Journal articles: 'Cationic Amphiphilic Peptides'

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Silva Nigenda, Ezequiel, Tobias M. Postma, Mohammed Hezwani, Alin Pirvan, Susan Gannon, Carol-Anne Smith, Mathis Riehle, and Rob M. J. Liskamp. "Synthesis and cellular penetration properties of new phosphonium based cationic amphiphilic peptides." MedChemComm 9, no. 6 (2018): 982–87. http://dx.doi.org/10.1039/c8md00113h.

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Akkarawongsa, Radeekorn, Terra B. Potocky, Emily P. English, Samuel H. Gellman, and Curtis R. Brandt. "Inhibition of Herpes Simplex Virus Type 1 Infection by Cationic β-Peptides." Antimicrobial Agents and Chemotherapy 52, no. 6 (April 7, 2008): 2120–29. http://dx.doi.org/10.1128/aac.01424-07.

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ABSTRACT Previously, it was shown that cationic α-peptides derived from the human immunodeficiency virus TAT protein transduction domain blocked herpes simplex virus type 1 (HSV-1) entry. We now show that cationic oligomers of β-amino acids (“β-peptides”) inhibit HSV-1 infection. Among three cationic β-peptides tested, the most effective inhibition was observed for the one with a strong propensity to adopt a helical conformation in which cationic and hydrophobic residues are segregated from one another (“globally amphiphilic helix”). The antiviral effect was not cell type specific. Inhibition of virus infection by the β-peptides occurred at the postattachment penetration step, with a 50% effective concentration of 3 μM for the most-effective β-peptide. The β-peptides did not inactivate virions in solution, nor did they induce resistance to infection when cells were pretreated with the β-peptides. The β-peptides showed little if any toxicity toward Vero cells. These results raise the possibility that cationic β-peptides may be useful antiviral agents for HSV-1 and demonstrate the potential of β-peptides as novel antiviral drugs.

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Schweizer, Frank. "Cationic amphiphilic peptides with cancer-selective toxicity." European Journal of Pharmacology 625, no. 1-3 (December 2009): 190–94. http://dx.doi.org/10.1016/j.ejphar.2009.08.043.

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Findlay, Brandon, George G. Zhanel, and Frank Schweizer. "Cationic Amphiphiles, a New Generation of Antimicrobials Inspired by the Natural Antimicrobial Peptide Scaffold." Antimicrobial Agents and Chemotherapy 54, no. 10 (August 9, 2010): 4049–58. http://dx.doi.org/10.1128/aac.00530-10.

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ABSTRACT Naturally occurring cationic antimicrobial peptides (AMPs) and their mimics form a diverse class of antibacterial agents currently validated in preclinical and clinical settings for the treatment of infections caused by antimicrobial-resistant bacteria. Numerous studies with linear, cyclic, and diastereomeric AMPs have strongly supported the hypothesis that their physicochemical properties, rather than any specific amino acid sequence, are responsible for their microbiological activities. It is generally believed that the amphiphilic topology is essential for insertion into and disruption of the cytoplasmic membrane. In particular, the ability to rapidly kill bacteria and the relative difficulty with which bacteria develop resistance make AMPs and their mimics attractive targets for drug development. However, the therapeutic use of naturally occurring AMPs is hampered by the high manufacturing costs, poor pharmacokinetic properties, and low bacteriological efficacy in animal models. In order to overcome these problems, a variety of novel and structurally diverse cationic amphiphiles that mimic the amphiphilic topology of AMPs have recently appeared. Many of these compounds exhibit superior pharmacokinetic properties and reduced in vitro toxicity while retaining potent antibacterial activity against resistant and nonresistant bacteria. In summary, cationic amphiphiles promise to provide a new and rich source of diverse antibacterial lead structures in the years to come.

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Kaconis, Yani, Ina Kowalski, Jörg Howe, Annemarie Brauser, Walter Richter, Iosu Razquin-Olazarán, Melania Iñigo-Pestaña, et al. "Biophysical Mechanisms of Endotoxin Neutralization by Cationic Amphiphilic Peptides." Biophysical Journal 100, no. 11 (June 2011): 2652–61. http://dx.doi.org/10.1016/j.bpj.2011.04.041.

