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1.
鱼精蛋白是一类天然的阳离子抗菌肽,具有广谱抑菌活性。鱼精蛋白主要是通过破坏细菌的细胞壁、细胞膜及改变细胞的渗透性等途径抑制甚至杀死细菌细胞。在鱼精蛋白抑制细菌的同时,细菌也产生多种机制对抗鱼精蛋白。温度、pH、阳离子和EDTA等多种理化因子影响鱼精蛋白对细菌的抑制效果。由于鱼精蛋白在抑菌防腐方面的众多优势,目前已成为非常有发展前景的食品防腐剂。  相似文献   

2.
家蝇幼虫抗菌肽MDL-2对细菌细胞渗透性及代谢功能影响   总被引:2,自引:0,他引:2  
研究了家蝇幼虫抗菌肽MDL-2与细菌相互作用时,抗菌肤MDL-2对细菌细胞壁的溶解作用、细胞膜渗透性和代谢的影响.抗菌肽MDL-2在抗菌过程中首先与细菌的细胞壁相互作用,使其破裂,抗菌肽对革兰氏阴性细菌大肠杆菌细胞壁的作用有浓度依赖性,而对革兰氏阳性细菌金黄色葡萄球菌MDL-2在较低的浓度时即可发生细胞壁破坏作用;抗菌...  相似文献   

3.
测定了鱼精蛋白对常见食品污染菌的抑制效果和最低抑菌浓度 (MIC) ;通过鱼精蛋白与甘氨酸、醋酸钠复合 ,或与冷冻并用等方法 ,提高了鱼精蛋白对革兰氏阴性菌的抗菌活性  相似文献   

4.
烟曲霉(Aspergillus fumigatus)是一种腐生的丝状真菌,其营养菌丝存在于土壤、空气和有机物质中,是免疫功能严重受损患者最常见的感染性死亡原因之一。烟曲霉细胞壁是一个动态的结构,这种动态结构成为其对抗环境的主要防线[1]。由于支持烟曲霉生长和繁殖的自然过程的变化或者所处环境应激反应,其细胞壁会经历持续的生物合成和重塑[2]。研究发现,许多基因可通过改变细胞壁成分含量而使细胞壁结构重塑。烟曲霉分生孢子的形成也会伴随着孢子细胞壁的重塑[3-4]。另外,相关基因、转录因子会控制细胞壁的生物合成,调节烟曲霉细胞壁的稳态[5-6]。分生孢子发展形成菌丝的过程、基因的正确定位对烟曲霉的致病相当关键[7]。抵抗宿主环境压力的机械强度主要由其细胞壁提供,所以细胞壁的破坏对菌丝形态有深远的影响。鉴于烟曲霉细胞壁在真菌生理学中的重要作用,它被认为是抗真菌药物的一个极好的靶点。  相似文献   

5.
铜绿假单胞菌多重耐药基因的筛选及鉴定   总被引:1,自引:0,他引:1  
[目的]研究铜绿假单胞菌中与耐药性相关的基因.[方法]筛选转座突变体文库中对多种抗菌药物敏感的突变体,通过随机PCR、核苷酸测序及序列比对确定突变体中转座子的插入位点及其破坏的基因.[结果]筛选得到2株对多种抗菌药物敏感的突变体,其中被破坏的基因分别为功能未知的新基因PA2580和PA2800.[结论]PA2580和PA2800可能分别通过参与细胞氧化还原作用和细胞壁合成进而与铜绿假单胞菌耐药性相关.  相似文献   

6.
噬菌体溶壁酶研究进展   总被引:1,自引:0,他引:1  
溶壁酶是噬菌体在感染末期表达的蛋白质,可水解细菌的细胞壁,使子代噬菌体释放出来。研究表明,溶壁酶在体外能高效地杀死细菌,同样对感染细菌的模型动物有很好的治疗作用。因此,溶壁酶是一种新型的抗菌物质,具有广阔的应用前景。溶壁酶通过水解细菌细胞壁肽聚糖上糖与肽间的酰胺键或肽内氨基酸残基间的连键,从而使细菌裂解。溶壁酶分子由结合功能域和催化功能域两部分组成,其晶体结构使之具有对细胞壁肽聚糖水解的高效性和特异性。对噬菌体溶壁酶的体内外抗菌作用、抗菌机理、晶体结构等最新研究成果及其应用前景进行了综述。  相似文献   

