Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute.
J Agric Food Chem. 2010 Feb 10;58(3):1970-5. doi: 10.1021/jf9035595.
An acidic endo-beta-1,4-glucanase, denoted CelA4 ( approximately 48 kDa), was purified from thermoacidophilic Alicyclobacillus sp. A4. Two internal peptides of CelA4 showed strong sequence identity to the Alicyclobacillus acidocaldarius cellulase precursor and contained the conserved domain and catalytic region of glycoside hydrolase family 51 beta-1,4-glucanases, and the N-terminal and three other internal peptides had no close glucanase or cellulase relatives, suggesting that the enzyme might be novel. CelA4 had broad substrate specificity, exhibited maximum activity at 65 degrees C and pH 2.6, was stable over pH 1.8-7.6, and showed strong resistance to acidic and neutral proteases, notably pepsin. In comparison to the commercial endo-beta-1,3-1,4-glucanase, CelA4 was more stable, released more reducing sugar from barley beta-glucan, and under simulated gastric conditions, decreased the viscosity of barley-soybean feed to a greater extent. These properties make CelA4 a good candidate as a new commercial glucanase to improve the nutrient bioavailability of pig feed.
一种酸性内切-β-1,4-葡聚糖酶，命名为 CelA4（约 48 kDa），从嗜热嗜酸脂环酸芽孢杆菌 A4 中纯化得到。CelA4 的两个内部肽段与 Alicyclobacillus acidocaldarius 纤维素酶前体具有很强的序列同一性，并且含有糖苷水解酶家族 51β-1,4-葡聚糖酶的保守结构域和催化区域，而 N 端和另外三个内部肽段与其他纤维素酶或内切葡聚糖酶没有密切的亲缘关系，表明该酶可能是新型的。CelA4 具有广泛的底物特异性，在 65°C 和 pH 2.6 时表现出最大活性，在 pH 1.8-7.6 之间稳定，并且对酸性和中性蛋白酶具有很强的抗性，特别是胃蛋白酶。与商业内切-β-1,3-1,4-葡聚糖酶相比，CelA4 更稳定，从大麦β-葡聚糖中释放出更多的还原糖，并且在模拟胃条件下，使大麦-大豆饲料的粘度降低到更大的程度。这些特性使 CelA4 成为一种有前途的新型商业葡聚糖酶，可提高猪饲料的营养生物利用率。
