小分子肽-肿瘤抑素19肽纯化及抗肿瘤活性研究

目的:利用已构建好的肿瘤抑素抗肿瘤活性肽-19肽高效表达基因重组菌纯化19肽,并进行抗肿瘤活性检测。方法:经几丁质亲和层析柱纯化出19肽,SDS-PAGE聚丙烯酰胺电泳后用Bradford法测其浓度,进行体内活性检测。结果:19肽可促进H22小鼠肝癌细胞死亡,血管数量减少,抑瘤率达48．46%。结论:得到了具有抗肿瘤活性的肿瘤抑素相关肽—19肽,为肿瘤抑素的作用机制研究和肿瘤的临床治疗奠定了基础。     

海藻肽的化学结构特征和活性作用研究进展

海藻中的肽类化合物具有显著的生物活性和药理作用,对其氨基酸序列及活性作用的研究已经取得了一些重要进展。发现的海藻肽类化合物并确定其化学结构式的主要有二肽、环肽和脂肽,这些肽类化合物具有抗肿瘤、降血压、降血脂、抗凝血、促进神经细胞分化、抗氧化、抗菌和抗病毒等生物活性。预测海藻肽类化合物在疑难病症的治疗上将发挥重要作用。     

抗癌肽的作用机制研究进展

近年来癌症的发生率和死亡率呈现逐渐上升的趋势,是威胁人类生命的主要疾病之一。抗癌肽(Anticancer peptides,ACPs)即具有抗肿瘤活性的生物活性肽,其广泛存在于多种生物体内,包括哺乳动物、两栖类动物、昆虫、植物和微生物等。抗癌肽在治疗肿瘤方面具有众多优势,如分子量低、结构简单、高抗癌活性、高选择性、较少的副作用、多种给药方式、不易引起多重耐药性等。文中结合本课题组相关工作,归纳了目前所发现的抗癌肽的作用机制,以期为新型肽类抗肿瘤药物的研发提供一定的方向。     

海绵生理活性物质研究新进展

本文综述了近三年来从海绵中得到的萜类、生物碱、甾醇、肽类等具有抗菌、抗病毒、抗肿瘤、抗爱滋病及心血管活性等生理活性的物质。     

两个改造后的肿瘤抑素抗肿瘤活性肽活性研究

为了研究改造后的肿瘤抑素2个抗肿瘤活性肽的作用机制,明确其不同的抗肿瘤活性,采用基因工程技术原理,人工合成肿瘤抑素中185～203位氨基酸所对应的19肽和T7肽(74～98位氨基酸)基础上改造的21肽碱基序列,将其与融合蛋白表达载体pTYB2重组后转化到大肠杆菌BL21(DE3)中进行诱导表达,用几丁质亲和层析柱一步纯化,直接获得19肽和21肽,利用MTT法、细胞生长曲线、TUNEL法、流式细胞仪早期细胞凋亡检测和细胞周期检测,小鼠H22腹水型转移型肝癌实体瘤抑瘤实验并结合组织病理学切片,来研究19肽和21肽单独应用或联合应用对肿瘤细胞和内皮细胞生长和凋亡的影响以及对体内肿瘤的抑制情况.体内外实验表明:获得的19肽抗肿瘤活性以直接作用肿瘤细胞为主,也有抑制新生血管生成的作用.基因重组21肽抗肿瘤作用是通过抑制肿瘤组织新生血管生成实现的.19肽、21肽联合应用对肿瘤细胞、内皮细胞生长抑制和促凋亡作用明显增强,抗肿瘤活性大大提高.联合用药弥补了单独用药不足,产生协同抗肿瘤作用,可能会成为今后肿瘤治疗的一个主要方向.     

