Biomedical subjects

Yechiel Shai

Publications and source records attributed to Yechiel Shai.

At least 19 recordsLinked to original sources

PubMed2007

Impairment of innate immune killing mechanisms by bacteriostatic antibiotics.

Antibiotics are designed to support host defense in controlling infection. Here we describe a paradoxical inhibitory effect of bacteriostatic antibiotics on key mediators of mammalian innate immunity. When growth of species including Escherichia coli and Staphylococcus aureus is suppressed by chloramphenicol or erythromycin, the susceptibility of the bacteria to cathelicidin antimicrobial peptides or serum complement was markedly diminished. Survival of the bacteria in human whole blood, human wound fluid, or a mouse wound infection model was in turn increased after antibiotic-induced bacteriostasis. These findings provide a further rationale against the indiscriminate use of antibiotics.

Animals↗

PubMed2006

T-cell inactivation and immunosuppressive activity induced by HIV gp41 via novel interacting motif.

Fusion peptide (FP) of the HIV gp41 molecule inserts into the T cell membrane during virus-cell fusion. FP also blocks the TCR/CD3 interaction needed for antigen-triggered T cell activation. Here we used in vitro (fluorescence and immunoprecipitation), in vivo (T cell mediated autoimmune disease adjuvant arthritis), and in silico methods to identify the FP-TCR novel interaction motif: the alpha-helical transmembrane domain (TMD) of the TCR alpha chain, and the beta-sheet 5-13 region of the 16 N-terminal aa of FP (FP(1-16)). Deciphering the molecular mechanism of the immunosuppressive activity of FP provides a new potential target to overcome the immunosuppressant activity of HIV, and in addition a tool for down-regulating immune mediated inflammation.

Amino Acid Sequence↗

PubMed2006

Ultrashort antibacterial and antifungal lipopeptides.

Host-defense cationic antimicrobial peptides ( approximately 12-50 aa long) play an essential protective role in the innate immune system of all organisms. Lipopeptides, however, are produced only in bacteria and fungi during cultivation, and they are composed of specific lipophilic moieties attached to anionic peptides (six to seven amino acids). Here we report the following. (i) The attachment of an aliphatic chain to otherwise inert, cationic D,L tetrapeptides endows them with potent activity against various microorganisms including antibiotic resistance strains. (ii) Cell specificity is determined by the sequence of the short peptidic chain and the length of the aliphatic moiety. (iii) Despite the fact that the peptidic chains are very short, their mode of action involves permeation and disintegration of membranes, similar to that of many long antimicrobial peptides. Besides adding important information on the parameters necessary for host-defense lipopeptides to kill microorganisms, the simple composition of these lipopeptides and their diverse specificities should make them economically available, innate immunity-mimicking antimicrobial and antifungal compounds for various applications.

Amino Acid Sequence↗

PubMed2006

Functional and structural characterization of HIV-1 gp41 ectodomain regions in phospholipid membranes suggests that the fusion-active conformation is extended.

HIV-1 entry into its host cell involves a sequential interaction whereby gp41 is in direct contact with the plasma membrane. Understanding the effect of membrane composition on the fusion mechanism can shed light on the unsolved phases of this complex mechanism. Here, we studied N36, a peptide derived from the N-heptad-repeat (NHR) of the gp41 ectodomain, its six helix bundle (SHB) forming counterpart C34, together with the N-terminal 70-mer wild-type peptide (N70), and additional gp41 ectodomain-derived peptides in the presence of two membranes, modeling inner and outer leaflets of the plasma membrane. Information on the structure of these peptides, their affinity towards phospholipids and their ability to induce vesicle fusion was gathered by a variety of fluorescence, spectroscopic and microscopy methods. We found that N36, having strong affinity towards phospholipids, prominently shifts conformation from alpha-helix in an outer leaflet-like zwitterionic membrane to beta-sheet in a membrane mimicking the negatively charged inner leaflet environment, leading to pronounced fusion-activity. Real-time atomic force microscopy (AFM) was used to study the peptides' effect on the membrane morphology, revealing severe bilayer perturbation and extensive pore formation. We also found, that the N36/C34 core is destabilized by electronegative, but not zwitterionic phospholipids. Taken together, our data suggest that the fusion-active pore forming conformation of gp41 is extended, upstream of the SHB. In this manner, folding of the ectodomain into a SHB might also serve as a negative regulator of fusion by impeding gp41 fusion-active surfaces, thus preventing irreversible damage to the cell membrane. This assumption is supported by the finding that pre-incubation of large unilamellar vesicles (LUV) with C-heptad repeat (CHR)-derived fusion inhibitors reduces the fusogenic activity of N-terminal peptides in a dose-dependant manner, and suggests that CHR-derived fusion inhibitors inhibit HIV entry in an analogous mechanism.

