肽类抗生素选择性作用机制研究进展与评价

肽类抗生素(peptide antibiotics)是一类广泛存在于生物体内具有抵抗外界微生物侵害、消除体内突变细胞的小分子多肽,即抗菌肽。肽类抗生素不仅具有高效广谱的抗微生物作用,还参与免疫应答、伤口愈合、细胞因子释放、白细胞趋化等反应过程,是一类广谱、安全、不易产生耐药菌的抗生素。不同抗菌肽对不同类型靶细胞表现出活性上的巨大差异,即抗菌肽作用的选择性,这种作用的选择性受到多种因素的影响。探讨抗菌肽作用于细胞的机制,特别是选择性作用的机制将有助于设计出活性更高的新型肽类抗生素。本文主要从细胞表面结构特异性、抗菌肽自身结构特点阐述近年来抗菌肽活性与选择性作用研究的新进展。     

肽类抗生素的研究进展

肽类抗生素是一类广泛存在于自然界各种生物中的活性肽,具有抗细菌、真菌、病毒、原虫,抑杀癌细胞,调节免疫等活性,有望成为继传统抗生素之后一类新的治疗药物。此文对肽类抗生素的制备、结构、活性、作用机制以及在医药工业方面的研究与应用进行了综述。     

肽类抗生素的研究

过去50年被称为“抗生素时代”,天然、半合成或全合成抗菌药物成功地抵抗了威胁生命的感染.然而,该时代可能即将结束,至少抗生素的功效正逐渐降低.1994年,世界卫生组织有关抗生素耐药性监测的科学研究小组报道,无论在发展中国家还是发达国家抗菌药物的耐药性已成为严重的公共卫生问题.耐药水平以一种危险的速率一直在增长,预计在未来会以相似甚至更快的速率增长,同时抗菌药物丧失其功效.该问题正受到广泛重视.     

噻唑肽类抗生素研究进展

多数噻唑肽类抗生素能与细菌的50s核糖体亚基相结合抑制其蛋白质的合成，有些还能抑制肾素-血管紧张素系统。产生抗性的链霉菌可以合成一种甲基转移酶，将自身的23SrRNA1067位点上的腺苷2＇-OH转化成2＇-CH3，阻碍噻唑肽类抗生素与50s核糖体亚基结合。通过研究噻唑肽类化合物生物合成基因发现，产生该类抗生素的劳伦链霉菌和活力链霉菌中均含有编码非核糖体合成酶的基因．因此噻唑肽类化合物极可能是由非核糖体肽合成酶（NRPS）根据巯基模板机制装配而成。本文重点就噻唑肽类化合物的作用机制、抗性机制以及合成途径的研究进展进行综述。     

环脂肽类抗生素研究进展

2003年新抗生素达托霉素的上市，使环脂肽类化合物成为医药研发的热点。本文跟踪了国外环脂肽类抗生素研究的最新进展，从结构特征、物化性质、抗菌活性，构效关系以及生物合成等方面对该类抗生素进行了小结，并对达托霉素的药效学研究和临床应用作了重点介绍。     

含硫多肽类抗生素那西肽的研究进展

那西肽（nosiheptide）是一类由活跃链霉菌（Streptomyces actuosus）产生的新型环保含硫多肽类抗生素。本文就其结构与理化特性,生物学功能及作用机制,生产,提取工艺,测定方法,安全性及应用等方面进行了综述,对产那西肽的结构基因,菌种改良方面的研究进行了总结,对那西肽后续的研究进行了展望。     

