抗菌肽在宿主防御中作用

抗菌肽广泛地存在于自然界中,其中许多抗菌肽具有直接抗微生物活性,能作用于G-、 G+细菌、真菌、寄生虫甚至是包膜病毒,并且在宿主先天免疫和适应性反应中有重要的调节作用。近来,越来越多的证据表明抗菌肽是有效的免疫辅助因子,能够与其他的众多免疫效应子协同作用,从而起始适应性免疫,促进伤口愈合,抑制前炎症反应以及诱导和调节细胞因子和趋化因子的产生。另外,随着抗菌肽作用机理逐渐被揭开,将这些内源性肽及其衍生物制成抗感染治疗药剂将会有广阔的应用前景。     

葫芦素的生态功能及其应用前景

葫芦素是一类高度氧化的四环三萜类植物次生代谢物质,是葫芦科30多属100多种植物的特征化合物。葫芦素在植物体内作为异源化学信息素起到保护葫芦科植物免受众多植食性动物和病原菌的侵害。另一方面,在葫芦科植物上取食的一些昆虫则利用葫芦素作为其寄主识别的信号物质。由于葫芦素特殊的化学结构和生物学活性,葫芦科植物与植食性动物之间的这种复杂关系已被广泛研究。总结葫芦素的分布、生物合成途径、及其对高等动物、昆虫和病原体的防御作用的研究概况。并对这类植物次生物质在有害生物综合治理中的应用及前景作了介绍与展望。     

抗菌肽的分布及其药用前景

抗菌肽在生物界分布广泛,从最低等的生物病毒、细菌到高等的动植物都有分布,抗菌肽不但广谱抗菌,能杀死耐药菌株,而且它的杀菌机制使病原菌不易发生耐药突变,有望开发为新一代抗菌药物,目前人类已在着手这方面的研究,并得到可喜的进展。     

昆虫抗菌肽研究现状

近年来鉴定了的化学结构的昆虫抗菌肽的数目有迅速上升的趋势,一些新型昆虫抗菌肽相继被分离纯化。不同结构的抗菌肽其抗菌特性及其抗菌谱存在着巨大差异,抗菌机制也不同。昆虫免疫与动物免疫机制既存在着区别也存在着某些相似性。     

抗菌肽及其临床应用前景

传统抗生素的广泛运用导致了耐药菌株的大量增加,迫切要求新型抗生素的出现。抗菌肽是广泛存在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。它不仅具有广谱杀菌作用,甚至能够抑杀真菌、寄生虫、含包膜病毒以及肿瘤细胞。抗菌肽通过与致病菌胞膜的结合形成跨膜离子通道,导致了细胞内外的离子交换最终引起细胞死亡。由于它作用迅速,选择性强,而且很少有耐药性的发生,很有可能成为新一代的抗菌药物。本文简述了抗菌肽的结构特点,抗菌作用机制,生物学功能和临床应用方面的最新进展以及进一步就抗菌肽作为新型抗生素所面临的问题进行了探讨。     

含抗菌肽酵母工程菌对肉仔鸡肠道菌群和免疫功能的影响

目的 研究含抗菌肽（Cec Md、3cs、3js）酵母工程菌对肉仔鸡肠道菌群和免疫功能的影响。方法 采用随机试验设计的方法,选用1日龄健康爱拔益加肉仔鸡400只,随机分成5组,每组设4个重复,每个重复20只鸡（雌雄各半）。空白对照组常规饮水,抗生素组在饮水中添加50 mg/L的泰乐菌素,抗菌肽实验组分别在饮水中添加8 mg/L含Cec Md、3cs和3js酵母工程菌,实验期42 d。结果 （1）Cec Md组的第1、4和5周及3cs组第3、5周的大肠埃希菌数量显著低于空白对照组（P<0.05）;Cec Md组和3cs组的第2至第6周及3js组的第2至第4周沙门菌数量显著低于空白对照组（P<0.05）;Cec Md组的第4至第6周及3cs组和3js组的第5周的乳杆菌数量显著高于空白对照组（P<0.05）;Cec Md组的第2、3、5周和6周及3cs组第5、6周及3js组的第3至第6周的双歧杆菌数量显著高于空白对照组（P<0.05）。（2）Cec Md组的第3、5周及3cs和3js组的第6周的IgA含量显著高于空白对照组（P<0.05）;Cec Md组和3js组的第3周的IgG含量显著高于空白对照组（P<0.05）。3js组的第1周的IgM含量显著高于空白对照组（P<0.05）,Cec Md组第4、5周的IgE含量显著高于空白对照组（P<0.05）。结论 含抗菌肽Cec Md、3cs和3js酵母工程菌可以抑制肉仔鸡肠道有害菌群的生长,促进其有益菌群的增殖,且可以改善肉仔鸡的免疫功能。     