Cell Membrane↗

PubMed2006

A synergism between temporins toward Gram-negative bacteria overcomes resistance imposed by the lipopolysaccharide protective layer.

Temporins are short and homologous antimicrobial peptides (AMPs) isolated from the frog skin of Rana genus. To date, very little is known about the biological significance of the presence of closely related AMPs in single living organisms. Here we addressed this question using temporins A, B, and L isolated from Rana temporaria. We found that temporins A and B are only weakly active toward Gram-negative bacteria. However, a marked synergism occurs when each is mixed with temporin L. To shed light on the underlying mechanisms involved in these activities, we used various experimental strategies to investigate: (i) the effect of the peptides' interaction on both the viability and membrane permeability of intact bacteria and spheroplasts; (ii) their interaction with lipopolysaccharides (LPS) and the effect of LPS on the oligomeric state of temporins, alone or combining one with another; (iii) their structure in solution and when bound to LPS, by using circular dichroism and ATR-FTIR spectroscopies. Our data reveal that temporin L synergizes with A and B by preventing their oligomerization in LPS. This should promote their translocation across the outer membrane into the cytoplasmic membrane. To the best of our knowledge, this is the first study that explains how a combination of native AMPs from the same species can overcome bacterial resistance imposed by the LPS leaflet.

Amphibian Proteins↗

PubMed2006

Lipopolysaccharide (Endotoxin)-host defense antibacterial peptides interactions: role in bacterial resistance and prevention of sepsis.

Lipopolysaccharide (LPS) is the major molecular component of the outer membrane of Gram-negative bacteria and serves as a physical barrier providing the bacteria protection from its surroundings. LPS is also recognized by the immune system as a marker for the detection of bacterial pathogen invasion, responsible for the development of inflammatory response, and in extreme cases to endotoxic shock. Because of these functions, the interaction of LPS with LPS binding molecules attracts great attention. One example of such molecules are antimicrobial peptides (AMPs). These are large repertoire of gene-encoded peptides produced by living organisms of all types, which serve as part of the innate immunity protecting them from pathogen invasion. AMPs are known to interact with LPS with high affinities. The biophysical properties of AMPs and their mode of interaction with LPS determine their biological function, susceptibility of bacteria to them, as well as the ability of LPS to activate the immune system. This review will discuss recent studies on the molecular mechanisms underlying these interactions, their effects on the resistance of the bacteria to AMPs, as well as their potential to neutralize LPS-induced endotoxic shock.

Anti-Infective Agents↗

PubMed2006

Characterization of the HIV N-terminal fusion peptide-containing region in context of key gp41 fusion conformations.

Central to our understanding of human immunodeficiency virus-induced fusion is the high resolution structure of fragments of the gp41 fusion protein folded in a low energy core conformation. However, regions fundamental to fusion, like the fusion peptide (FP), have yet to be characterized in the context of the cognate protein regardless of its conformation. Based on conformation-specific monoclonal antibody recognition, we identified the polar region consecutive to the N36 fragment as a stabilizer of trimeric coiled-coil assembly, thereby enhancing inhibitory potency. This tertiary organization is retained in the context of the hydrophobic FP (N70 fragment). Our data indicate that the N70 fragment recapitulates the expected organization of this region in the viral fusion intermediate (N-terminal half of the pre-hairpin intermediate (N-PHI)), which happens to be the prime target for fusion inhibitors. Regarding the low energy conformation, we show for the first time core formation in the context of the FP (N70 core). The alpha-helical and coiled-coil stabilizing polar region confers substantial thermal stability to the core, whereas the hydrophobic FP does not add further stability. For the two key fusion conformations, N-PHI and N70 core, we find that the FP adopts a nonhelical structure and directs higher order assembly (assembly of coiled coils in N-PHI and assembly of bundles in the N70 core). This supra-molecular organization of coiled coils or folded cores is seen only in the context of the FP. This study is the first to characterize the FP region in the context of the folded core and provides a basic understanding of the role of the elusive FP for key gp41 fusion conformations.