肿瘤抑素抗肿瘤相关肽的克隆及生物活性

为得到肿瘤抑素中具有直接抗肿瘤活性肽并检测其生物学活性,人工合成肿瘤抑素中185～2 0 3位氨基酸(19肽)所对应的核苷酸序列,将其连接到融合蛋白表达载体pTYB2中,酶切和测序鉴定后,转化到大肠杆菌BL 2 1(DE3)中诱导表达.表达的融合蛋白经几丁质亲和层析、二硫苏糖醇(DTT)的柱内还原,直接获得可溶性19肽.利用MTT法,细胞生长曲线,小鼠H2 2腹水型转移型肝癌实体瘤模型抑瘤实验并结合组织病理学切片,研究19肽的生物学活性.获得的19肽对B16小鼠黑色素瘤细胞、人SMMC 772 1肝癌细胞、人脐静脉内皮细胞的生长均具有抑制作用.小鼠H2 2腹水型肝癌抑瘤率达4 8 4 6 % .病理学切片显示,19肽可促使小鼠肿瘤组织坏死,血管数量减少.19肽具有较强的直接抗肿瘤活性,有可能成为肿瘤治疗的一种新的有前景的药物.     

替加环素在肿瘤治疗领域的研究进展

替加环素(Tigecycline)作为一种新型甘氨环素类抗菌药物,其不仅具有抗生素的功能,还具有潜在的抗肿瘤活性。文中对替加环素单独用药、联合用药及其作用机理进行了系统的综述,并进一步阐释了其作为一种线粒体DNA翻译抑制剂,主要通过抑制线粒体蛋白合成和诱发线粒体的功能障碍,进而影响肿瘤细胞的增殖、迁移和侵袭等进程。虽然替加环素单药治疗肿瘤还存在许多争议,但其联合用药的优势还是十分明显的。因此,还需要更多的研究来深度地挖掘替加环素潜在的抗肿瘤活性,争取使其尽早用于肿瘤的临床治疗,有望成为一种廉价高效的抗肿瘤新药物。     

人内皮抑素抗肿瘤相关肽基因的克隆表达及活性研究

目的 克隆并表达人内皮抑素抗肿瘤相关肽,检测其生物活性。方法 人工合成人内皮抑素1—30位氨基酸（30肽,序列25—31由RGIRGAD改为RGDRGD）所对应的核苷酸序列,连接到质粒pTYB2中,再转化至大肠埃希菌BL21（DE3）中表达,几丁质亲和层析树脂一步纯化30肽。通过MTT法、鸡胚绒毛尿囊膜（CAM）实验、小鼠体内抑瘤实验比较30肽和内皮抑素抗肿瘤活性。结果 MTT证实30肽体外对人脐静脉内皮细胞（HUVEC）、胃癌7901细胞（SGC-7901）半数抑制浓度IC50为36μg／ml、47μg／nl,显著低于内皮抑素IC50179μg／ml、202μg／ml。CAM实验中30肽对血管的抑制作用更强。30肽在小鼠体内抑瘤率47．8％,效果优于内皮抑素28．7％。结论 30肽具有更强抗肿瘤活性,有可能成为治疗肿瘤的一种新药物。     

谷氨酰胺活性肽营养液对大鼠小肠营养作用的研究

用氨甲蝶呤诱发小肠炎后 ,SD大鼠分别饲喂Gln含量不等的氨基酸营养液 ,结果表明 ,72h内 ,第一组 (零剂量组 )大鼠的死亡率为 6 6 .7% ,第二组 (含Gln质量分数 2 % )为 16 .7% ,第三组 (活性肽组 ,含Gln质量分数 2 0 % )和第四组 (结晶氨基酸液 ,含Gln质量分数 2 0 % )为 0 ,并且第三组和第四组的体重、蔗糖酶活、氨肽酶活、DNA和RNA的含量增加 ,说明Gln活性肽营养液对小肠具有明显的营养作用。     

免疫活性地龙肽的制备及其对小鼠巨噬细胞活性的影响

分离纯化免疫活性地龙肽并研究其对小鼠巨噬细胞活性的影响.通过抽提、离心、超滤及色谱等步骤提取小分子量免疫活性地龙肽;通过体外实验测定其对巨噬细胞吞噬活性的影响.结果表明,一定浓度的3种免疫活性地龙肽在体外均可明显增强小鼠巨噬细胞的吞噬活性,提示其具有免疫调节功能.     

The effects of shortening lactoferrin derived peptides against tumour cells, bacteria and normal human cells.

