PMID:9020869

Citation	Herrmann, MC, Vrsanska, M, Jurickova, M, Hirsch, J, Biely, P and Kubicek, CP (1997) The beta-D-xylosidase of Trichoderma reesei is a multifunctional beta-D-xylan xylohydrolase. Biochem. J. 321 ( Pt 2):375-81
Abstract	An extracellular multifunctional beta-D-xylan xylohydrolase, previously described as beta-xylosidase, was purified from Trichoderma reesei RUT C-30 to physical homogeneity. The active enzyme was a 100 (+/-5) kDa glycosylated monomer that exhibited a pl of 4.7. Its activity was optimal at pH 4 and it was stable between pH 3 and 6. Its temperature-stability was moderate (70 degrees zero of activity remaining after 60 min at 50 degrees C) and optimal activity was observed at 60 degrees C. It is capable of hydrolysing beta-1.4-xylo-oligosaccharides [degree of polymerization (DP) 2-7], the apparent Vmax increasing with increasing chain length. The enzyme also attacked debranched beech-wood (Lenzing) xylan and 4-O-methylglucuronoxylan, forming xylose as the only end product. The K(m) for xylan was 0.7 g/l. For this reason we consider the enzyme to be a beta-D-xylan xylohydrolase. The enzyme also exhibits alpha-L-arabinofuranosidase activity on 4-nitrophenyl alpha-L-arabinofuranoside, and evidence is presented that this is not caused by an impurity in the enzyme preparation. The beta-D-xylan xylohydrolase exhibits glycosyltransferase activity with xylo-oligosaccharides and at high concentrations of 4-nitrophenyl beta-D-xylopyranoside (4-Nph-beta-Xyl). The enzyme hydrolyses beta-1, 4-linkages preferentially to beta-1,3-linkages, and beta-1,2-linked xylo-oligosaccharides are not hydrolysed at all. The enzyme liberates terminal beta-1,4-xylopyranose residues linked to a 2-O-substituted xylopyranose residue, but not that linked to a 3-O-substituted xylopyranose residue. The enzyme does not attack methyl, methyl 1-thio-benzyl or butyl l-thio-beta-D-xylopyranosides and 4-naphthyl, 2-naphthyl and phenyl beta-D-xylopyranosides.
Links	PubMed PMC1218079
Keywords	Amino Acid Sequence; Carbohydrate Sequence; Chemistry, Physical; Fungal Proteins/antagonists & inhibitors; Fungal Proteins/chemistry; Fungal Proteins/isolation & purification; Glycosylation; Molecular Sequence Data; Multienzyme Complexes/antagonists & inhibitors; Multienzyme Complexes/chemistry; Multienzyme Complexes/isolation & purification; Physicochemical Phenomena; Substrate Specificity; Trees/enzymology; Trichoderma/enzymology; Xylose/pharmacology; Xylosidases/antagonists & inhibitors; Xylosidases/chemistry; Xylosidases/isolation & purification
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
HYPJE:Q92458		GO:0005975: carbohydrate metabolic process	ECO:0000314:		P		fig 2.: change in reactants/product levels during hydrolysis fig 1.: shows purity of beta-xylosidase in comparison to marker proteins	complete CACAO 4530

References

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