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Cao, Meiwen, Yuming Wang, Xin Ge, Changhai Cao, Jing Wang, Hai Xu, Daohong Xia, Xiubo Zhao, and Jian R. Lu. "Effects of Anions on Nanostructuring of Cationic Amphiphilic Peptides." Journal of Physical Chemistry B 115, no. 41 (October 20, 2011): 11862–71. http://dx.doi.org/10.1021/jp205987w.

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Wiradharma, Nikken, Ulung Khoe, Charlotte A. E. Hauser, See Voon Seow, Shuguang Zhang, and Yi-Yan Yang. "Synthetic cationic amphiphilic α-helical peptides as antimicrobial agents." Biomaterials 32, no. 8 (March 2011): 2204–12. http://dx.doi.org/10.1016/j.biomaterials.2010.11.054.

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Kundu, Rajen. "Cationic Amphiphilic Peptides: Synthetic Antimicrobial Agents Inspired by Nature." ChemMedChem 15, no. 20 (September 8, 2020): 1887–96. http://dx.doi.org/10.1002/cmdc.202000301.

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Rideout, Darryl C., Michael Lambert, Debra A. Kendall, Gregory R. Moe, David G. Osterman, H. P. Tao, I. Bernard Weinstein, and E. T. Kaiser. "Amphiphilic cationic peptides mediate cell adhesion to plastic surfaces." Journal of Cellular Physiology 124, no. 3 (September 1985): 365–71. http://dx.doi.org/10.1002/jcp.1041240302.

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Strandberg, Erik, Deniz Tiltak, Marco Ieronimo, Nathalie Kanithasen, Parvesh Wadhwani, and Anne S. Ulrich. "Influence of C-terminal amidation on the antimicrobial and hemolytic activities of cationic α-helical peptides." Pure and Applied Chemistry 79, no. 4 (January 1, 2007): 717–28. http://dx.doi.org/10.1351/pac200779040717.

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The effect of C-terminal amidation on the antimicrobial and hemolytic activities of antimicrobial peptides was studied using three cationic peptides which form amphiphilic α-helices when bound to membranes. The natural antimicrobial peptide PGLa, the designer-made antibiotic MSI-103, and the cell-penetrating "model amphipathic peptide" (MAP) are all amidated in their original forms, and their biological activities were compared with the same sequences carrying a free C-terminus. It was found that, in general, a free COOH-terminus reduces both the antimicrobial activity and the hemolytic side effects of the peptides. The only exception was observed for MSI-103, whose antimicrobial activity was not decreased in the acid form. Having shown that the therapeutic index (TI) of this novel peptide is significantly higher than for the other tested peptides, with high antibiotic activity and little undesired effects, we suggest that it could be a useful starting point for further development of new peptide antibiotics.

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Amirkhanov, N. V., N. V. Tikunova, and D. V. Pyshnyi. "Synthetic Antimicrobial Peptides: I. Antimicrobial Activity of Amphiphilic and Nonamphiphilic Cationic Peptides." Russian Journal of Bioorganic Chemistry 44, no. 5 (September 2018): 492–503. http://dx.doi.org/10.1134/s1068162018050035.

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Xiong, Menghua, Michelle W. Lee, Rachael A. Mansbach, Ziyuan Song, Yan Bao, Richard M. Peek, Catherine Yao, et al. "Helical antimicrobial polypeptides with radial amphiphilicity." Proceedings of the National Academy of Sciences 112, no. 43 (October 12, 2015): 13155–60. http://dx.doi.org/10.1073/pnas.1507893112.

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α-Helical antimicrobial peptides (AMPs) generally have facially amphiphilic structures that may lead to undesired peptide interactions with blood proteins and self-aggregation due to exposed hydrophobic surfaces. Here we report the design of a class of cationic, helical homo-polypeptide antimicrobials with a hydrophobic internal helical core and a charged exterior shell, possessing unprecedented radial amphiphilicity. The radially amphiphilic structure enables the polypeptide to bind effectively to the negatively charged bacterial surface and exhibit high antimicrobial activity against both gram-positive and gram-negative bacteria. Moreover, the shielding of the hydrophobic core by the charged exterior shell decreases nonspecific interactions with eukaryotic cells, as evidenced by low hemolytic activity, and protects the polypeptide backbone from proteolytic degradation. The radially amphiphilic polypeptides can also be used as effective adjuvants, allowing improved permeation of commercial antibiotics in bacteria and enhanced antimicrobial activity by one to two orders of magnitude. Designing AMPs bearing this unprecedented, unique radially amphiphilic structure represents an alternative direction of AMP development; radially amphiphilic polypeptides may become a general platform for developing AMPs to treat drug-resistant bacteria.

