中文摘要：

脂肪酶广泛应用于食品加工、生物柴油制备等领域。为了有效提高微生物脂肪酶的可利用度,将来源于南极嗜冷杆菌属（antarctic psychrotrophic bacterium,Psychrobacter sp.7195）的嗜冷脂肪酶（Lip7195）在大肠杆菌系统中进行高效可溶性表达优化,并进行酶学性能表征。首先对Lip7195基因进行大肠杆菌偏好密码子优化,并通过添加多聚阳离子氨基酸标签等手段,优化重组Lip7195的可溶性表达。结果显示,添加多聚阳离子氨基酸标签的方法有效增加了目的蛋白的可溶性。对纯化后的重组酶进行酶学定性,结果显示,在40℃、p H 9.0时,重组Lip7195酶活性最高,比酶活最高达10.9 U/mg;在30-40℃、p H 8.0-10.0范围,重组Lip7195具有较好的稳定性;Co（2＋）对酶活力有激活作用。研究结果表明,在保持嗜冷脂肪酶特有的酶学性质基础上,添加多聚阳离子氨基酸标签有效改善了其在原核表达中易形成包涵体的问题。

英文摘要：

Lipase is any enzyme that catalyzes the hydrolysis of lipids, and is the subclass of the esterases. Given its ex- cellent functions, lipase plays an indispensable role in many industrial areas such as food processing and biodiesel prepa- ration. In this paper, in order to effectively improve the ulilization of lipase from microbes, a psychrophilic lipase gene from antarctic psyehrotrophic bacterium, Psychrobacter sp. 7195 （Lip7195） was cloned into the commercial plasmid pTrc99a by the methods of polymerase chain reaction （PCR） and DNA restriction enzyme digestion as well as ligation. The recombinant lipase was chemically induced in the presence of isopropyl β-D-Thiogalactoside （IPTG） and heterologously expressed in Escherichia coll. The proportion of the soluble recombinant lipase was significantly enhanced by a series of modifications at various levels including optimizing codon usage, incorporating polycationic amiuo acid tags. The engineered recombinant lipase showed the maxinlum activities at 40 ℃ and pH 9.0. The specific activity was determined as 10.9 U/mg. The thermal stability assay exhibited that Lip7195 was fairly thermally stable at the temperatures ranging from 30 to 40 ℃ , and at the pH values from 8.0 to 10.0. The recombinant Lip7195 was chemically activated in the presence of metal ion Co2＋ under the assay conditions. The results indicate that these modifications can effectively decrease the formation of inclusion body in the protein biosynthesis process in E. coll. Apart from the decrease in the inclusion body of the desired protein, the biochemical property and catalytic ability of recombinant Lip7195 can be intactly main- rained after the relevant modifications.