Biochemical and catalytic properties of an endoxylanase purified from the culture filtrate of Thermomyces lanuginosus ATCC 46882
Biochemical and catalytic properties of an endoxylanase purified from the culture filtrate of Thermomyces lanuginosus ATCC 46882
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DOI：
10.1016/s0008-6215(97)10076-3
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发表时间：
1998-01-01
影响因子：
3.1
通讯作者：
Bhat, MK
中科院分区：
文献类型：
--
作者：
Bennett, NA;Ryan, J;Bhat, MK
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 mu mol 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 (Xyl(2)) 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-H-3]-xylo-oligosaccharides in an endofashion, but the hydrolysis of [1-H-3]-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 towards pNPX at 100 mM after 20-24 h. The results suggested that the endoxylanase from T. lanuginosus belongs to family 11. (C) 1998 Elsevier Science Ltd. All rights reserved.