抗菌肽及其工业应用前景

抗菌肽是生物体内经诱导产生的一种对抗外源性致病菌作用的防御性小分子多肽,广泛存在于动植物和微生物体内。其分子量一般在4000Da左右,带正电荷,由30～40个氨基酸组成。抗菌肽一般都具有耐热性,100℃温度下活性最长可保持30min以上。抗菌肽具广谱抗菌活性,通过破坏细胞膜等作用,可以抑制革兰氏阴性菌、革兰氏阳性菌、真菌,有些抗菌肽还具有抗原虫、病毒及抗癌功能。抗菌肽在工业应用中展示出了广阔的前景。     

热休克蛋白70的主要功能和应用前景

热休克蛋白70(HSP70)是生物体在各种应激条件下产生的蛋白之一,具有维持细胞自身稳定等多种生物学功能.随着研究的深入,在生物学的功能不断被发现的同时,HSP70的应用前景也变得越来越广泛.     

抗菌肽Lactoferricin生物学功能及其应用研究进展

概述了乳铁蛋白活性多肽(lactofericin)所具有的广谱抗菌、抗寄生虫、抗病毒、抗癌、抗氧化等多种生物学活性,讨论了lactnferricin的制备方法,并对lactnferricin作为饲料添加剂的应用前景作了初步探讨。     

昆虫抗菌肽研究现状

近年来鉴定了的化学结构的昆虫抗菌肽的数目有迅速上升的趋势,一些新型昆虫抗菌肽相继被分离纯化。不同结构的抗菌肽其抗菌特性及其抗菌谱存在着巨大差异,抗菌机制也不同。昆虫免疫与动物免疫机制既存在着区别也存在着某些相似性。     

Antibiotic peptides from higher eukaryotes: biology and applications.

Gene-encoded antibiotic peptides are increasingly being recognized as effector molecules of host defense in plants and animals. Studies of antimicrobial peptides are providing new insights into the dynamic interactions between microbes and their hosts, and are generating new paradigms for the pathogenesis and treatment of diseases. Because antimicrobial peptides of higher eukaryotes differ structurally from conventional antibiotics produced by bacteria and fungi, they offer novel templates for pharmaceutical compounds that could be effective against increasingly resistant microbes.     

Comparative immunological properties of enantiomeric peptides

Summary The immunogenicity of a peptide composed of only d-amino acids is compared with that of the corresponding l-peptide enantiomer. Following three administrations of 100 g of individual peptide formulated with different adjuvants (Freund's complete adjuvant, QS21, or alum) to BALB/c mice, guinea pigs and rabbits, the l-peptide elicited strong l-peptide-specific IgG antibody responses in all formulations, whereas the d-peptide-induced d-peptide-specific IgG antibodies in the Freund's complete adjuvant and QS21 formulations, but was nonimmunogenic in the alum formulation. Mouse T-cell lines induced by the d-peptide formulated in Freund's complete adjuvant were found to express significant amounts of IL-2 when they were stimulated by the d-peptide. When an equal amount of both enantiomers was mixed and administered in Freund's complete adjuvant, only an l-peptide-specific IgG antibody response was observed. These results suggest that (i) d-peptide is immunogenic when strong adjuvant is provided; (ii) the immune system has preferential recognition of l-amino acid peptide; and (iii) the d-peptide can elicit d-peptide-specific T-cell responses.     

Antibiotic activity of Leu-Lys rich model peptides

To develop novel antibiotic peptides useful as therapeutic drugs, short model peptides rich in Leu and Lys were designed by changing not only the net positive charge by Lys-deletion but also in the hydrophobic helix region by Leu-deletion from a peptide analogue of cecropin A (1–8)-magainin 2 (1–12) (CA-MA) known as P5. In particular, one peptide (P6), which was obtained by deleting Lys residues (positions 1, 3, 5, 9, 10, 13, 14) and Leu residues (positions 4, 7, 8, 11, 12, 15) and keeping Pro (position 6) and Trp (position 2), showed a strong antimicrobial and antitumor activity at 0.2–3.1 M without hemolytic activity against human erythrocyte cells. Furthermore, P6 causes significant morphological alterations of the bacterial surfaces at 3.1 M as shown by scanning electron microscopy.     

