A novel carbohydrate binding module (CBM) was identified in a β-1,3-xylanase from Flammeovirga pacifica, which showed only 25.0% sequence identity with the reported CBMs with the coverage of 36.4%. To verify its function, a truncated β-1,3-xylanase (Xy13088-T) and a carbohydrate binding module (CBM3088) were expressed and purified. The thermostability and catalytic efficiency of the Xy13088-T declined significantly when compared with the full-length one, with the decreasing of the half-life and catalytic efficiency (Kcat/Km) by 90%. Interestingly, the CBM3088 showed the binding ability to β-1,3-xylan only when Ca2+ existed, which was different from the reported CBMs of β-1,3-xylanases. The maximum amount of CBM3088 binding to β-1,3-xylan was 9.65 μmol/g of β-1,3-xylan. The residues probably involved in the binding to the β-1,3-xylan and Ca2+ were addressed by bioinformatics analysis.

中文翻译：

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来自太平洋金枪鱼的 β-1,3-木聚糖酶的 Ca2+ 依赖性碳水化合物结合模块的首次表征

在来自 Flammeovirga pacifica 的 β-1,3-木聚糖酶中鉴定出一种新的碳水化合物结合模块 (CBM)，其与报道的 CBM 仅显示 25.0% 的序列同一性，覆盖率为 36.4%。为了验证其功能，表达并纯化了截短的 β-1,3-木聚糖酶 (Xy13088-T) 和碳水化合物结合模块 (CBM3088)。与全长相比，Xy13088-T 的热稳定性和催化效率显着下降，半衰期和催化效率（Kcat/Km）降低了 90%。有趣的是，CBM3088 仅在 Ca2+ 存在时才显示出与 β-1,3-木聚糖的结合能力，这与报道的 β-1,3-木聚糖酶的 CBM 不同。CBM3088 与 β-1,3-木聚糖结合的最大量为 9.65 μmol/g β-1,3-木聚糖。可能参与与 β-1 结合的残基，