Antibodies, Monoclonal↗

PubMed2006

Inhibition of tumor growth and elimination of multiple metastases in human prostate and breast xenografts by systemic inoculation of a host defense-like lytic peptide.

We report on a short host defense-like peptide that targets and arrests the growth of aggressive and hormone-resistant primary human prostate and breast tumors and prevents their experimental and spontaneous metastases, respectively, when systemically inoculated to immunodeficient mice. These effects are correlated with increased necrosis of the tumor cells and a significant decrease in the overall tumor microvessel density, as well as newly formed capillary tubes and prostate-specific antigen secretion (in prostate tumors). Growth inhibition of orthotopic tumors derived from stably transfected highly fluorescent human breast cancer cells and prevention of their naturally occurring metastases were visualized in real time by using noninvasive whole-body optical imaging. The exclusive selectivity of the peptide towards cancer derives from its specific binding to surface phosphatidylserine and the killing of the cancer cells via cytoplasmic membrane depolarization. These data indicate that membrane disruption can provide a therapeutic means of inhibiting tumor growth and preventing metastases of various cancers.

Adenocarcinoma↗

PubMed2006

Effect of natural L- to D-amino acid conversion on the organization, membrane binding, and biological function of the antimicrobial peptides bombinins H.

Antimicrobial peptides (AMPs) are evolutionarily old components of innate immunity found in all living pluricellular organisms. Interestingly, some organisms express families of AMPs with only a slight variation among their members, possibly to increase their spectrum of activity. Despite the growing body of knowledge about their biological activity and mode of action on bacteria, only a few of them have been tested on Leishmania, a worldwide spread protozoan pathogen, and the parameters contributing to this activity are yet to be determined. We report on the anti-Leishmania activity and mode of action of bombinins H2 and H4 isolated from the skin secretion of the frog Bombina variegata. H4, the most active, is the first natural AMP of animal origin with a single L- to D-amino acid isomerization. Membrane depolarization and membrane permeation assays, as well as electron microscopy, suggest that the lethal mechanism involves plasma membrane permeation and/or disruption. To better understand the enhanced activity of H4, we determined the peptide's structure in membranes mimicking those of mammals, bacteria, and Leishmania by using ATR-FTIR and CD spectroscopies and assessed their membrane binding by using surface plasmon resonance. The data reveal that (i) H2 but not H4 partially aggregates in membranes mimicking those of Leishmania, (ii) H2 is slightly more helical than H4 in all membranes, and (iii) H4 binds the Leishmania model membrane approximately 5-fold better than H2. This study highlights the importance of a single alpha-amino acid epimerization as a tool used by nature to modulate the activity of AMPs. In addition, our findings suggest bombinins H as potential templates for the development of new drugs with a new mode of action against Leishmania.

Animals↗

PubMed2006

Structurally altered peptides reveal an important role for N-terminal heptad repeat binding and stability in the inhibitory action of HIV-1 peptide DP178.

Human immunodeficiency virus 1 gp41 folds into a six-helix bundle whereby three C-terminal heptad repeat regions pack in an anti-parallel manner against the coiled-coil formed by three N-terminal heptad repeats (NHR). Peptides that inhibit bundle formation contributed significantly to the understanding of the entry mechanism of the virus. DP178, which partially overlaps C-terminal heptad repeats, prevents bundle formation through an undefined mechanism; additionally it has been suggested to bind other ENV regions and arrest fusion in an unknown manner. We used two structurally altered DP178 peptides; in each, two sequential amino acids were substituted into their d configuration, d-SQ in the hydrophilic N-terminal region and d-LW in the hydrophobic C-terminal. Importantly, we generated an elongated NHR peptide, N54, obtaining the full N-helix docking site for DP178. Interestingly, d-LW retained wild type fusion inhibitory activity, whereas d-SQ exhibited significantly reduced activity. In correlation with the inhibitory data, CD spectroscopy and fluorescence studies revealed that all the DP178 peptides interact with N54, albeit with different stabilities of the bundles. We conclude that strong binding of DP178 N-terminal region to the endogenous NHR, without significant contribution of the C-terminal sequence of DP178 to core formation, is vital for DP178 inhibition. The finding that d-amino acid incorporation in the C terminus did not affect activity or membrane binding as revealed by surface plasmon resonance correlates with an additional membrane binding site, or membrane anchoring role, for the C terminus, which works synergistically with the N terminus to inhibit fusion.

