中文摘要：

S-thanatin是一个含有21个氨基酸的抗菌肽，以融合形式在大肠杆菌体内表达，载体构建时人工设计了一个凝血酶位点。为降低重组抗菌肽S-thanatin的生产成本以利于工业化生产，探索了一个处理速度快且成本较低的分离纯化策略。通过大肠杆菌pET-32a/BL21（DE3）系统高效可溶表达融合蛋白后，首先分析了融合蛋白的表达部位，然后利用融合蛋白热稳定性高的性质通过加热去除不耐热的大分子质量蛋白，同时降低蛋白酶对融合蛋白的影响。离心后溶液通过中空纤维超滤来浓缩融合蛋白，之后进行固定化凝血酶酶切。酶切后的TrxA片段和目的多肽利用其分子质量的差异，使用超滤膜包进行分离，最后使用制备反相高效液相对S-thanatin进行精制，并检测其对大肠杆菌ATCC25922的抗菌活性。结果表明，通过这一简单的纯化工艺，可制备出纯度95％以上的S—thanatin，并具有很好的抗菌活性。

英文摘要：

S-thanatin, a small antimicrobial peptide with 21 amino acid residues ,was expressed as a fusion protein containing thrombin cleavage site in Escherichia coli BL21 （DE3）. To lower the production cost of S-thanatin and to facilitate the industrial production ,a separation and purification strategy with a fast processing speed and lower cost was explored in this study. Firstly, S-thanatin-TrxA fusion protein was solubly expressed by a built pET-32a/BL21 （ DE3 ） expression system and the expression sites were analyzed. Then many unstable proteins were removed through heating based on thermal stability nature of the fusion protein, while inhibiting the protease activity to degrade fusion protein at the same time. After centrifugation, the fusion protein solution was compressed through hollow fiber ultrafiltration. Then TrxA and S-thanatin were separated according to molecular weight difference after immobilized thrombin digestion by using ultrafiltration membrane separation package, and finally refined by semi-preparation RP-HPLC. The resuhs showed that,through this simple process, S-thanatin with the purity of over 95% was prepared and significant antibacterial activity against E. coli ATCC25922 was exhibited.