尿苷肽类抗生素生物合成研究进展

尿苷肽类抗生素是一类具有相同母核结构的化合物,其化学结构独特、作用机制新颖、抗菌谱窄,是寻找新型低毒、窄谱抗菌药物的先导化合物或候选药物的最佳选择之一。本文介绍了尿苷肽类抗生素的化学结构特征以及构效关系,着重介绍了其生物合成机制的最新研究进展。尿苷肽类抗生素肽链的合成由非核糖体肽合成酶（non-ribosomal peptide synthetase,NRPS）以非线性机制催化完成,肽链的组装始于中心模块2,3-二氨基丁酸（2,3-diaminobutyric acid,DABA）,其后的延伸包括N端氨基酸或二肽与DABAβ-氨基间的缩合,以及C端的脲二肽与DABAα-氨基间的缩合。3′-脱氧-4′,5′-烯酰胺尿苷由尿苷经过3步反应转化而来,并在NRPS的催化下与四肽或五肽缩合形成尿苷肽类抗生素。尿苷肽类抗生素生物合成机制的阐明为利用组合生物合成技术获得新结构的尿苷肽类化合物奠定了基础。     

金属离子和磷酸盐对脂肽类抗生素FW99608生物合成的影响

不同金属离子和磷酸盐对脂肽类抗生素 FW996 0 8产生菌 Streptomyces sp.FIM996 0 8的发酵效价有不同影响。在有机发酵培养基中加入一定浓度 Cu2 +、Co2 +、Zn2 +以及 K2 SO4 能明显提高 Streptomycessp.FIM996 0 8的发酵效价并促进其菌丝生长。然而 ,Ca CO3和 K2 HPO4 · 3H2 O明显抑制脂肽类抗生素 FW996 0 8的生物合成。     

氨基糖苷类抗生素作用机制研究进展

氨基糖苷类抗生素作为一种杀菌性抗菌药物,具有抗菌谱广、杀菌完全等特点,其作用机制主要是通过抑制细菌蛋白质的合成而杀死细菌。随着新技术、新方法的应用,杀菌性抗生素普遍性地通过产生羟基自由基杀死细菌及其他作用途径也被挖掘。本文简要综述氨基糖苷类抗生素的作用机制,并对新型氨基糖苷类抗生素的开发进行展望。     

重组人肽抗生素hPAB-β及其突变体的活性测定与筛选

目的 测定重组人肽抗生素hPAB—β及其突变体的抗菌活性，筛选理想的活性分子。方法 应用平板法和MIC测定法检测重组表达的hPAB—β及突变体hPAB—β38、hPAB—β34对8株实验室保存菌株及10株临床分离菌株的杀菌能力。并以化学合成的肽抗生素hPAB—β作对照；根据各目的分子抗菌能力的强弱，筛选理想的目标分子，并分析突变体结构的变化对其功能的影响。结果 重组hPAB—β及突变体hPAB—β38与化学合成的天然分子抗菌活性相当．对革兰氏阳性菌的MIC在125～250μg／ml之间，对革兰氏阴性菌的MIC在31～125μg／ml范围内；突变体hPAB—β34活性下降4倍左右；结构分析表明hPAB—β38与hPAB—β参与二级结构中α螺旋和β片层构成的氨基酸残基完全相同，而hPAB-β34则有显著不同，α螺旋少了2个残基，3个β片层中除β2与hPAB—β相同外，β1和β3的构成均多2个残基，推测hPAB—β34二级结构的改变是其活性降低的主要原因。结论 重组肽抗生素hPAB—β具有抗菌活性，删除3个端残基的突变体hPAB—β38活性不变，可作为hPAB—β走向临床应用的一个新侯选者。     

多肽抗生素研究进展

多肽抗生素是生物界中广泛存在的一类生物活性小肽 ,一般具有抗细菌或真菌的作用 ,有些还具有抗原虫、病毒或癌细胞的功能。按照化学结构的不同 ,多肽抗生素可分为5类 :①具有螺旋结构的线性多肽 ;②富含某种氨基酸的线性多肽 ;③含有一个二硫键的多肽 ;④含有两个或两个以上二硫键的多肽 ;⑤羊毛硫抗生素。根据作用机理的不同 ,多肽抗生素又可分为裂解细胞膜的裂解肽和非裂解肽。多肽抗生素已经开始用于医药、食品和植物抗病基因工程等方面 ,并且有着很大的发展潜力。     