Amino Acid Sequence↗

PubMed2006

Host defense peptides and lipopeptides: modes of action and potential candidates for the treatment of bacterial and fungal infections.

Endogenous peptide antibiotics (termed also host-defense or antimicrobial peptides) are known as evolutionarily old components of innate immunity. They were found initially in invertebrates, but later on also in vertebrates, including humans. This secondary, chemical immune system provides organisms with a repertoire of small peptides that act against invasion (for both offensive and defensive purposes) by occasional and obligate pathogens. Each antimicrobial peptide has a broad but not identical spectrum of antimicrobial activity, predominantly against bacteria, providing the host maximum coverage against a rather broad spectrum of microbial organisms. Many of these peptides interact with the target cell membranes and increase their permeability, which results in cell lysis. A second important family includes lipopeptides. They are produced in bacteria and fungi during cultivation on various carbon sources, and possess a strong antifungal activity. Unfortunately, native lipopeptides are non-cell selective and therefore extremely toxic to mammalian cells. Whereas extensive studies have emerged on the requirements for a peptide to be antibacterial, very little is known concerning the parameters that contribute to antifungal activity. This review summarizes recent studies aimed to understand how antimicrobial peptides and lipopeptides select their target cell. This includes a new group of lipopeptides highly potent against pathogenic fungi and yeast. They are composed of inert cationic peptides conjugated to aliphatic acids with different lengths. Deep understanding of the molecular mechanisms underlying the differential cells specificity of these families of host defense molecule is required to meet the challenges imposed by the life-threatening infections.

Bacterial Infections↗

PubMed2005

Endotoxin (lipopolysaccharide) neutralization by innate immunity host-defense peptides. Peptide properties and plausible modes of action.

Binding of lipopolysaccharide (LPS) to macrophages results in proinflammatory cytokine secretion. In extreme cases it leads to endotoxic shock. A few innate immunity antimicrobial peptides (AMPs) neutralize LPS activity. However, the underlying mechanism and properties of the peptides are not yet clear. Toward meeting this goal we investigated four AMPs and their fluorescently labeled analogs. These AMPs varied in composition, length, structure, and selectivity toward cells. The list included human LL-37 (37-mer), magainin (24-mer), a 15-mer amphipathic alpha-helix, and its D,L-amino acid structurally altered analog. The peptides were investigated for their ability to inhibit LPS-mediated cytokine release from RAW264.7 and bone marrow-derived primary macrophages, to bind LPS in solution, and when LPS is already bound to macrophages (fluorescence spectroscopy and confocal microscopy), to compete with LPS for its binding site on the CD14 receptor (flow cytometry) and affect LPS oligomerization. We conclude that a strong binding of a peptide to LPS aggregates accompanied by aggregate dissociation prevents LPS from binding to the carrier protein lipopolysaccharide-binding protein, or alternatively to its receptor, and hence inhibits cytokine secretion.

Amino Acid Sequence↗

PubMed2005

Utilizing ESEEM spectroscopy to locate the position of specific regions of membrane-active peptides within model membranes.

Membrane-active peptides participate in many cellular processes, and therefore knowledge of their mode of interaction with phospholipids is essential for understanding their biological function. Here we present a new methodology based on electron spin-echo envelope modulation to probe, at a relatively high resolution, the location of membrane-bound lytic peptides and to study their effect on the water concentration profile of the membrane. As a first example, we determined the location of the N-terminus of two membrane-active amphipathic peptides, the 26-mer bee venom melittin and a de novo designed 15-mer D,L-amino acid amphipathic peptide (5D-L9K6C), both of which are antimicrobial and bind and act similarly on negatively charged membranes. A nitroxide spin label was introduced to the N-terminus of the peptides and measurements were performed either in H2O solutions with deuterated model membranes or in D2O solutions with nondeuterated model membranes. The lipids used were dipalmitoyl phosphatidylcholine (DPPC) and phosphatidylglycerol (PG), (DPPC/PG (7:3 w/w)), egg phosphatidylcholine (PC) and PG (PC/PG (7:3 w/w)), and phosphatidylethanolamine (PE) and PG (PE/PG, 7:3w/w). The modulation induced by the 2H nuclei was determined and compared with a series of controls that produced a reference "ruler". Actual estimated distances were obtained from a quantitative analysis of the modulation depth based on a simple model of an electron spin situated at a certain distance from the bottom of a layer with homogeneously distributed deuterium nuclei. The N-terminus of both peptides was found to be in the solvent layer in both the DPPC/PG and PC/PG membranes. For PE/PG, a further displacement into the solvent was observed. The addition of the peptides was found to change the water distribution in the membrane, making it "flatter" and increasing the penetration depth into the hydrophobic region.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed2005

Mechanistic and functional studies of the interaction of a proline-rich antimicrobial peptide with mammalian cells.