Human antimicrobial peptides: analysis and application

Antimicrobial peptides are innate host defense molecules that have a direct effect on bacteria, fungi and enveloped viruses. They are found in evolutionarily diverse species ranging from prokaryotes and plants to invertebrate and vertebrate animals. Humans express several families of antimicrobial peptides in myeloid cells and on various epithelial surfaces where they are poised to defend against pathogens. Recently, antimicrobial peptides from animals and plants have served as templates for the design of new therapeutic antibiotics. This review provides an introduction to the biology of human antimicrobial peptides, followed by a more detailed discussion of their isolation from tissues and biological fluids, their purification by gel electrophoresis and chromatography and assays of their antimicrobial activities.     

Schistosome surface antigens: developmental expression and immunological function

It has long been held as axiomatic that antigens exposed on the surfaces of parasitic organisms are primary targets of protective immune responses. It is becoming apparent that not all protective schistosome antigens are surface antigens and that not all surface antigens are necessarily targets of protective immunity. Andy Simpson suggests that one of the factors that determines the immunological function of surface antigens may be developmental expression.     

三叶肽：从结构到功能

三叶结构域是一段由38－39个氨基酸组成的多肽序列,其中包含6个高度保守的半胱氨酸残基,这6个半胱氨酸残基以1－5,2－4,3－6的交联方式形成三对二硫,窝囊鑫肽链折叠成特征性的三叶结构。已发现的哺乳动物三叶肽有三种：pS1、SP及ITF。三叶肽通常位于消化道腔面的粘膜层,具有保护和修复功能,在维持粘膜的完整性中发挥着重要作用。     

Antibiotic resistance peptides: interaction of peptides conferring macrolide and ketolide resistance with Staphylococcus aureus ribosomes: conformation of bound peptides as determined by transferred NOE experiments

Two antibiotic resistance peptides, the E-peptide (MRLFV) and the K-peptide (MRFFV) conferring macrolide and ketolide resistance, respectively, were studied in the complex state with bacterial Staphylococcus aureus ribosomes. Interactions of antibiotic resistance peptides with ribosomes were investigated using two-dimensional transferred nuclear Overhauser effect spectroscopy (TRNOESY), suggesting that the peptide-ribosome interaction was associated with the low-affinity binding level. K-Peptide displayed a significantly better response in TRNOEs NMR experiments, in agreement with a better overall antibiotic activity of ketolides. This difference highlights a mimetic effect displayed by the E- and K-peptides. This study shows that conformation plays an essential role for the affinity binding site and, thus, for the resistance mechanism. Specific conformations were preferred in the bound state; their superimposition exhibited a similar cyclic peptidyl chain, while the side chain region varies. The F4 phenyl moiety in E-peptide has moved out of the turn region compared to its folding in the ketolide resistance peptide. In the K-peptide binding surface, the F4 aromatic chain is maintained by stacking with the guanidyl group of the R2 residue providing a particular hydrophobic and globular fragment, which may be important for the ketolide resistance peptide mode of action. Additionally, T(2) (CPMG) measurements were used to characterize equilibrium binding of antibiotic resistance peptides to bacterial ribosomes. The results bring to the fore E- and K-peptide competition with antibiotics for binding to the ribosomes. Their specific interaction and their competitive effects reveal a novel aspect of interaction of resistance peptides with ribosomes and suggest new insights about their mode of action. The resistance mechanism may imply two steps, a competitive effect of the resistance peptide for the macrolide (or ketolide) binding site followed by a "bottle brush" effect in which the drug and the peptide are driven out their binding site on the ribosome.     

The immunological function of allosuckling

Young mammals are unable to mount an efficient immune response against invading pathogens. Until their immune system is mature mothers transmit to their young immunological compounds during lactation. Given that genetic and foster mothers can assume this protective role, we propose that young mammals may gain immunological benefits by suckling more than one nursing female, a behaviour referred to as "allosuckling". This hypothesis has so far not been considered as a potential explanation for the propensity of young mammals to suckle foster mothers. However, pathogen transmission through milk during allosuckling may reduce the immunological net benefit that young gain, and furthermore allosuckling may increase pathogen transmission between foster and genetic mothers implying costs of allosuckling for all participants. Here, we develop the immunological function of allosuckling hypothesis (IFA) as a potential explanation for intra-and interspecific variation in allosuckling frequency. We present published experimental evidence for the assumption that immunological benefits of allosuckling depend on the immunological status of the offspring, the foster and the genetic mothers. Finally, we give predictions arising from the IFA hypothesis and propose that the IFA may provide a new explanation as to why neonates suckle various females and why foster females often refuse to nurse nonoffspring.