Design and synthesis of a novel peptide for selective detection of cancer cells

Using a minimalist approach, an 11‐residue peptide (Peptide 1 ) tagged with rhodamine fluorophore was designed and synthesized for selective detection of cancer cells. Peptide 1 contains RGD and NGR motifs to bind, respectively, integrins and aminopeptidase CD13, which are over expressed in cancer cells. Surface tension measurements revealed that peptide 1 possess surface‐active property owing to the overall hydrophobicity and cationic nature of the peptide. Peptide 1 displays cancer cell‐selective binding at ≤5.0 µM concentrations, while peptide 2 (randomized sequence of 1 ) shows non‐selective binding to normal and cancer cells. Fluorescence microscopy and FACS analysis demonstrated the intracellular localization of peptide 1 in three different cancer cell lines, confirming the role of RGD and NGR motifs. Cytotoxicity assay exhibited the viability of normal and cancer cells up to 100 µM concentrations of peptide 1 . Steady‐state fluorescence measurements disclosed the preferential interactions of the peptide 1 with anionic POPC/POPG bilayers rather than with zwitterionic POPC lipid bilayers. Circular dichroism studies showed minimal changes in the secondary structure of peptide 1 upon binding with the anionic lipid bilayers. Peptide 1 is largely unordered, non‐toxic, and useful for identification of cancer cells. Peptide 1 provides a template for designing drug‐loaded peptides for targeted delivery into cancer cells.     

PCR-based site-specific mutagenesis of peptide antibiotics FALL-39 and its biologic activities

AIM: To construct PGEX-1λT-FALL-39 expression vector and its mutant vector, and study the relationship of function and structure. METHODS: A cDNA encoding mature FALL-39 was cloned from SPCA-1 cell mRNA and the prokaryotic expression vector PGEX-1λT-FALL-39 was constructed. Two kinds of polymerase chain reaction(PCR) for the site-direction mutagenesis were used to construct FALL-39 mutant expression vector, FALL-39-Lys-32 and FALL-39-Lys-24. Minimal effective concentration, minimal inhibitory concentration, and minimal bactericidal concentration were used to assay the antibacterial activities of these peptides. Effects of different solution on the antibacterial activity of FALL-39 and FALL-39-Lys-32 were observed by CFU determination. The hemolytic effects of these peptides were also examined on human red blood cells. RESULTS: Two site-specific mutants FALL-39-Lys-32 and FALL-39-Lys24 were obtained by PCR-induced mutagenesis. In comparison with two-step PCR which required two pairs of primers, one step PCR which required one pair of primers is a simple and efficient method for the PCR based site-specific mutagenesis. Using the prokaryotic expression system, the E coli-based products of recombinant FALL39 and its mutant peptides were also obtained. The antibacterial assay showed that FALL-39-Lys-32 and FALL-39-Lys24 were more potential in the antibacterial activity against E coli ML35p and Pseudomonas aeruginosa ATCC27853 than that of FALL-39, and no increase in hemolysis was observed at the antibacterial concentrations, The antibacterial activity of FALL-39-Lys-32 against E coli was more potent than that of FALL-39 in NaCl-containing LB medium, while its activity was almost the same as FALL-39 in SO4^2 containing Medium E. CONCLUSION: PCR-based mutagensis is a useful model system for studying the structure and function relationship of antimicrobial peptides. Keeping α-helical conformation of FALL-39 and increasing net positive charge can increase the antibacterial activity of FALL-39 without increasing hemolysis at the antibacterial concentrations.     

