belonging to three glycoside hydrolase families, GH10, GH11, and GH30 investigated acetylglucuronoxylan directly in hardwood cell walls. Powdered eucalyptus wood xylanase Enzyme-generated fragments were characterized by TLC, MALDI ToF MS, NMR spectroscopy. All generated from powder xylooligosaccharides. Those released GH10 enzyme shortest, those largest diversity. For 4-O-methyl-D-glucuronic acid (MeGlcA) side residues function substrate specificity determinants regardless acetylation neighboring hydroxyl group. Much simpler xylooligosaccharide patterns observed when applied combination with carbohydrate esterase family 6 acetylxylan esterase. presence esterase, all aldouronic acids remained 3-O-acetylated xylopyranosyl (Xylp) residue substituted MeGlcA. The 3-O-acetyl group, contrast acetyl groups otherwise unsubstituted Xylp residues, does not affect endoxylanases, but contributes recalcitrance acidic xylan fragments. results confirm importance esterases microbial degradation glucuronoxylan. They also point still unresolved question efficient enzymatic removal group MeGlcA-substituted negatively affecting saccharification yields.