7.
近年来的研究发现 ,抗菌蛋白在生物体非专一性防御系统有着重要的作用 ,已有数十种具有抗菌活性的多肽被分离 ,这些多肽可大致分为 3类 ,即含分子内二硫桥的抗菌肽 ;具有双亲α 螺旋结构的抗菌肽 ;以及富含某种氨基酸残基的抗菌肽[1 ] ,一般来说 ,这些抗菌肽具有分子量小 ,稳定性好 ,无细胞毒性 ,抗菌谱广等特点。多种抗菌肽的一级结构和二级结构已经确定[2 ] ,但作用机理仍不明了。一般认为可能存在两种作用模式 ,即 1)通过肽 脂膜相关作用杀菌 ;2 )通过受体介导的识别过程起作用[1 ] 。CecropinB是一种较早从家蚕中分离得到 ,由 …  相似文献   

8.
近年来的研究发现,抗菌蛋白在生物体非专一性防御系统有着重要的作用,已有数十种具有抗菌活性的多肽被分离,这些多肽可大致分为3类,即含分子内二硫桥的抗菌肽;具有双亲a-螺旋结构的抗菌肽;以及富含某种氨基酸残基的抗菌肽[1],一般来说,这些抗菌肽具有分子量小,稳定性好,无细胞毒性,抗菌谱广等特点.多种抗菌肽的一级结构和二级结构已经确定[2],但作用机理仍不明了.一般认为可能存在两种作用模式,即1)通过肽-脂膜相关作用杀菌;2)通过受体介导的识别过程起作用[1].  相似文献   

9.
通常认为多泡体是原生质体和胞饮作用中的一种特殊的细胞结构, 是由细胞质膜的内陷所起源. 然而多泡体的起源、功能及其分泌途径以及与高尔基体和细胞壁的关系等问题一直存有争论. 本文应用动物细胞的58K蛋白的单克隆抗体、免疫印记、激光共聚焦显微技术在拟南芥和贯叶连翘愈伤组织中成功定位了类58K蛋白. 免疫电子显微镜的观察结果显示, 类58K蛋白存在于拟南芥愈伤组织细胞的高尔基体库槽、分泌泡、多泡体、细胞壁和液泡中. 由此我们认为多泡体与细胞壁和液泡发育的关系十分密切, 它起源于高尔基体并以分泌泡的形式将高尔基体所合成的物质运送至细胞壁和液泡. 所以多泡体的分泌途径可能是运送高尔基体合成的物质到细胞壁, 属于胞吐形式; 也有可能是运送相关物质到液泡中参与液泡的发育, 属于胞饮形式. 这主要取决于多泡体所运送物质的种类以及它将这些物质运往何处. 因此多泡体的分泌途径很可能有多种形式. 研究结果也显示应用动物细胞58K蛋白抗体可以定位植物细胞中的类58K蛋白, 说明植物细胞中存在与动物细胞相类似的蛋白.  相似文献   

10.
产朊假丝酵母细胞壁33 ku蛋白的功能研究   总被引:3,自引:0,他引:3  
通过胰蛋白酶和枯草杆菌蛋白酶对产朊假丝酵母Candida utilis细胞壁的酶解,发现一种分子质量为33 ku的酵母细胞壁主要结构蛋白. 研究显示,在细胞壁上这种蛋白质与细胞壁绝大多数蛋白质成分不同, 它不被胰蛋白酶水解,但对枯草杆菌蛋白酶的作用敏感.33 ku蛋白存在于酵母菌整个对数生长期的细胞壁中,特别是在对数早期细胞壁中,它是唯一的对胰蛋白酶作用不敏感的蛋白质成分.实验证明,该蛋白质对维系酵母细胞壁骨架成分葡聚糖的相互连接和细胞壁的完整结构,具有重要作用,是一种重要的酵母细胞壁嵌合蛋白.  相似文献   