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Hwang, Peter M., and Hans J. Vogel. "Structure-function relationships of antimicrobial peptides." Biochemistry and Cell Biology 76, no. 2-3 (May 1, 1998): 235–46. http://dx.doi.org/10.1139/o98-026.

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Antimicrobial peptides are ubiquitously produced throughout nature. Many of these relatively short peptides (6-50 residues) are lethal towards bacteria and fungi, yet they display minimal toxicity towards mammalian cells. All of the peptides are highly cationic and hydrophobic. It is widely believed that they act through nonspecific binding to biological membranes, even though the exact nature of these interactions is presently unclear. High-resolution nuclear magnetic resonance (NMR) has contributed greatly to knowledge in this field, providing insight about peptide structure in aqueous solution, in organic cosolvents, and in micellar systems. Solid-state NMR can provide additional information about peptide-membrane binding. Here we review our current knowledge about the structure of antimicrobial peptides. We also discuss studies pertaining to the mechanism of action. Despite the different three-dimensional structural motifs of the various classes, they all have similar amphiphilic surfaces that are well-suited for membrane binding. Many antimicrobial peptides bind in a membrane-parallel orientation, interacting only with one face of the bilayer. This may be sufficient for antimicrobial action. At higher concentrations, peptides and phospholipids translocate to form multimeric transmembrane channels that seem to contribute to the peptide's hemolytic activity. An understanding of the key features of the secondary and tertiary structures of the antimicrobial peptides and their effects on bactericidal and hemolytic activity can aid the rational design of improved analogs for clinical use.Key words: structure, antimicrobial peptide, NMR, membrane, hemolytic.

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Fuchigami, Takeshi, Takeshi Chiga, Sakura Yoshida, Makoto Oba, Yu Fukushima, Hiromi Inoue, Akari Matsuura, Akira Toriba, and Morio Nakayama. "Synthesis and Characterization of Radiogallium-Labeled Cationic Amphiphilic Peptides as Tumor Imaging Agents." Cancers 13, no. 10 (May 14, 2021): 2388. http://dx.doi.org/10.3390/cancers13102388.

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SVS-1 is a cationic amphiphilic peptide (CAP) that exhibits a preferential cytotoxicity towards cancer cells over normal cells. In this study, we developed radiogallium-labeled SVS-1 (67Ga-NOTA-KV6), as well as two SVS-1 derivatives, with the repeating KV residues replaced by RV or HV (67Ga-NOTA-RV6 and 67Ga-NOTA-HV6). All three peptides showed high accumulation in epidermoid carcinoma KB cells (53–143% uptake/mg protein). Though 67Ga-NOTA-RV6 showed the highest uptake among the three CAPs, its uptake in 3T3-L1 fibroblasts was just as high, indicating a low selectivity. In contrast, the uptake of 67Ga-NOTA-KV6 and 67Ga-NOTA-HV6 into 3T3-L1 cells was significantly lower than that in KB cells. An endocytosis inhibition study suggested that the three 67Ga-NOTA-CAPs follow distinct pathways for internalization. In the biodistribution study, the tumor uptakes were found to be 4.46%, 4.76%, and 3.18% injected dose/g of tissue (% ID/g) for 67Ga-NOTA-KV6, 67Ga-NOTA-RV6, and 67Ga-NOTA-HV6, respectively, 30 min after administration. Though the radioactivity of these peptides in tumor tissue decreased gradually, 67Ga-NOTA-KV6, 67Ga-NOTA-RV6, and 67Ga-NOTA-HV6 reached high tumor/blood ratios (7.7, 8.0, and 3.8, respectively) and tumor/muscle ratios (5.0, 3.3, and 4.0, respectively) 120 min after administration. 67Ga-NOTA-HV6 showed a lower tumor uptake than the two other tracers, but it exhibited very low levels of uptake into peripheral organs. Overall, the replacement of lysine in SVS-1 with other basic amino acids significantly influenced its binding and internalization into cancer cells, as well as its in vivo pharmacokinetic profile. The high accessibility of these peptides to tumors and their ability to target the surface membranes of cancer cells make radiolabeled CAPs excellent candidates for use in tumor theranostics.

