Antimicrobial Peptides - 자연과학
ANTIMICROBIALPEPTIDES
Antimicrobial PeptidesANTIMICROBIALPEPTIDESOFFEREDBY BACHEMRibosomally synthesized antimicrobial peptides (AMPs) constitute astructurally diverse group of molecules found virtually in all organisms.Most antimicrobial peptides contain less than 100 amino acid residues,have a net positive charge, and are membrane active. They are majorplayers in the innate immune defense but can also have roles in processes as chemokine induction, chemotaxis, inflammation, and woundhealing. In addition to their antimicrobial effects, many of them showantiviral and antineoplastic activities.2
INTRODUCTIONAMPs are a heterogeneous group of relatively small molecules usually containingless than a hundred amino acids. They werefirst described in the 1960’s by Zeya andSpitznagel in polymorphonuclear leukocytelysosomes.To date, more than 1700 AMPs have beenidentified and registered in databases(e.g. http://aps.unmc.edu/AP/main.php).They are produced by nearly all groups oforganisms, including bacteria, fungi, plants,and animals. Many vertebrate AMPs aresecreted by epithelial surfaces such as thetracheal, lingual, or intestinal mucosa ofmammals or the skin of amphibia. Some areexpressed in neutrophils, monocytes, andmacrophages.AMPs are involved in both animal and plantimmune defense systems. Constitutivelyexpressed or induced they play a key role inthe first line of defense against microbialintruders.Structure/ClassificationAMPs can be classified on the basis of theiramino acid composition and structure. Twomajor groups of AMPs can be distinguished.The first group consists of linear moleculeswhich either tend to adopt α-helical structure or are enriched in certain amino acidssuch as arginine, glycine, histidine, proline,and tryptophan. The second group consistsof cysteine-containing peptides which canbe divided into single or multiple disulfidestructures. In many cases, the presence ofdisulfide bridges is required for antimicrobial activity.Most AMPs are cationic peptides, but thereare also anionic peptides such as dermcidin, an aspartic acid-rich peptide fromhuman and maximin H5 from amphibianskin. Other non-cationic AMPs includefragments from neuropeptide precursor molecules such as proenkephalin A,aromatic dipeptides primarily isolated fromdipteran larvae, or peptides derived fromoxygen-binding proteins from arthropod orannelid species.Mode of ActionMost AMPs act by provoking an increase inplasma membrane permeability. They preferentially target microbial versus mammalian cells. Selectivity is influenced by severalfactors such as differences in membranecomposition: membranes of many bacterial pathogens contain negatively chargedlipid moieties such as phosphatidylglycerol(PG), cardiolipin, and phosphatidylserine(PS), whereas mammalian membranes,commonly enriched in phosphatidylethanolamine (PE), phosphatidylcholine (PC)and sphingomyelin, are generally neutral innet charge. The presence of sterols such ascholesterol and ergesterol within the membrane may be a further means by whichAMPs can distinguish between mammalianor fungal cells and prokaryotes.A first step in the mechanism of membrane permeabilization is the electrostaticinteraction between the positively chargedAMP with the negatively charged membranesurface of the microorganism. Subsequentdisruption of the membrane by creation ofpores within the microbial membrane ultimately results in cell death of the organismdue to leakage of ions, metabolites, cessation of membrane-coupled respiration,and biosynthesis. Several models for poreformation such as the Barrel-Stave, theToroidal or Wormhole Model, and the CarpetModel have been proposed (Fig. 1).3