Mammalian antimicrobial peptides provide rapid defense against infection by inactivating pathogens and by influencing the functions of cells involved in defense responses. Although the direct antibacterial properties of these peptides have been widely characterized, their multiple effects on host cells are only beginning to surface. Here we investigated the mechanistic and functional aspects of the interaction of the proline-rich antimicrobial peptide Bac7(1-35) with mammalian cells, as compared with a truncated analog, Bac7(5-35), lacking four critical N-terminal residues (RRIR) of the Bac7(1-35) sequence. By using confocal microscopy and flow cytometry, we showed that although the truncated analog Bac7(5-35) remains on the cell surface, Bac7(1-35) is rapidly taken up into 3T3 and U937 cells through a nontoxic energy- and temperature-dependent process. Cell biology-based assays using selective endocytosis inhibitors and spectroscopic and surface plasmon resonance studies of the interaction of Bac7(1-35) with phosphatidylcholine/cholesterol model membranes collectively suggest the concurrent contribution of macropinocytosis and direct membrane translocation. Structural studies with model membranes indicated that membrane-bound Bac7(5-35) is significantly more aggregated than Bac7(1-35) due to the absence of the N-terminal cationic cluster, thus providing an explanation for hampered cellular internalization of the truncated form. Further investigations aimed to reveal functional implications of intracellular uptake of Bac7(1-35) demonstrated that it correlates with enhanced S phase entry of 3T3 cells, indicating a novel function for this proline-rich peptide.

Animals↗

PubMed2005

Conjugation of fatty acids with different lengths modulates the antibacterial and antifungal activity of a cationic biologically inactive peptide.

Many studies have shown that an amphipathic structure and a threshold of hydrophobicity of the peptidic chain are crucial for the biological function of AMPs (antimicrobial peptides). However, the factors that dictate their cell selectivity are not yet clear. In the present study, we show that the attachment of aliphatic acids with different lengths (10, 12, 14 or 16 carbon atoms) to the N-terminus of a biologically inactive cationic peptide is sufficient to endow the resulting lipopeptides with lytic activity against different cells. Mode-of-action studies were performed with model phospholipid membranes mimicking those of bacterial, mammalian and fungal cells. These include determination of the structure in solution and membranes by using CD and ATR-FTIR (attenuated total reflectance Fourier-transform infrared) spectroscopy, membrane leakage experiments and by visualizing bacterial and fungal damage via transmission electron microscopy. The results obtained reveal that: (i) the short lipopeptides (10 and 12 carbons atoms) are non-haemolytic, active towards both bacteria and fungi and monomeric in solution. (ii) The long lipopeptides (14 and 16 carbons atoms) are highly antifungal, haemolytic only at concentrations above their MIC (minimal inhibitory concentration) values and aggregate in solution. (iii) All the lipopeptides adopt a partial alpha-helical structure in 1% lysophosphatidylcholine and bacterial and mammalian model membranes. However, the two short lipopeptides contain a significant fraction of random coil in fungal membranes, in agreement with their reduced antifungal activity. (iv) All the lipopeptides have a membranolytic effect on all types of cells assayed. Overall, the results reveal that the length of the aliphatic chain is sufficient to control the pathogen specificity of the lipopeptides, most probably by controlling both the overall hydrophobicity and the oligomeric state of the lipopeptides in solution. Besides providing us with basic important information, these new lipopeptides are potential candidates that can target bacteria and/or fungi, especially in cases where the bacterial flora should not be harmed.

Amino Acid Sequence↗

PubMed2005

Controlled alteration of the shape and conformational stability of alpha-helical cell-lytic peptides: effect on mode of action and cell specificity.

