College of Food Science and Nutritional Engineering, The Research and Innovation Center of Food Nutrition and Human Health (Beijing), China Agricultural University, Beijing 100083, China.
Bioresource Utilization Laboratory, College of Engineering, China Agricultural University, Beijing 100083, China.
Food Chem. 2016 Feb 1;192:1041-8. doi: 10.1016/j.foodchem.2015.07.092. Epub 2015 Jul 23.
A novel chitinase gene (PbChi70) from a marine bacterium Paenicibacillus barengoltzii was cloned and functionally expressed in Escherichia coli. The recombinant enzyme (PbChi70) was purified to homogeneity with a recovery yield of 51.9%. The molecular mass of purified enzyme was estimated to be 70.0 kDa by SDS-PAGE. PbChi70 displayed maximal activity at pH 5.5 and 55 °C, respectively. It exhibited strict substrate specificity for colloidal chitin, glycol chitin, powdery chitin, and N-acetyl chitooligosaccharides with degrees of polymerization above three. The enzyme exhibited an endo-type cleavage pattern and hydrolyzed colloidal chitin to yield mainly (GlcNAc)2. Furthermore, colloidal chitin was hydrolyzed by PbChi70 to produce 21.6 mg mL(-1) (GlcNAc)2 with the highest conversion yield of 89.5% (w/w). (GlcNAc)2 was further separated by an active charcoal column with a purity of 99% and a final yield of 61%. The unique enzymatic properties of the chitinase may make it a good candidate for (GlcNAc)2 production.
一种新型的几丁质酶基因（PbChi70）来自海洋细菌 Paenicibacillus barengoltzii 在大肠杆菌中被克隆和功能表达。重组酶（PbChi70）经纯化后达到均一性，回收率为 51.9%。SDS-PAGE 估计纯化酶的分子量为 70.0 kDa。PbChi70 在 pH 5.5 和 55°C 时分别显示出最大活性。它对胶体几丁质、乙二醇几丁质、粉状几丁质和聚合度大于三的 N-乙酰壳寡糖具有严格的底物特异性。该酶表现出内切型切割模式，将胶体几丁质水解主要生成（GlcNAc）2。此外，胶体几丁质被 PbChi70 水解生成 21.6mg mL(-1)（GlcNAc）2，转化率最高为 89.5%（w/w）。（GlcNAc）2 进一步通过活性炭柱分离，纯度为 99%，最终收率为 61%。几丁质酶的独特酶学性质可能使其成为（GlcNAc）2 生产的良好候选者。
