A novel member of family 30 glycoside hydrolase subfamily 8 glucuronoxylan endo-β-1,4-xylanase (CtXynGH30) from Clostridium thermocellum orchestrates catalysis on arabinose decorated xylans

•CtXynGH30 represent a novel member of glycoside hydrolase family 30 subfamily 8.•Identified as glucuronoxylan endo-β-1,4-xylanase.•Capable of hydrolysing both glucuronic and arabinose moiety decorated xylans.•Produced acidic xylo-oligosaccharides predominantly having methyl glucuronic acid moiety penultimate to the reducing end of xylan.

A thermophilic enzyme, CtXynGH30 from Clostridium thermocellum was identified as glucuronoxylan endo-β-1,4-xylanase displayed activity extending to arabinose decorated xylans unlike other glucuronoxylan endo-β-1,4-xylanase from family 30 sub-family 8 of glycoside hydrolase. Modular CtXynGH30 comprises N-terminal catalytic module CtXyn30A and C-terminal carbohydrate binding module of family 6, (CtCBM6). The purified CtXynGH30 displayed a molecular mass of approximately, 60 kDa. CtXynGH30 showed an optimum pH 6.0 and optimum temperature 70 °C. CtXynGH30 displayed maximum activity against glucuronic acid substituted beechwood xylan followed by birchwood- and 4-O-methyl glucurono-xylan. CtXynGH30 also displayed activity against arabinoxylans that were also confirmed by TLC analysis. The ability of CtXynGH30 to hydrolyse both glucuronic and arabinose decorated xylans distinguishes it from other enzymes of this subfamily. The 1H NMR analysis of hydrolysed products of beechwood xylan confirmed the presence of acidic xylo-oligosaccharides having methyl glucuronic acid moiety penultimate to the reducing end of xylan. CtXynGH30 produced a range of acidic xylo-oligosaccharides and arabinoxylo-oligosaccharides which have potential food and health applications.

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