家蝇抗菌肽抗菌活性及抗菌机制的初步研究

目的　研究家蝇抗菌肽的抗菌活性及抗菌机制。方法　用损伤感染的方法诱导家蝇幼虫表达抗菌肽 ,通过 Sephadex过滤层析和 HL PC技术纯化提取 ,用平板法和稀释法作抗菌活性试验 ,并用电子扫描技术研究抗菌肽的抗菌机制。结果　家蝇抗菌肽对铜绿假单胞菌、大肠埃希氏菌、耐甲氧西林金黄色葡萄球菌( MRSA)均有明显的抗菌活性。大肠埃希氏菌与 5 0 μg/ml的纯化抗菌肽溶液一起 37℃孵育 6 0 min后 ,大肠埃希氏菌不能存活。经电镜扫描观察发现 ,细菌的细胞膜出现破损和穿孔现象。结论　家蝇抗菌肽具有明显的广谱抗菌活性 ,对阴性杆菌和阳性球菌均有杀伤作用。抗菌肽的抗菌机制是通过破坏细菌的细胞膜而杀伤细菌的     

新型抗生素的研究进展及研发趋势探讨

抗生素是目前应用和研发最活跃的一类药物,本文就新型抗生素-抗菌肽的最新研究进展进行了综述,并对该类抗生素的研发趋势进行了探讨.     

脑钠肽镇痛作用及机制的研究

目的：研究脑钠肽（ｂｒａｉｎｎｅｔｒｉｕｒｅｔｉｃｐｅｐｔｉｄｅ，ＢＮＰ）的镇痛作用及机制。方法：在小鼠热板、扭体和甲醛试验上，分别观察用药后舔足潜伏期、扭体数及疼痛评分的变化。一氧化氮（ＮＯ）用ｇｒｅｅｎ法测定。结果：ＢＮＰ（２５，５０，１００μｇ·ｋｇ－１，ｉｐ）能显著延长小鼠舔足潜伏期，并呈量效关系，其ｉｐＥＤ５０为３８．６μｇ·ｋｇ－１；ｉｐ２５、５０μｇ·ｋｇ－１ＢＮＰ显著减少小鼠扭体数和脑组织中ＮＯ含量；ｉｐ５０μｇ·ｋｇ－１和ｉｃｖ２μｇ·ｋｇ－１ＢＮＰ均可显著抑制甲醛致小鼠疼痛，降低疼痛评分，进一步发现ＢＮＰ的镇痛作用可被ＥＧＴＡ加强，ＣａＣｌ２拮抗，但维拉帕米可部分逆转ＣａＣｌ２对ＢＮＰ镇痛的拮抗。结论：ＢＮＰ有显著镇痛作用，其镇痛作用可被Ｃａ２＋影响。     

Possible interaction of quinolone antibiotics with peptide transporter 1 in oral absorption of peptide‐mimetic drugs

The study investigated whether quinolone antibiotics inhibit the PEPT1‐mediated uptake of its substrates. Among the quinolones examined, lomefloxacin, moxifloxacin (MFLX) and purlifloxacin significantly inhibited the uptake of PEPT1 substrate phenylalanine‐Ψ(CN‐S)‐alanine (Phe‐Ψ‐Ala) in HeLa/PEPT1 cells to 31.6 ± 1.3%, 27.6 ± 2.9%, 36.8 ± 2.2% and 32.6 ± 1.4%, respectively. Further examination showed that MFLX was an uncompetitive inhibitor, with an IC₅₀ value of 4.29 ± 1.29 mm . In addition, MFLX significantly decreased the cephalexin and valacyclovir uptake in HeLa/PEPT1 cells. In an in vivo study in rats, the maximum plasma concentration (C_max) of orally administered Phe‐Ψ‐Ala was significantly decreased in the presence of MFLX (171 ± 1 ng/ml) compared with that in its absence (244 ± 9 ng/ml). The area under the concentration–time curve (AUC) of orally administered Phe‐Ψ‐Ala in the presence of MFLX (338 ± 50 ng/ml · h) tended to decrease compared with that in its absence (399 ± 75 ng/ml · h). The oral bioavailability of Phe‐Ψ‐Ala in the presence and absence of MFLX was 41.7 ± 6.2% and 49.2 ± 9.2%, respectively. The results indicate that administration of quinolone antibiotics concomitantly with PEPT1 substrate drugs may potentially result in drug–drug interaction. Copyright © 2016 John Wiley & Sons, Ltd.