粘质沙雷氏菌低温脂肪酶的基因克隆与酶学性质分析
Gene cloning and characterization of low-temperature lipase from Serratia sp.

克隆一个源于北极冻土沙雷氏菌的脂肪酶基因lip18，实现其在大肠杆菌中的表达，并进行酶学性质研究. 克隆脂肪酶基因lip18，并构建pET-28a(+)-lip18重组表达载体，导入大肠杆菌BL21(DE3)中，诱导优化重组蛋白表达，并研究其酶学性质. 克隆得到脂肪酶基因lip18，全长为1842bp，编码614个氨基酸. 重组菌的诱导温度对蛋白表达影响很大，在最适诱导温度为20℃时脂肪酶大量表达，重组脂肪酶的相对分子质量约为65ku. 酶学性质研究表明：重组酶高效水解C10~C16的中、长链脂肪酸，最适作用温度30℃，最适作用pH值 7.0，并且在0℃条件下有一定的催化活性，热稳定性差，是低温中性脂肪酶；同时，对有机溶剂有较好的耐受性.
The gene lip18 encoding lipase from Serratia sp. screened from Arctic tundra was cloned and expressed in Escherichia coli，the enzymatic properties were characterized. The lip18 gene was amplified and integrated into the genome of E.coli BL21(DE3) via the pET-28a(+) vector. The induction of the recombinant protein was optimized，then the enzymatic properties of the recombinant enzyme was studied. A new gene lip18 consists of 1842bp，encoding 614 amino acids，was cloned. After induced by 20℃，recombinant lipase were magnanimous expressed with weight of 65ku. Recombinant protein has high selectivity in C10~C16 medium and long chain fatty acid. The optimum pH and temperature for the recombinant protein was at 7.0 and 30℃，still remained activity at 0℃，was thermal instability and low-temperature lipase. Moreover，the recombinant enzyme have better tolerance of the organic solvent