Abstract A neutral xylanase (XynII) from Volvariella volvacea was identified and characterized. Unlike other modular xylanases, it consists of only a single GH10 cata- lytic domain with a unique C-terminal sequence (W-R-W-F) and a phenylalanine and proline-rich motif (T-P-F-P-P-F) at N-terminus, indicating that it is a novel GH10 xylanase. XynII exhibited optimal activity at pH 7 and 60 C and stability over a broad range of pH 4.0–10.0. XynII dis- played extreme highly SDS resistance retaining 101.98,
92.99, and 69.84 % activity at the presence of 300 mM SDS on birchwood, soluble oat spelt, and beechwood xylan, respectively. It remained largely intact after 24 h of incubation with proteinase K at a protease to protein ratio of 1:50 at 37 C. The kinetic constants Km value towards
beechwood xylan was 0.548 mg ml-1, and the kcat/Km
ratio, reflecting the catalytic efficiency of the enzyme, was
126.42 ml mg-1 s-1 at 60 C. XynII was a true endo-act- ing xylanase lacking cellulase activity. It has weak activity towards xylotriose but efficiently hydrolyzed xylans and
xylooligosaccharides larger than xylotriose mainly to xylobiose. Synergistic action with acetyl xylan esterase (AXEI) from V. volvacea was observed for de-starched wheat bran. The highest degree of synergy (DS 1.42) was obtained in sequential reactions with AXEI digestion pre- ceding XynII. The high SDS resistance and intrinsic sta- bility suggested XynII may have potential applications in various industrial processes especially for the detergent and textile industries and animal feed industries.
Abstract A neutral xylanase (XynII) from Volvariella volvacea was identified and characterized. Unlike other modular xylanases, it consists of only a single GH10 cata- lytic domain with a unique C-terminal sequence (W-R-W-F) and a phenylalanine and proline-rich motif (T-P-F-P-P-F) at N-terminus, indicating that it is a novel GH10 xylanase. XynII exhibited optimal activity at pH 7 and 60 C and stability over a broad range of pH 4.0–10.0. XynII dis- played extreme highly SDS resistance retaining 101.98,92.99, and 69.84 % activity at the presence of 300 mM SDS on birchwood, soluble oat spelt, and beechwood xylan, respectively. It remained largely intact after 24 h of incubation with proteinase K at a protease to protein ratio of 1:50 at 37 C. The kinetic constants Km value towardsbeechwood xylan was 0.548 mg ml-1, and the kcat/Kmratio, reflecting the catalytic efficiency of the enzyme, was126.42 ml mg-1 s-1 at 60 C. XynII was a true endo-act- ing xylanase lacking cellulase activity. It has weak activity towards xylotriose but efficiently hydrolyzed xylans andxylooligosaccharides larger than xylotriose mainly to xylobiose. Synergistic action with acetyl xylan esterase (AXEI) from V. volvacea was observed for de-starched wheat bran. The highest degree of synergy (DS 1.42) was obtained in sequential reactions with AXEI digestion pre- ceding XynII. The high SDS resistance and intrinsic sta- bility suggested XynII may have potential applications in various industrial processes especially for the detergent and textile industries and animal feed industries.
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