A number of shortened derivatives of the lactoferrin model peptide L12, PAWRKAFRWAKRMLKKAA, were designed in order to elucidate the structural basis for antitumour activity of lactoferrin derivatives. Three tumour cell lines were included in the study and toxicity determined by measuring lysis of human red blood cells and fibroblasts. The results demonstrated a strong correlation between antitumour activity and net positive charge, in which a net charge close to +7 was essential for a high antitumour activity. In order to increase the antitumour activity of the shortest peptide with a net charge less than +7, the hydrophobicity had to be increased by adding a bulky Trp residue. None of the peptides were haemolytic, but toxicity against fibroblasts was observed. However, modifications of the peptides had a higher effect on reducing fibroblast toxicity than antitumour activity and thereby resulted in peptides displaying an almost 7-fold selectivity for tumour cells compared with fibroblasts. The antimicrobial activity against the Gram-negative bacteria Escherichia coil and the Gram-positive bacteria Staphylococcus aureus was also included in order to compare the structural requirements for antitumour activity with those required for a high antimicrobial activity. The results showed that most of the peptides were highly active against both bacterial strains. Less modification by shortening the peptide sequences was tolerated for maintaining a high antitumour activity and selectivity compared with antimicrobial activity. The order of the amino acid residues and thereby the conformation of the peptides was highly essential for antitumour activity, whereas the antimicrobial activity was hardly influenced by changes in this parameter. Thus, in addition to a certain net positive charge and hydrophobicity, the ability to adopt an amphipathic conformation was a more critical structural parameter for antitumour activity than for antimicrobial activity, and implied that a higher flexibility or number of active conformations was tolerated for the peptides to exert a high antimicrobial activity.     

Designing improved active peptides for therapeutic approaches against infectious diseases

Infectious diseases are one of the main causes of human morbidity and mortality. In the last few decades, pathogenic microorganisms' resistance to conventional drugs has been increasing, and it is now pinpointed as a major worldwide health concern. The need to search for new therapeutic options, as well as improved treatment outcomes, has therefore increased significantly, with biologically active peptides representing a new alternative. A substantial research effort is being dedicated towards their development, especially due to improved biocompatibility and target selectivity. However, the inherent limitations of peptide drugs are restricting their application. In this review, we summarize the current status of peptide drug development, focusing on antiviral and antimicrobial peptide activities, highlighting the design improvements needed, and those already being used, to overcome the drawbacks of the therapeutic application of biologically active peptides.     

A review of fish-derived antioxidant and antimicrobial peptides: their production, assessment, and applications

Fishes are rich sources of structurally diverse bioactive compounds. In recent years, much attention has been paid to the existence of peptides with biological activities and proteins derived from foods that might have beneficial effects for humans. Antioxidant and antimicrobial peptides isolated from fish sources may be used as functional ingredients in food formulations to promote consumer health and improve the shelf life of food products. This paper presents an overview of the antioxidant and antimicrobial peptides derived from various fishes. In addition, we discuss the extraction of fish proteins, enzymatic production, and the techniques used to isolate and characterize these compounds. Furthermore, we review the methods used to assay the bioactivities and their applications in food and nutraceuticals.     

Cyclotides: a natural combinatorial peptide library or a bioactive sequence player?

Abstract

In this perspective review, we focalized our attention on the application of cyclotides in drug discovery. To date, two principal approaches have been explored since now: (i) the use of cyclotides as scaffold in which bioactive peptides can be grafted to improve stability, oral bioactivity and binding to GPCRs; (ii) their application as natural peptides library. For these reasons, cyclotides probably represent today a step further in the development of new tools in drug design.     

Artificial peptides to induce membrane denaturation and disruption and modulate membrane composition and fusion

Membranes consisting of phospholipid bilayers are an essential constituent of eukaryotic cells and their compartments. The alteration of their composition, structure, and morphology plays an important role in modulating physiological processes, such as transport of molecules, cell migration, or signaling, but it can also lead to lethal effects. The three main classes of membrane-active peptides that are responsible for inducing such alterations are cell-penetrating peptides (CPPs), antimicrobial peptides (AMPs), and fusion peptides (FPs). These peptides are able to interact with lipid bilayers in highly specific and tightly regulated manners. They can either penetrate the membrane, inducing nondestructive, transient alterations, or disrupt, permeabilize, or translocate through it, or induce membrane fusion by generating attractive forces between two bilayers. Because of these properties, membrane-active peptides have attracted the attention of the pharmaceutical industry, and naturally occurring bioactive structures have been used as a platform for synthetic modification and the development of artificial analogs with optimized therapeutic properties to transport biologically active cargos or serve as novel antimicrobial agents. In this review, we focus on synthetic membrane interacting peptides with bioactivity comparable with their natural counterparts and describe their mechanism of action.     

