Characterization of the biochemical properties of recombinant Xyn10C from a marine bacterium, Saccharophagus degradans 2-40

Abstract

Endo-1,4-beta-xylanases are mostly classified into glycoside hydrolase (GH) family 10 or 11. In this study, we examined the catalytic functions of a recombinant endo-1,4-beta-xylanase belonging to GH10 (Xyn10C) from a marine bacterium, Saccharophagus degradans 2-40. Optimal activity of this enzyme was evident at 30 A degrees C and pH 7.0, but activity remained even at low temperatures, indicating its adaptation to cold. With respect to other xylanases known to be active in cold temperatures, Xyn10C is unique in that it showed maximal activity in the presence of 2 M of NaCl. The action patterns of recombinant Xyn10C on xylans from hardwood and softwood differed in part, but the enzyme hydrolyzed polysaccharidic substrates primarily to xylobiose and xylotriose through xylo-oligosaccharides, releasing a small amount of xylose. The K (m) and V (max) values on birchwood xylan were 10.4 mg mL(-1) and 253 A mu mol mg(-1) min(-1), respectively. The efficient catalytic function of Xyn10C on short-length xylo-oligosaccharide chains was similar to the typical function of other known GH10 xylanases.