Biochemical and catalytic properties of an endoxylanase purified from the culture filtrate of Thermomyces lanuginosus ATCC 46882

Document identifier: oai:DiVA.org:ltu-7584
Access full text here:10.1016/S0008-6215(97)10076-3
Publication year: 1998
Abstract:

An endoxylanase (1,4-beta-D-xylan xylanohydrolase, EC 3.2.1.8) from the culture filtrates of T. lanuginosus ATCC 46882 was purified to homogeneity by DEAE-Sepharose and Bio-Gel P-30 column chromatographies. The purified endoxylanase had a specific activity of 888.8 mumol min-1 mg-1 protein and accounted for approximately 30% of the total protein secreted by this fungus. The molecular mass of native (non-denatured) and denatured endoxylanase were 26.3 and 25.7 kD as, respectively. Endoxylanase had a pI of 3.7 and was optimally active between pH 6.0-6.5 and at 75 degrees C. The enzyme showed > 50% of its original activity between pH 5.5-9.0 and at 85 degrees C. The pH and temperature stability studies revealed that this endoxylanase was almost completely stable between pH 5.0-9.0 and up to 60 degrees C for 5 h and at pH 10.0 up to 55 degrees C for 5 h. Thin-layer chromatography (TLC) analysis showed that endoxylanase released mainly xylose (Xyl) and xylobiose (Xyl2) from beechwood 4-O-methyl-D-glucuronoxylan, O-acetyl-4-O-methyl-D-glucuronoxylan and rhodymenan (a beta-(1-->3)-beta(1-->4)-xylan). Also, the enzyme released an acidic xylo-oligosaccharide from 4-O-methyl-D-glucuronoxylan, and an isomeric xylotetraose and an isomeric xylopentaose from rhodymenan. The enzyme hydrolysed [1-3H]-xylo-oligosaccharides in an endofashion, but the hydrolysis of [1-3H]-xylotriose appeared to proceed via transglycosylation. since the xylobiose was the predominant product. Endoxylanase was not active on pNPX and pNPC at 40 and 100 mM for up to 6 h, but showed some activity toward pNPX at 100 mM after 20-24 h. The results suggested that the endoxylanase from T. lanuginosus belongs to family 11.

Authors

Neil A. Bennett

Institute of Food Research
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James Ryan

Institute of Food Research
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Peter Biely

Slovak Academy of Sciences, Bratislava
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Maria Vrsanska

Slovak Academy of Sciences, Bratislava
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Lubomir Kremnicky

Slovak Academy of Sciences, Bratislava
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Basil J. Macris

National Technical University of Athens
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Dimitris Kekos

National Technical University of Athens
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Paul Christakopoulos

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Petros Katapodis

National Technical University of Athens
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Marc Claeyssens

University of Ghent
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Wim Nerinckx

University of Ghent
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Patricia Ntauma

University of Ghent
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Mahalingeshwara K. Bhat

Institute of Food Research
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