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Huo, Yehong, Linhao Ma, Mengzhi Zhang, Mingcong Niu, Xiulian Gu, Wenjie Zhang, Miaomiao Yan, and Guangcheng Wei. "Development of anticancer peptides with low hemolysis, high penetrating membrane activity, certain analgesic activity and the synergistic anticancer effect." Biomaterials Science 10, no. 7 (2022): 1724–41. http://dx.doi.org/10.1039/d1bm02024b.

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Amphiphilic cationic anticancer lipopeptide P10 self-assembles into spherical aggregates, which are used as drug carriers to play a synergistic anticancer role, and its anticancer mechanism is presented.

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Wang, Hao, Mingcong Niu, Tong Xue, Linhao Ma, Xiulian Gu, Guangcheng Wei, Fengqiao Li, and Chunhua Wang. "Development of antibacterial peptides with efficient antibacterial activity, low toxicity, high membrane disruptive activity and a synergistic antibacterial effect." Journal of Materials Chemistry B 10, no. 11 (2022): 1858–74. http://dx.doi.org/10.1039/d1tb02852a.

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Amphiphilic cationic antimicrobial lipopeptide LP21 self-assembles into spherical aggregates which are used as drug carriers to play synergistic antibacterial effects and the antibacterial mechanism involved is shown.

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Yosefi, Gal, Ifat Cohen‐Erez, Einat Nativ‐Roth, Hanna Rapaport, and Ronit Bitton. "Spontaneous Alignment of Self‐Assembled Cationic and Amphiphilic β‐Sheet Peptides." Advanced Materials Interfaces 7, no. 14 (June 22, 2020): 2000332. http://dx.doi.org/10.1002/admi.202000332.

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Mandal, Santi M., and Souvik Panda. "Inhaler with electrostatic sterilizer and use of cationic amphiphilic peptides may accelerate recovery from COVID-19." BioTechniques 69, no. 3 (September 2020): 206–10. http://dx.doi.org/10.2144/btn-2020-0042.

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We explore the design of a smart inhaler with electrostatic sterilizer and propose the utilization of cationic amphiphilic peptides, independently or in conjunction with a bronchodilator, for COVID-19 patients to quickly improve wellbeing while maintaining a strategic distance to protect healthcare personnel from virus-containing aerosol or droplets during the process of inhalation.

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Diaferia, Carlo, Elisabetta Rosa, Enrico Gallo, Giovanni Smaldone, Mariano Stornaiuolo, Giancarlo Morelli, and Antonella Accardo. "Self-Supporting Hydrogels Based on Fmoc-Derivatized Cationic Hexapeptides for Potential Biomedical Applications." Biomedicines 9, no. 6 (June 15, 2021): 678. http://dx.doi.org/10.3390/biomedicines9060678.

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Peptide-based hydrogels (PHGs) are biocompatible materials suitable for biological, biomedical, and biotechnological applications, such as drug delivery and diagnostic tools for imaging. Recently, a novel class of synthetic hydrogel-forming amphiphilic cationic peptides (referred to as series K), containing an aliphatic region and a Lys residue, was proposed as a scaffold for bioprinting applications. Here, we report the synthesis of six analogues of the series K, in which the acetyl group at the N-terminus is replaced by aromatic portions, such as the Fmoc protecting group or the Fmoc-FF hydrogelator. The tendency of all peptides to self-assemble and to gel in aqueous solution was investigated using a set of biophysical techniques. The structural characterization pointed out that only the Fmoc-derivatives of series K keep their capability to gel. Among them, Fmoc-K3 hydrogel, which is the more rigid one (G’ = 2526 Pa), acts as potential material for tissue engineering, fully supporting cell adhesion, survival, and duplication. These results describe a gelification process, allowed only by the correct balancing among aggregation forces within the peptide sequences (e.g., van der Waals, hydrogen bonding, and π–π stacking).