11.
The innate resistance of plants and animals to microbial infection is mediated in part by small cationic peptides with antimicrobial activity. We assessed the susceptibility of the alfalfa symbiont Sinorhizobium meliloti to the model antimicrobial peptide protamine. Twenty-one Tn5-induced mutants showing increased sensitivity to protamine were isolated, and nine were further characterized in detail. These nine mutants carried distinct transposon insertions that affected a total of seven different genes. Three of these genes are involved in exopolysaccharide and beta-(1,2)-glucan biosynthesis (exoT, exoU and ndvB), three other genes are implicated in nitrogen metabolism, such as a putative dyhidropyrimidinase, hutU and ureF, and the last gene exhibited similarity to the ATP binding cassette family of membrane transporters. Symbiotic defects ranging from severe to moderate were displayed by some of the protamine-hypersensitive mutants suggesting that S. meliloti possess active mechanisms to counteract hypothetical cationic peptides that may be produced by its host plant.  相似文献   

12.
With the steady rise in the number of antibiotic-resistant Gram-positive pathogens, it has become increasingly important to find new antibacterial agents which are highly active and have novel and diversified mechanisms of action. Two classes will be discussed here: the cationic antimicrobial peptides, which are amphiphilic in nature, targeting membranes and increasing their permeability; and lipopeptides, which consist of linear or cyclic peptides with an N-terminus that is acylated with a fatty acid side chain. One member of the cyclic lipopeptide family, the anionic molecule daptomycin, has been extensively studied and is the major focus of this review. Models will be presented on its mode of action and comparisons will be made to the known modes of action of cationic antimicrobial peptides and other lipopeptides.  相似文献   

13.
With the steady rise in the number of antibiotic-resistant Gram-positive pathogens, it has become increasingly important to find new antibacterial agents which are highly active and have novel and diversified mechanisms of action. Two classes will be discussed here: the cationic antimicrobial peptides, which are amphiphilic in nature, targeting membranes and increasing their permeability; and lipopeptides, which consist of linear or cyclic peptides with an N-terminus that is acylated with a fatty acid side chain. One member of the cyclic lipopeptide family, the anionic molecule daptomycin, has been extensively studied and is the major focus of this review. Models will be presented on its mode of action and comparisons will be made to the known modes of action of cationic antimicrobial peptides and other lipopeptides.  相似文献   

14.
Antimicrobial peptides are small amphiphilic proteins found in animals and plants as essential components of the innate immune system and whose function is to control bacterial infectious activity. In order to accomplish their function, antimicrobial peptides use different mechanisms of action which have been deeply studied in view of their potential exploitation to treat antibiotic-resistant bacterial infections. One of the main mechanisms of action of these peptides is the disruption of the bacterial membrane through pore formation, which, in some cases, takes place via a monomer to oligomer cooperative transition. Previous studies have shown that lipid composition, and the presence of exogenous components, such as cholesterol in model membranes or carotenoids in bacteria, can affect the potency of distinct antimicrobial peptides. At the same time, considering the membrane as a two-dimensional material, it has been shown that membrane composition defines its mechanical properties which might be relevant in many membrane-related processes. Nevertheless, the correlation between the mechanical properties of the membrane and antimicrobial peptide potency has not been considered according to the importance it deserves. The relevance of these mechanical properties in membrane deformation due to peptide insertion is reviewed here for different types of pores in order to elucidate if indeed membrane composition affects antimicrobial peptide activity by modulation of the mechanical properties of the membrane. This would also provide a better understanding of the mechanisms used by bacteria to overcome antimicrobial peptide activity.  相似文献   

15.
The antimicrobial efficacy of protamine on Listeria monocytogenes and Escherichia coli was evaluated at concentrations from 50 to 10 000 microgram ml-1 and pH levels from 5.5 to 8.0. The minimum inhibitory concentrations decreased with increasing pH. Protamine inhibited E. coli at all pH values while L. monocytogenes was inhibited at pH 6.5 and above. The antimicrobial efficacy of protamine decreased in the presence of negatively charged gelatine B but remained almost unchanged with addition of the positively charged gelatine A. Binding studies showed that the amount of protamine adsorbed to culture media components in tryptic soy broth and bacterial cells increased with increasing pH values. The increased efficacy of protamine at alkaline pH may be explained on the basis of an increase in electrostatic affinity for the cell surface of target cells. E. coli produced a protamine-degrading enzyme, however, was still susceptible to protamine.  相似文献   