Antimicrobial PeptidesThe Barrel-Stave ModelThe Barrel-Stave model describes amechanism in which AMPs form a barrellike pore within the bacterial membranewith the individual AMPs or AMP complexesbeing the staves. Arranged in this manner,the hydrophobic regions of the AMPs pointoutwards towards the acyl chains of themembrane whereas the hydrophilic areasform the pore.other example for changing the surface netcharge is the production of cationic lysinesubstituted phosphatidylglycerol (L-PG)found in certain Staphylococcus aureusstrains. In Gram-negative bacteria, addition of 4-aminoarabinose (Ara4N) to thephosphate group of the lipid A backbone orincreased acylation of lipopolysaccharides(LPS) are important mechanisms of AMPresistance.MOST AMPs ACT BY PROVOKINGAN INCREASE IN PLASMAMEMBRANE PERMEABILITYThe Toroidal Pore or Wormhole ModelThe pores described by this model differ from those of the Barrel-Stave model.Primarily, the outer and inner leaflet of themembrane are not intercalated in the transmembrane channel.The Carpet ModelA different mechanism is proposed in theCarpet model where AMPs first cover theouter surface of the membrane and thendisrupt the membrane like detergents byforming micelle-like units.Certain AMPs penetrate the bacterialmembrane without channel formation. Theyact on intracellular targets by e.g. inhibitingnucleic acid and/or protein synthesis.ResistanceResistance to AMPs can either be constitutive or inducible. Inherited resistancemechanisms include altered surfacecharge, active efflux, production of peptidases or trapping proteins, and modification of host cellular processes. For instance,Staphylococcus aureus manages to reducethe overall cell surface charge by esterification of the cell wall component teichoicacid with D-alanine and thereby increasesits resistance against human AMPs. An-4Exposure to AMPs may also induce stressresponses by which microorganisms try tosurvive. Inducible regulatory mechanismshave been described in a variety of organisms. For instance, the PhoP/PhoQ regulonin Salmonella has been demonstrated toregulate transcriptional activation of surface and secretory proteins, enzymes thatmodify lipopolysaccharide, lipid and proteinconstituents of the outer membrane andproteases that likely degrade certain AMPs.ABCFig. 1.Mode of ActionA Barrel-Stave ModelB Toroidal Pore orWormhole ModelC Carpet Model
ExamplesLinear cationic α-helical peptidesAndropin from insectsBombinin from amphibiansBuforin II from amphibiansCAP18 from rabbitsCepropins from insectsCecropin P1 from the pig intestinal parasitic nematode,Ascaris suumCeratotoxin from insectsDermaseptin from amphibiansLL-37 from humanMagainin from amphibiansMellitin from insectsPleurocidin from Pseudopleuronectes americanusCationic peptides enriched for specificamino acidsGlycine-containing peptidesHymenoptaecin from honeybeesGlycine- and proline-containing peptidesColeoptericin from beetlesHolotricin from beetlesHistidine-containing peptidesHistatins from humans and some higher primatesProline-containing peptidesAbaecin from honeybeesProline- and arginine-containing peptidesApidaecins from honeybeesBactenicins from cattleDrosocin from DrosophilaPR-39 from pigsProline- and phenylalanine-containing peptides Prophenin from pigsTryptophan-containing peptidesIndolicidin from cattleAnionic and cationic peptides that containcysteine and form disulfide bonds1 Disulfide bondBrevinins2 Disulfide bondsProtegrins from pigs3 Disulfide bondsα-Defensins from human, rabbits and ratsβ-Defensins from humans, cattle, mice, rats, pigs, goatsand poultryθ-Defensin from the rhesus monkeyInsect defensins (Defensin-A from Aedes aegypti)4 Disulfide bondsAntifungal defensins from plantsDrosomycin from DrosophilaAnionic peptidesDermcidin from human skinMaximin H5 from amphibian skinAnionic and cationic peptide fragmentsderived from precursor proteinsAntimicrobial domains from bovine α-lactalbumin, human hemoglobin, lysozyme, and ovalbuminAromatic dipeptides from dipteran larvaeCasocidin I from human caseinEnkelytin from proenkaphalin ALactoferricin from lactoferrinadapted from K.A. Brogden, Nat. Rev. Microbiol. 3, 238-250 (2005)5