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Hadianamrei, Roja, Jiqian Wang, Stephen Brown, and Xiubo Zhao. "Rationally designed cationic amphiphilic peptides for selective gene delivery to cancer cells." International Journal of Pharmaceutics 617 (April 2022): 121619. http://dx.doi.org/10.1016/j.ijpharm.2022.121619.

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Mosca, Simone, Janos Keller, Nahid Azzouz, Stefanie Wagner, Alexander Titz, Peter H. Seeberger, Gerald Brezesinski, and Laura Hartmann. "Amphiphilic Cationic β3R3-Peptides: Membrane Active Peptidomimetics and Their Potential as Antimicrobial Agents." Biomacromolecules 15, no. 5 (April 15, 2014): 1687–95. http://dx.doi.org/10.1021/bm500101w.

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Damen, Mark, Mario Izidoro, Debora Okamoto, Lilian Oliveira, Helene Amatdjais-Groenen, Stijn van Dongen, Koen van Cleef, et al. "Cationic Geminoid Peptide Amphiphiles Inhibit DENV2 Protease, Furin, and Viral Replication." Molecules 27, no. 10 (May 17, 2022): 3217. http://dx.doi.org/10.3390/molecules27103217.

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Dengue is an important arboviral infectious disease for which there is currently no specific cure. We report gemini-like (geminoid) alkylated amphiphilic peptides containing lysines in combination with glycines or alanines (C15H31C(O)-Lys-(Gly or Ala)nLys-NHC16H33, shorthand notation C16-KXnK-C16 with X = A or G, and n = 0–2). The representatives with 1 or 2 Ala inhibit dengue protease and human furin, two serine proteases involved in dengue virus infection that have peptides with cationic amino acids as their preferred substrates, with IC50 values in the lower µM range. The geminoid C16-KAK-C16 combined inhibition of DENV2 protease (IC50 2.3 µM) with efficacy against replication of wildtype DENV2 in LLC-MK2 cells (EC50 4.1 µM) and an absence of toxicity. We conclude that the lysine-based geminoids have activity against dengue virus infection, which is based on their inhibition of the proteases involved in viral replication and are therefore promising leads to further developing antiviral therapeutics, not limited to dengue.

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Bultmann, Hermann, Gary Girdaukas, Glen S. Kwon, and Curtis R. Brandt. "The Virucidal EB Peptide Protects Host Cells from Herpes Simplex Virus Type 1 Infection in the Presence of Serum Albumin and Aggregates Proteins in a Detergent-Like Manner." Antimicrobial Agents and Chemotherapy 54, no. 10 (July 19, 2010): 4275–89. http://dx.doi.org/10.1128/aac.00495-10.

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ABSTRACT The linear cationic amphiphilic EB peptide, derived from the FGF4 signal sequence, was previously shown to be virucidal and to block herpes simplex type I (HSV-1) entry (H. Bultmann, J. S. Busse, and C. R. Brandt, J. Virol. 75:2634–2645, 2001). Here we show that cells treated with EB (RRKKAAVALLPAVLLALLAP) for less than 5 min are also protected from infection with HSV-1. Though protection was lost over a period of 5 to 8 h, it was reinduced as rapidly as during the initial treatment. Below a 20 μM concentration of EB, cells gained protection in a serum-dependent manner, requiring bovine serum albumin (BSA) as a cofactor. Above 40 μM, EB coprecipitated with BSA under hypotonic conditions. Coprecipitates retained antiviral activity and released active peptide. NaCl (≥0.3 M) blocked coprecipitation without interfering with antiviral activity. As shown for β-galactosidase, EB below 20 μM acted as an enzyme inhibitor, whereas above 40 to 100 μM EB, β-galactosidase was precipitated as was BSA or other unrelated proteins. Pyrene fluorescence spectroscopy revealed that in the course of protein aggregation, EB acted like a cationic surfactant and self associated in a process resembling micelle formation. Both antiviral activity and protein aggregation did not depend on stereospecific EB interactions but depended strongly on the sequence of the peptide's hydrophobic tail. EB resembles natural antimicrobial peptides, such as melittin, but when acting in a nonspecific detergent-like manner, it primarily seems to target proteins.

