人子宫颈黏液抗菌多肽的分离和鉴定

目的　从人的子宫颈黏液分离和鉴定新抗菌多肽,探讨子宫颈黏液抗菌机制。方法　用5%乙酸提取人子宫颈黏液可溶物,应用电泳凝胶抗菌蛋白分析法分析其抗菌蛋白,制备酸性尿素聚丙烯酰胺凝胶电泳及反相高效液相色谱分离纯化抗菌多肽。凝胶琼脂糖弥散法抗菌检测抗菌活性。纯化的抗菌多肽进行氮端氨基酸序列测定,根据其序列设计简并引物,利用简并聚合酶链反应(PCR)技术扩增其全长cDNA。通过BLAST硷基比对程序分析比较与已知蛋白的同源性。进一步应用常规基因重组技术构建其原核表达质和制备重组多肽。采用最小抑菌浓度和最小杀菌浓度检测重组多肽的抗菌效能。结果　从子宫颈黏液中分离纯化到一个具抗菌活性的多肽,通过蛋白测序、简并PCR及BLAST等方法鉴定该蛋白为HMGN2高游动性蛋白。制备获得重组HMGN2多肽,重组HMGN2抗大肠杆菌和铜绿假单胞菌的最小抑菌浓度分别为10 .42μg/ml±3. 13μg/ml和27. 78μg/ml±8 .33μg/ml,与人中性粒细胞防御素相当;最小杀菌浓度分别为20 .83μg/ml±6 .25μg/ml和55 .56μg/ml±16 .67μg/ml。结论　除已知的抗菌肽外,HMGN2亦可能是宫颈黏液含有的抗感染效应分子之一。

Study of antmicrobial mechanisms of human cervical mucus: isolation and characterization of antibacterial polypeptides

OBJECTIVE: To isolate and purify antibacterial polypeptides from human cervical mucus. METHODS: Human cervical mucus was collected from human healthy subjects and acid-soluble extract was obtained by solving the mucus with 5% acetic acid in the presence of protease inhibitors. The antibacterial components were identified by Agar radial diffusion assay and gel overlay technique. For further purification, Preparative acid-urea gel electrophoresis and Reverse Phase HPLC were performed. The N-terminal sequencing and degenerate PCR-directered cDNA cloning were performed. The E. coli-based recombinant product was prepared and its antibacterial property was determined by minimal inhibitory concentration and minimal bactericidal concentration. RESULTS: A purified antibacterial polypeptide was obtained. Agar radial diffusion assay showed that the purified polypeptide had antibacterial activities against E. coli ML-35P and Pseudomanas aeruginosa ATCC 27853. The N-terminal amino acid sequence and its full length of cDNA were identical to High Mobility Group Chromosal protein N2 (HMGN2). The purified recombinant HMGN2 was obtained. Its MIC against E. coli ML-35p and P. aeruginosa ATCC27853 were 10.42 microg/ml +/- 3.13 microg/ml and 27.78 microg/ml +/- 8.33 microg/ml respectively, which were equal to human neutrophil defensins HNP, and the MBC were 20.83 microg/ml +/- 6.25 microg/ml and 55.56 microg/ml +/- 16.67 microg/ml respectively. CONCLUSION: HMGN2 may be another antibacterial effecter in the defense mechanisms of human cervical mucus.