Antimicrobial PeptidesIMPORTANT FAMILIESOF AMPsBombininsBombinins constitute a family of AMPsproduced in fire-bellied toads (Bombinaspecies) active against Gram-negative andGram-positive bacteria and fungi. Bombinins, bombinin-like peptides (BLPs), andBombinin H molecules are found in thespecies Bombina bombina, Bombina variegata, and Bombina orientalis, whereas thehomologous maximins and maximin H peptides are derived from the giant fire-belliedtoad Bombina maxima.Bombinin H peptides contain either 17or 20 amino acid residues and are morehydrophobic than bombinins, some of themcontain D-alloisoleucine at position 2. Theyexhibit lower antibacterial activity thanbombinins but, in contrast to them, theypossess haemolytic activity.CathelicidinsMembers of this family are amphipathic,cationic peptides with a broad-spectrumantimicrobial activity. Cathelicidins typicallyact by disrupting the integrity of bacterialmembranes. They are characterized by anevolutionary conserved N-terminal cathelin-like domain of approximately 99-114amino acid residues linked to a C-terminalantimicrobial domain of 12-100 residuesthat can be released upon proteolytic processing.Members of this family include linearpeptides amongst them a number ofproline-rich AMPs that show differenttypes of proline repeat motifs (Bac5, Bac7,PR-39, prophenins) and the tryptophan-richindolicidin characterized by three regularlyspaced proline residues.The protegrins (PG-1 to PG-5) contain two disulfide bridges and an amidated C-terminus.Cathelicidins have been found in everymammalian species examined. In human,LL-37 (Product H-7298) is the only member of the cathelicidin family. The peptideconsists of 37 amino acids and contains6two leucine residues at the N-terminus. Itis proteolytically cleaved from the 18 kDaprecursor protein human cathelicidin antimicrobial protein CAP-18. LL-37 is primarilyproduced by phagocytic leucocytes andepithelial cells, and is involved in variousprocesses such as direct killing of microorganisms, binding and neutralizing LPS, chemotaxis and chemokine induction, regulation of inflammatory responses, and woundhealing. Its production is influenced byseveral factors such as microbial products,host cytokines, vitamin D3, and availabilityof oxygen.LL-37 orthologues in mouse and rat areCRAMP (mouse) (Product H-6526) andCRAMP (rat), respectively.CecropinsCecropins were first isolated from the giantsilk moth Hyalophora cecropia. They canform amphipathic, α-helical structures andare structurally related to other cecropinsas bactericidin, lepidopteran, and sarcotoxin. Cecropin P1 (Product H-5718), foundin pig intestine, also belongs to this family.Most cecropins show broad-spectrumantibacterial activity. Cecropin A (ProductH-3094) and B (Product H-3096) have alsobeen demonstrated to possess tumoricidalactivity against mammalian leukemia, lymphoma, and carcinoma cell lines.CeratotoxinsThis family consists of cationic α-helicalamphipathic peptides expressed in thefemale reproductive accessory glands of theMediterranean fruit fly Ceratitis capitata.The production of the peptides is enhancedby mating.Ceratotoxin A (Product H-1616) and ceratotoxin B (Product H-1618) are 29 aminoacid peptides differing in two amino acids.Ceratotoxin C and D consist of 32 and 36amino acids, respectively.The peptides of this family are active
against Gram-negative as well as Grampositive bacteria and are supposed to actvia the Barrel-Stave model. Ceratotoxin Ahas been shown to be mainly antibacterialfor Gram-negative organisms.DefensinsDefensins are small cysteine-rich cationicpeptides containing three or four disulfidebridges. They have been isolated from molluscs, acari, arachnids, insects, mammals,and plants. They are further divided intofamilies on the basis of the spatial distribution of their cysteine residues.Three families, the α-, β- and θ-defensins,can be distinguished in mammals. α- andβ-defensins are characterized by antiparallel β-sheet structures stabilized by three disulfide bonds. The θ-defensins are found inrhesus monkey and some other non-humanprimates but not in human, chimpanzee andgorilla. They consist of two nine amino acidpeptides derived from different precursorproteins joined by head-to-tail cyclization.Invertebrate and plant defensins containthree or four disulfide bridges, respectively.Insect and mammalian defensins are mainlyactive against bacteria while most plantdefensins possess antifungal activity.DermaseptinsThe peptides of the dermaseptin family areclosely related and consist of 28-34 aminoacids. They were originally isolated fromskin extracts of the South American arboreal frog Phyllomedusa