16.
Although biocides have been used for a century, the number of products containing biocides has recently increased dramatically with public awareness of hygiene issues. The antimicrobial efficacy of biocides is now well documented; however, there is still a lack of understanding of their antimicrobial mechanisms of action. There is a wide range of biocides showing different levels of antimicrobial activity. It is generally accepted that, in contrast to chemotherapeutic agents, biocides have multiple target sites within the microbial cell and the overall damage to these target sites results in the bactericidal effect. Information about the antimicrobial efficacy of a biocide (i.e. the eta-value) might give some useful indications about the overall mode of action of a biocide. Bacteriostatic effects, usually achieved by a lower concentration of a biocide, might correspond to a reversible activity on the cytoplasmic membrane and/or the impairment of enzymatic activity. The bacteriostatic mechanism(s) of action of a biocide is less documented and a primary (unique?) target site within the cell might be involved. Understanding the mechanism(s) of action of a biocide has become an important issue with the emergence of bacterial resistance to biocides and the suggestion that biocide and antibiotic resistance in bacteria might be linked. There is still a lack of understanding of the mode of action of biocides, especially when used at low concentrations (i.e. minimal inhibitory concentration (MIC) or sublethal). Although this information might not be required for highly reactive biocides (e.g. alkylating and oxidizing agents) and biocides used at high concentrations, the use of biocides as preservatives or in products at sublethal concentrations, in which a bacteriostatic rather than a bactericidal activity is achieved, is driving the need to better understand microbial target sites. Understanding the mechanisms of action of biocides serves several purposes: (i) it will help to design antimicrobial formulations with an improved antimicrobial efficacy and (ii) it will ensure the prevention of the emergence of microbial resistance.  相似文献   

17.
以鲤鱼的成熟精巢为原料,经0.15 mol/L NaCl溶液浸提,硫酸解离,并分别经乙醇、丙酮分离提取鱼精蛋白。测定了鱼精蛋白对细菌和真菌的最低抑制浓度以及在不同pH条件下的抑菌特性,试验结果表明鱼精蛋白具有较好的热稳定性,与EDTA复合使用可以增强抑菌效果,在酱油中可以代替苯甲酸的防腐作用。  相似文献   

18.
Traditional Chinese medicines have been used for thousands of years and are still being used as one of the regular treatments for many diseases. However, their mechanisms were still unknown. In this investigation, a possible procedure combining metabonomics and principal component analysis to investigate antibacterial modes of action and find main antimicrobial component in traditional Chinese medicine, Aquilegia oxysepala, is developed. Metabolic profiles of Staphylococcus aureus treated with nine antibiotics of known modes of action and with A. oxysepala were acquired by HPLC/DAD/ESI-MS. After statistical processing by principal components analysis on metabolic profiles, two conclusions could be drawn: (1) the target of A. oxysepala may be similar to that of lincolmensin, erythromycin, chloromycetin, streptomycin, and acheomycin, whose targets are protein; (2) its bioactive component playing main antimicrobial roles on S. aureus may be maguoflorine.  相似文献   

19.
The mucosal immune network is a crucial barrier preventing pathogens from entering the body. The network of immune cells that mediates the defensive mechanisms in the mucosa is likely shaped by chemokines, which attract a wide range of immune cells to specific sites of the body. Chemokines have been divided into homeostatic or inflammatory depending upon their expression patterns. Additionally, several chemokines mediate direct killing of invading pathogens, as exemplified by CCL28, a mucosa-associated chemokine that exhibits antimicrobial activity against a range of pathogens. CXCL17 was the last chemokine ligand to be described and is the 17th member of the CXC chemokine family. Its expression pattern in 105 human tissues and cells indicates that CXCL17 is a homeostatic, mucosa-associated chemokine. Its strategic expression in mucosal tissues suggests that it is involved in innate immunity and/or sterility of the mucosa. To test the latter hypothesis, we tested CXCL17 for possible antibacterial activity against a panel of pathogenic and opportunistic bacteria. Our results indicate that CXCL17 has potent antimicrobial activities and that its mechanism of antimicrobial action involves peptide-mediated bacterial membrane disruption. Because CXCL17 is strongly expressed in bronchi, we measured it in bronchoalveolar lavage fluids and observed that it is strongly upregulated in idiopathic pulmonary fibrosis. We conclude that CXCL17 is an antimicrobial mucosal chemokine that may play a role in the pathogenesis of interstitial lung diseases.  相似文献   

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