Antitumoral cyclic peptide analogues of chlamydocin

A series of cyclic tetrapeptides bearing the bioactive alkylating group on an ε-amino-lysyl function have been examined for their antitumoral activity on L1210 and P388 murine leukemia cell lines. One analogue belonging to the chlamydocin family and bearing a β-chloroethylnitrosourea group was found to be potent at inhibiting L1210 cell proliferation and had a higher therapeutic index than the reference compound bis-β-chloroethylnitrosourea (BCNU) on the in vivo P388-induced leukemia model.     

蛙类皮肤分泌物中的抗菌肽和抗癌肽

蛙类的皮肤分泌物中包括了种类繁多,功能复杂的生理活性物质。本文从抗菌肽的杀菌机理出发,综述了蛙类的皮肤分泌物近几年的最新研究进展,重点介绍了抗菌肽结构和功能的关系,。并报告了抗癌肽的最新研究进展以及蛙类活性肽在临床上的应用前景。     

Antimicrobial peptides: key components of the innate immune system

Life-threatening infectious diseases are on their way to cause a worldwide crisis, as treating them effectively is becoming increasingly difficult due to the emergence of antibiotic resistant strains. Antimicrobial peptides (AMPs) form an ancient type of innate immunity found universally in all living organisms, providing a principal first-line of defense against the invading pathogens. The unique diverse function and architecture of AMPs has attracted considerable attention by scientists, both in terms of understanding the basic biology of the innate immune system, and as a tool in the design of molecular templates for new anti-infective drugs. AMPs are gene-encoded short (<100 amino acids), amphipathic molecules with hydrophobic and cationic amino acids arranged spatially, which exhibit broad spectrum antimicrobial activity. AMPs have been the subject of natural evolution, as have the microbes, for hundreds of millions of years. Despite this long history of co-evolution, AMPs have not lost their ability to kill or inhibit the microbes totally, nor have the microbes learnt to avoid the lethal punch of AMPs. AMPs therefore have potential to provide an important breakthrough and form the basis for a new class of antibiotics. In this review, we would like to give an overview of cationic antimicrobial peptides, origin, structure, functions, and mode of action of AMPs, which are highly expressed and found in humans, as well as a brief discussion about widely abundant, well characterized AMPs in mammals, in addition to pharmaceutical aspects and the additional functions of AMPs.     

Artificial cationic peptides that increase nuclease resistance of siRNA without disturbing RNAi activity

Properties of cationic peptides bearing amino or guanidino groups with various side chain lengths that bind to double stranded RNAs (dsRNAs) were investigated. Peptides with shorter side chain lengths effectively bound to dsRNAs (12mers) increasing their thermal stability. NMR measurements suggested that the cationic peptide binds to the inner side of the major groove of dsRNA. These peptides also increased the thermal stability of siRNA and effectively protected from RNase A digestion. On the other hand, both peptides containing amino groups and guanidine groups did not disturb RNAi activity.     

Parallel evaluation of antimicrobial peptides derived from the synthetic PAF26 and the human LL37

The antimicrobial hexapeptide PAF26 was de novo designed towards phytopathogenic fungi of agricultural importance. To analyze its clinical potential, the activity of PAF26 has been determined against several microorganisms of clinical relevance including Staphylococcus, Candida, and several dermatophytes. For comparison purposes, the peptides KR20 and KI26 derived from the human cathelicidin LL37 were selected and fungal pathogens of agronomic relevance were included. PAF26 has similar antimicrobial activity in vitro compared to KR20 despite their different lengths and amino acid compositions. Moreover, neither peptide is lytic to human erythrocytes or keratinocytes. The hybrid peptide PAF26:KR20 showed better antimicrobial properties than the original peptides against most of the pathogens tested. The structural properties of PAF26:KR20 compared to related 26-amino acid peptides support the idea that the increment in toxicity correlates with positive charge and hydrophobicity. However, the degree of peptide helicity was not a predictor of antimicrobial activity.