sauvagei and containa conserved tryptophan residue at position3. Dermaseptins exhibit broad-spectrumantimicrobial activity against Gram-positiveand Gram-negative bacteria.HistatinsHistatins are histidine-rich and mostly cationic peptides found in the saliva of humansand some higher primates. They are activeagainst a broad-spectrum of bacteria andfungi.The antifungal activity of the human salivarypeptide histatin-5 (Product H-3144) hasbeen extensively studied and is supposed tobe due to inhibition of mitochondrial respiration and the formation of reactive oxygenspecies. Histatin-5 has also been shownto inhibit both host-derived and bacterialproteolytc enzymes involved in peridontaldiseases.Histatin-8 (Product H-1422), a peptide fromhuman parotid secretion, has been shown toinhibit hemagglutination activity of Porphyromonas gingivalis 381, a Gram-negativebacterium involved in certain forms of periodontal disease. The peptide may functionas a binding domain for the hemagglutininsof Porphyromonas gingivalis during agglutination.MagaininsMagainins constitute a family of linearamphipathic cationic AMPs discovered inthe skin of Xenopus laevis. The two closelyrelated members of this family, magainin I(Product H-6565) and magainin II(Product H-6570) differ merely in two positions and are 23 amino acids in length.Magainins exhibit broad-spectrum antimicrobial activity against Gram-negative andGram-positive bacteria, fungi and protozoaand are also cytotoxic for many murine andhuman cancer cell lines.CONCLUSIONSThe structures of AMPs represent a uniquesource for the targeted exploration of newapplications in the therapy of microbial andviral infection, cancer, and sepsis. Modernsynthetic methods will allow the relativelycheap and accurate production of leadcompounds and peptide candidates. Theachievements in peptide library generation,analytical methods as mass spectrometry,and screening and formulation technologiesmay contribute to solve intrinsic problems associated with the use of AMPs astherapeutic agents such as susceptibility toproteases and host toxicity.Bachem has considerable expertise andlong-standing experience in peptide synthesis. With our capacity to upscale the production of simple and modified peptides, we arethe partner of choice for the pharmaceuticalindustries.7
Antimicrobial PeptidesREFERENCESE. Martin et al.Defensins and other endogenouspeptide antibiotics of vertebrates.J. Leukoc. Biol. 58, 128-136 (1995)ReviewD. Andreu and L. RivasAnimal antimicrobial peptides: anoverview.Biopolymers 47, 415-433 (1998)ReviewR.E. Hancock and R. LehrerCationic peptides: a new source ofantibiotics.Trends Biotechnol. 16, 82-88 (1998)ReviewR.E. Hancock and D.S. ChapplePeptide antibiotics.Antimicrob. Agents Chemother. 43,1317-1323 (1999) ReviewM. ZasloffAntimicrobial peptides of multicellular organisms.Nature 415, 389-395 (2002)D.A. DevineAntimicrobial peptides in defence ofthe oral and respiratory tracts.Mol. Immunol. 40, 431-443 (2003)ReviewA.E. Shinnar et al.Cathelicidin family of antimicrobialpeptides: proteolytic processing andprotease resistance.Bioorg. Chem. 31, 425-436 (2003)ReviewM.R. Yeaman and N.Y. YountMechanisms of antimicrobial peptide action and resistance.Pharmacol. Rev. 55, 27-55 (2003)ReviewT. Jin et al.Staphylococcus aureus resistshuman defensins by production ofstaphylokinase, a novel bacterialevasion mechanism.J. Immunol. 172, 1169-1176 (2004)8M.E. SelstedTheta-defensins: cyclic antimicrobial peptides produced by binary ligation of truncated alpha-defensins.Curr. Protein Pept. Sci. 5, 365-371(2004) ReviewM. ZanettiCathelicidins, multifunctional peptides of the innate immunity.J. Leukoc. Biol. 75, 39-48 (2004)ReviewK.A. BrogdenAntimicrobial peptides: pore formersor metabolic inhibitors in bacteria?Nat. Rev. Microbiol. 3, 238-250 (2005)ReviewM. ZanettiThe role of cathelicidins in the innate host defenses of mammals.Curr. Issues Mol. Biol. 7, 179-196(2005) ReviewR.E. Hancock and H.G. SahlAntimicrobial and host-defensepeptides as new anti-infectivetherapeutic strategies.Nat. Biotechnol. 