A novel method, based on the rational and systematic modulation of macroscopic structural characteristics on a template originating from a large number of natural, cell-lytic, amphipathic alpha-helical peptides, was used to probe how the depths and shapes of hydrophobic and polar faces and the conformational stability affect antimicrobial activity and selectivity with respect to eukaryotic cells. A plausible mode of action explaining the peptides' behaviour in model membranes, bacteria and host cells is proposed. Cytotoxic activity, in general, correlated strongly with the hydrophobic sector depth, and required a majority of aliphatic residue side chains having more than two carbon atoms. It also correlated significantly with the size of polar sector residues, which determines the penetration depth of the peptide via the so-called snorkel effect. Both an oblique gradient of long to short aliphatic residues along the hydrophobic face and a stabilized helical structure increased activity against host cells but not against bacteria, as revealed by haemolysis, flow cytofluorimetric studies on lymphocytes and surface plasmon resonance studies with model phosphatidylcholine/cholesterol membranes. The mode of interaction changes radically for a peptide with a stable, preformed helical conformation compared with others that form a structure only on membrane binding. The close correlation between effects observed in biological and model systems suggests that the 'carpet model' correctly represents the type of peptides that are bacteria-selective, whereas the behaviour of those that lyse host cells is more complex.

Amino Acid Sequence↗

PubMed2005

The HIV fusion peptide adopts intermolecular parallel beta-sheet structure in membranes when stabilized by the adjacent N-terminal heptad repeat: a 13C FTIR study.

The HIV gp41 protein mediates fusion with target host cells. The region primarily involved in directing fusion, the fusion peptide (FP), is poorly understood at the level of structure and function due to its toxic effect in expression systems. To overcome this, we used a synthetic approach to generate the N70 construct, whereby the FP is stabilized in context of the adjacent auto oligomerization domain. The amide I profile of unlabeled N70 in membranes reveals prominent alpha-helical contribution, along with significant beta-structure. By truncating the N terminus (FP region) of N70, beta-structure is eliminated, suggesting that the FP adopts a beta-structure in membranes. To assess this directly, (13)C Fourier-transformed infra-red analysis was carried out to map secondary structure of the 16 N-terminal hydrophobic residues of the fusion peptide (FP16). The (13)C isotope shifted absorbance of the FP was filtered from the global secondary structure of the 70 residue construct (N70). On the basis of the peak shift induced by the (13)C-labeled residues of FP16, we directly assign beta-sheet structure in ordered membranes. A differential labeling scheme in FP16 allows us to distinguish the type of beta-sheet structure as parallel. Dilution of each FP16-labeled N70 peptide, by mixing with unlabeled N70, shows directly that the FP16 beta-strand region self-assembles. We discuss our structural findings in the context of the prevailing gp41 fusion paradigm. Specifically, we address the role of the FP region in organizing supramolecular gp41 assembly, and we also discuss the mechanism by which exogenous, free FP constructs inhibit gp41-induced fusion.

Amino Acid Sequence↗

PubMed2005

pH-dependent antifungal lipopeptides and their plausible mode of action.

Antimicrobial peptides and lipopeptides play an essential protective role in the innate immune system of all organisms. Despite many studies, the factors that dictate their cell-selectivity and pH-dependent activity are yet not clear. This is important because various organs of the human body have an acidic pH environment, for example, the vagina, gastric lumen, cryogenic dental foci, and lung-lining fluids in cystic fibrosis and asthma. In this study we synthesized a new group of lipopeptides by conjugating dodecanoic acid (DDA) to the N-termini of 12-mer peptides LXXLLXXLLXXL (L(6)X(6), X = Lys, His, Arg, and all the leucines are d-amino acid enantiomers) and investigated their pH-dependent biological activity and a plausible mode of action by using model phospholipids mimicking bacterial, mammalian, and fungal membranes. The data revealed that, depending on the basic amino acid incorporated, the lipopeptides are active against both bacteria and fungi or solely toward fungi. Furthermore, their activity is expressed at an acidic pH alone, neutral pH alone, or at both environments. Determination of secondary structure, membrane leakage experiments, surface plasmon resonance (SPR) binding experiments, and transmission electron microscopy suggest the involvement of a membranolytic effect. This mode of action, which should make it hard for the microorganism to develop resistance, their selective and pH-dependent activity, as well as pharmacological advantages due to the presence of d-amino acids, make them potential candidates for the treatment of mycoses in organs, under various pH environments, especially in cases where the bacterial flora should not be harmed.

Amino Acid Sequence↗