抗菌肽Pc-CATH1结构与功能关系研究及人防御素DEFB18、DEFB20的原核表达
文献类型：学位论文
| 作者 | 董丽 |
| 学位类别 | 硕士 |
| 答辩日期 | 2012-05 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 赖仞 |
| 关键词 | Pc-CATH1 抗菌肽 结构功能关系防御素原核表达 |
| 其他题名 | STRUCTURE-FUNCTION RELATIONSHIP OF ANTIMICROBIAL PEPTIDE PC-CATH1 AND EXPRESSION OF HUMAN DEFENSIN DEFB18, DEFB20 IN E.COLI |
| 学位专业 | 生物化学与分子生物化学 |
| 中文摘要 | 抗菌肽是一类广泛分布于生物体内的小分子多肽，是天然免疫系统的重要组成部分。这些抗菌肽对细菌、真菌、病毒以及肿瘤细胞表现出良好的抑制作用，是新型抗生素开发的良好候选资源。 Pc-CATH1是从雉鸡（Phasianus colchicus）cDNA文库中克隆得到的一条Cathelicidin序列。体外实验表明这条多肽具有广谱抗菌活性，对革兰氏阳性菌、革兰氏阴性菌、真菌以及一些临床分离的耐药菌株都有很好的抑制作用。我们对Pc-CATH1的序列研究时发现该序列具有两个显著的特征：序列的C端和N端电荷分布均匀以及大多数的疏水性氨基酸分布在序列中间。因此我们选择这条抗菌肽作为模板，分别从C端和N端逐个减少氨基酸得到29条Pc-CATH1同系物。我们对30条多肽的抗菌及溶血活性与它们的二级结构、疏水性、两亲性、带电荷数之间的关系进行了初步分析。以上研究结果为改造线性结构的抗菌肽提供一些基础的理论依据。此外，我们改造的多肽LR4及RL5可以作为抗菌肽开发利用的良好候选资源。 DEFB18和DEFB20是通过生物信息学手段从人基因组中发现的两条β防御素抗菌肽。然而目前对于这两条多肽的功能了解的还很少，因此我们利用PET载体系统构建了DEFB18和DEFB20的原核表达载体，然后通过高压液相色谱纯化得到了这两条多肽，并对它们的一些可能存在的生物学功能进行了初步研究。结果显示表达的DEFB18和DEFB20具有清除ABTS自由基的活性，但它们对本实验所用的大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌和白色念珠菌没有抑制作用。 |
| 英文摘要 | Antimicrobial peptides are an important component of the natural defense against invading pathogens. They are distributed in most living organisms and have been demonstrated to kill bacteria, fungi, virus and even transformed or cancerous cells. They are potent candidates for new antibiotics. Cathelicidin Pc-CATH1 is a cathelicidin-derived myeloid antimicrobial peptide identified from Phasianus colchicus with strong antimicrobial activity against most of bacteria and fungi tested, including the clinically isolated (IS) drug-resistant strains. Considering the uniform distribution of net positive charge in both C- and N-terminus sequence of cathelicidin Pc-CATH1 and most of hydrophobic amino acid residues (aa) positioned in middle of the sequence, the antimicrobial peptide was used to investigate the structure-function relationship by truncating gradually N- or C-terminus amino acid residue. More than 10 modified peptide homologues (20-26 aa length) of cathelicidin Pc-CATH1 were found to keep strong antimicrobial abilities. The possible relationships between bioactivities including antimicrobial and hemolytic abilities, components of secondary structure, hydrophobicity, amphipathicity, net charge, and sequence length were investigated. The current work provided suggestions for structural and functional modification of linear, α-helical antimicrobial peptides containing no disulfided bridges. DEFB18 and DEFB20 are found in the human β-defensin gene cluster by using a computational genomic search strategy. To investigate their biological functions, we constructed expression vectors in E.coli and got purified peptides by HPLC. DEFB18 and DEFB20 were found to contain ABTS radical scavenging ability, but they could not kill microorganisms including Escherichia coli, Staphylococcus aureus, Bacillus subtilis, and Candida albicans. |
| 语种 | 中文 |
| 公开日期 | 2013-04-22 |
| 源URL | [http://159.226.149.42:8088/handle/152453/7365]  |
| 专题 | 昆明动物研究所_动物毒素室 |
| 推荐引用方式 GB/T 7714 | 董丽. 抗菌肽Pc-CATH1结构与功能关系研究及人防御素DEFB18、DEFB20的原核表达[D]. 北京. 中国科学院研究生院. 2012. |
入库方式： OAI收割
来源：昆明动物研究所
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