24, 1551-1557(2006) ReviewH. Jenssen et al.Peptide antimicrobial agents.Clin. Microbiol. Rev. 19, 491-511(2006) ReviewV. NizetAntimicrobial peptide resistancemechanisms of human bacterialpathogens.Curr. Issues Mol. Biol. 8, 11-26 (2006)ReviewM. GolecCathelicidin LL-37: LPS-neutralizing,pleiotropic peptide.Ann. Agric. Environ. Med. 14, 1-4(2007) ReviewM.L. Mangoni et al.Biological characterization andmodes of action of temporins andbombinins H, multiple forms of shortand mildly cationic anti-microbialpeptides from amphibian skin.J. Pept. Sci. 13, 603-613 (2007)ReviewD.W. Hoskin and A. RamamoorthyStudies on anticancer activities ofantimicrobial peptides.Biochim. Biophys. Acta 1778, 357375 (2008) ReviewJ. Schauber and R.L. GalloAntimicrobial peptides and the skinimmune defense system.J. Allergy Clin. Immunol. 122, 261-266(2008) ReviewH. Suttmann et al.Antimicrobial peptides of the cecropin-family show potent anti-tumoractivity against bladder cancer cells.BMC Urol. 8, 5 (2008)K. Yamasaki and R.L. GalloAntimicrobial peptides in humanskin disease.Eur. J. Dermatol. 18, 11-21 (2008)ReviewG. Diamond et al.The roles of antimicrobial peptidesin innate host defense.Curr. Pharm. Des. 15, 2377-2392(2009) ReviewY. Lai and R.L. GalloAMPed up immunity: how antimicrobial peptides have multiple roles inimmune defense.Trends Immunol. 30, 131-141 (2009)ReviewA. Nijnik and R.E. HancockThe roles of cathelicidin LL-37 inimmune defences and novel clinicalapplications.Curr. Opin. Hematol. 16, 41-47 (2009)Review
M. OttoBacterial sensing of antimicrobialpeptides.Contrib. Microbiol. 16, 136-149(2009) ReviewP.C. Oyston et al.Novel peptide therapeutics for treatment of infections.J. Med. Microbiol. 58, 977-987 (2009)ReviewR. Palffy et al.On the physiology and pathophysiology of antimicrobial peptides.Mol. Med. 15, 51-59 (2009) ReviewM. Simmaco et al.Bombinins, antimicrobial peptidesfrom Bombina species.Biochim. Biophys. Acta 1788, 15511555 (2009) ReviewC.L. StevensonAdvances in peptide pharmaceuticals.Curr. Pharm. Biotechnol. 10, 122-137(2009) ReviewA. Zairi et al.Dermaseptins and magainins:antimicrobial peptides from frogs’skin-new sources for a promisingspermicides microbicides-a minireview.J. Biomed. Biotechnol. 2009, 452567(2009) ReviewP. Mendez-SamperioThe human cathelicidin hCAP18/LL-37: a multifunctional peptideinvolved in mycobacterial infections.Peptides 31, 1791-1798 (2010)ReviewJ. Wiesner and A. VilcinskasAntimicrobial peptides: the ancientarm of the human immune system.Virulence 1, 440-464 (2010) Review9
Antimicrobial PeptidesANTIMICROBIALPEPTIDESAntimicrobial peptides are produced by plants and most organismsthroughout the animal kingdom including humans. AMPs protectagainst a broad range of infectious agents, as bacteria, fungi, andviruses.10
CATHELINRELATED ANTIMICROBIAL (CRAMP)PEPTIDESCATHEPSIN GPEPTIDESCECROPINSCRAMP MP-18 (mouse)H-6528GEKLKKIGQKIKNFFQKLCathepsin G (77-83)H-1266HPQYNQRCecropin cropin opin A (1-7)-Melittin A (2-9) amideH-5948KWKLFKKIGAVLKVL-NH2Cecropin P1H-5718SWLSKTAKKLENSAKKRISEGIAIAIQGGPRCecropin A (1-8)-Melittin (1-18) INSCeratotoxin AH-1616SIGSALKKALPVAKKIGKIALPIAKAALPCeratotoxin BH-1618SIGSAFKKALPVAKKIGKAALPIAKAALP11
Antimicrobial PeptidesDEFENSINSCorticostatin I isulfide bonds between Cys3 andCys31/Cys5 and Cys20/Cys10 and Cys30)α-Defensin 6H-6566AFTCHCRRSCYSTEYSYGTCTVMGINHRFCCL(Disulfide bonds between Cys4 andCys31/Cys6 and Cys20/Cys10 and Cys30)Defensin HNP-1 ��de bonds between Cys2 andCys31/Cys4 and Cys19/Cys9 and Cys29)Defensin HNP-3 ��de bonds between Cys2 andCys30/Cys4 and Cys19/Cys9 and Cys29)rec β-Defensin 1 (human)H-5584rec β-Defensin 2 (human)H-5586Retrocyclin-1 (RC-100)H-6126c(GICRCICGRGICRCICGR)(Disulfide bonds between Cys3 andCys16/Cys5 and Cys14/Cys7 and Cys12)Defensin HNP-2 �de bonds between Cys1 andCys29/Cys3 and Cys18/Cys8 and Cys28)HEPCIDINSHepcidin-20 (human)H-7358ICIFCCGCCHRSKCGMCCKT(Disulfide bonds, air oxidized)Hepcidin-25 (human)H-5926DTHFPICIFCCGCCHRSKCGMCCKT(Disulfide bonds between Cys7 andCys23/Cys10 and Cys13/Cys14 and HHSHRGYBiotinyl-Hepcidin-25 sulfide bonds between Cys7 andCys23/Cys10 and Cys13/Cys14 and Cys22)Histatin-8H-1422KFHEKHHSHRGY
