Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China.
Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China; Key Laboratory of Microbial Resource Collection and Preservation, Ministry of Agriculture and Rural Affairs, Beijing, 100081, China.
Protein Expr Purif. 2021 Mar;179:105798. doi: 10.1016/j.pep.2020.105798. Epub 2020 Nov 21.
A pectinase-producing bacterial isolate, identified as Paenibacillus xylanexedens SZ 29, was screened by using the soil dilution plate with citrus pectin and congo red. A pectin methylesterase gene (Pxpme) was cloned and expressed in Escherichia coli. The gene coded for a protein with 334 amino acids and a calculated molecular mass of 36.76 kDa. PxPME showed the highest identity of 32.4% with the characterized carbohydrate esterase family 8 pectin methylesterase from Daucus carota. The recombined PxPME showed a specific activity with 39.38 U/mg against citrus pectin with >65% methylesterification. The optimal pH and temperature for PxPME activity were 5.0 and 45 °C. Its K and V value were determined to be 1.43 mg/mL and 71.5 μmol/mg·min, respectively. Moreover, PxPME could increase the firmness of pineapple cubes by 114% when combined with CaCl. The acidic and mesophilic properties make PxPME a potential candidate for application in the fruit processing.
一株产果胶酶的细菌分离株，被鉴定为嗜碱性芽孢杆菌 SZ 29，通过使用含有柑橘果胶和刚果红的土壤稀释平板进行筛选。克隆并在大肠杆菌中表达了一种果胶甲酯酶基因（Pxpme）。该基因编码一个由 334 个氨基酸组成的蛋白质，分子量为 36.76 kDa。PxPME 与已鉴定的胡萝卜碳水化合物酯酶家族 8 果胶甲酯酶的同源性最高，为 32.4%。重组 PxPME 对>65%甲酯化的柑橘果胶的比活为 39.38 U/mg。PxPME 活性的最适 pH 和温度分别为 5.0 和 45°C。其 K 和 V 值分别为 1.43 mg/mL 和 71.5 μmol/mg·min。此外，PxPME 与 CaCl 结合可使菠萝块的硬度提高 114%。PxPME 的酸性和嗜温特性使其成为水果加工应用的潜在候选者。