KERATINOCYTESKIN CELLS,LIGHT MICROGRAPHKeratinocyte skin cells, fluorescentlight micrograph.Fluorescent dyes have been used tohighlight tissues, cellular structuresand proteins: f-actin (green), cell nuclei(pink), defensins (yellow and red). Actinis a protein that is a major part of a cell’scytoskeleton, and one of its forms isfilamentous actin (f-actin). Defensinsare proteins that help defend againstpathogenic bacteria, fungi and viruses,and are commonly found in epithelialcells such as skin cells. Keratinocytesare the major type of skin cell, changing as they pass through the skin andeventually becoming dead keratinisedcells at the skin’s surface.KEYSTONE/SCIENCE PHOTO LIBRARY/R. BICK, B. POINDEXTER, UT MEDICALSCHOOL13
Antimicrobial VPRTESBiotinyl-LL-37 LVPRTES-NH2LL-37 H2KR-12 (human)H-6688KRIVQRIKDFLR-NH2MAGAININSMagainin IH-6565GIGKFLHSAGKFGKAFVGEIMKSMagainin IIH-6570GIGKFLHSAKKFGKAFVGEIMNSMELITTINSCecropin A (1-7)-Melittin A (2-9) KVLTTGLPALISWIKRKRQQ-NH2LL-37 ANDFRAGMENTSCecropin A (1-8)-Melittin (1-18) PTIDES ANDANALOGSTUFTSIN TuftsinH-5025TK(Z)PR
MISCELLANEOUSAcetyl-Adhesin (1025-1044) r Death lfide nin-Like Peptide (BLP-1)H-8625GIGASILSAGKSALKGLAKGLAEHFANNH2Parasin PAMICAVTKKC(Disulfide lfide KAVCVCRN(Disulfide bonds between Cys3 andCys30/Cys16 and Cys36/Cys20 and TISQGTQSeminalplasmin Fragment (SPF)AnalogH-1636PKLLKTFLSKWIGDermcidin-1L HDVKDVLDSVLTachyplesin IH-1202KWCFRVCYRGICYRRCR-NH2(Disulfide bonds between Cys3 andCys16/Cys7 and ritrpticinH-3908VRRFPWWWPFLRR15
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Antimicrobial Peptides 2 ANTIMICROBIAL PEPTIDES OFFERED BY BACHEM Ribosomally synthesized antimicrobial peptides (AMPs) constitute a structurally diverse group of molecules found virtually in all organisms. Most antimicrobial peptides contain less than 100 amino acid residues, have a net positive charge, and are membrane active. They are major
Antimicrobials, Aspergillus fumigatus, Antimicrobial Peptides 1. Introduction 1.1. Antimicrobial Peptides and Proteins It is notable that antimicrobial peptides particularly cationic ones play a signifi-cant role within the natural immunity of animal defences against topical and general microbes altogether species of life. These antimicrobial .
-Helical Antimicrobial Peptides. Approximately to % of all antimicrobial peptides identi ed and studied to date contain predominant -helical structures. is may be due the relative ease with which these peptides are chemically synthesised, which allows for extensive charac-terisation in the laboratory. e se peptides usually consist
Several groups in the 1970s and 1980s reported antimicrobial peptides produced from leukocytes, including α-defensins from rabbits and humans [10]. One important landmark in the history of antimicrobial peptides is the work of Boman et al. in 1981. Boman injected bacteria into pupae of a silk moth and isolated the antimicrobial peptides
Plant antimicrobial peptides Plants are constantly exposed to attack from a large range of pathogens. Under attack conditions plants synthesized antimicrobial peptides as innate defence. Thionins were the first antimicrobial peptides to be isolated from plants, and normally consists of 45-48 amino acids.
and charge requirements for the interaction of endogenous antimicrobial peptides and short peptides that have been derived from them, with membranes. ß 1999 Elsevier Science B.V. . tion of antimicrobial peptides with biological and model membranes in relation to the biological activ-ities that have emerged from extensive investigations
Antimicrobial peptides Antimicrobial peptides (AMPs) are oligopeptides with a varying number (from five to over a hundred) of amino acids AMPs have a broad spectrum of targeted organisms ranging from viruses, bacteria, fungi to parasites Historically AMPs have also been referred to as cationic host defense peptides, anionic antimicrobial peptides/
activity mechanisms, and their antimicrobial activity against a broad spectrum of microorganisms, such as gram-positive and gram-negative bacteria as well as fungi, parasites and viruses (23-25 ). 1.2. Antimicrobial peptides - a new class of antibi otics? Antimicrobial peptides are part of the innate immune system and play an important
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