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Hartmann, Mareike, Marina Berditsch, Jacques Hawecker, Mohammad Fotouhi Ardakani, Dagmar Gerthsen, and Anne S. Ulrich. "Damage of the Bacterial Cell Envelope by Antimicrobial Peptides Gramicidin S and PGLa as Revealed by Transmission and Scanning Electron Microscopy." Antimicrobial Agents and Chemotherapy 54, no. 8 (June 7, 2010): 3132–42. http://dx.doi.org/10.1128/aac.00124-10.

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ABSTRACT Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the ultrastructural changes in bacteria induced by antimicrobial peptides (AMPs). Both the β-stranded gramicidin S and the α-helical peptidyl-glycylleucine-carboxyamide (PGLa) are cationic amphiphilic AMPs known to interact with bacterial membranes. One representative Gram-negative strain, Escherichia coli ATCC 25922, and one representative Gram-positive strain, Staphylococcus aureus ATCC 25923, were exposed to the AMPs at sub-MICs and supra-MICs in salt-free medium. SEM revealed a shortening and swelling of the E. coli cells, and multiple blisters and bubbles formed on their surface. The S. aureus cells seemed to burst upon AMP exposure, showing open holes and deep craters in their envelope. TEM revealed the formation of intracellular membranous structures in both strains, which is attributed to a lateral expansion of the lipid membrane upon peptide insertion. Also, some morphological alterations in the DNA region were detected for S. aureus. After E. coli was incubated with AMPs in medium with low ionic strength, the cells appeared highly turgid compared to untreated controls. This observation suggests that the AMPs enhance osmosis through the inner membrane, before they eventually cause excessive leakage of the cellular contents. The adverse effect on the osmoregulatory capacity of the bacteria is attributed to the membrane-permeabilizing action of the amphiphilic peptides, even at low (sub-MIC) AMP concentrations. Altogether, the results demonstrate that both TEM and SEM, as well as appropriate sample preparation protocols, are needed to obtain detailed mechanistic insights into peptide function.

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Park, Jung Woo, Eun-Kyoung Bang, Eun Mi Jeon, and Byeang Hyean Kim. "Complexation and conjugation approaches to evaluate siRNA delivery using cationic, hydrophobic and amphiphilic peptides." Org. Biomol. Chem. 10, no. 1 (2012): 96–102. http://dx.doi.org/10.1039/c1ob06042b.

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Huang, Yuan, Nikken Wiradharma, Kaijin Xu, Zhongkang Ji, Sheng Bi, Lanjuan Li, Yi-Yan Yang, and Weimin Fan. "Cationic amphiphilic alpha-helical peptides for the treatment of carbapenem-resistant Acinetobacter baumannii infection." Biomaterials 33, no. 34 (December 2012): 8841–47. http://dx.doi.org/10.1016/j.biomaterials.2012.08.026.

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Ryder, Matthew P., Xiangming Wu, Greg R. McKelvey, Joseph McGuire, and Karl F. Schilke. "Binding interactions of bacterial lipopolysaccharide and the cationic amphiphilic peptides polymyxin B and WLBU2." Colloids and Surfaces B: Biointerfaces 120 (August 2014): 81–87. http://dx.doi.org/10.1016/j.colsurfb.2014.05.004.

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Dubovskii, P. V., and Y. N. Utkin. "Cobra Cytotoxins: Structural Organization and Antibacterial Activity." Acta Naturae 6, no. 3 (September 15, 2014): 11–18. http://dx.doi.org/10.32607/20758251-2014-6-3-11-18.

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Cardiotoxins (cytotoxins, CT) are -structured proteins isolated from the venom of cobra. They consist of 59-61 amino acid residues, whose antiparallel chains form three fingers. In contrast to neurotoxins with an overall similar fold, CTs are amphiphilic. The amphiphilicity is caused by positively charged lysine and arginine residues flanking the tips of the loops that consist primarily of hydrophobic amino acids. A similar distribution of amino acid residues is typical for linear (without disulfide bonds) cationic cytolytic peptides from the venoms of other snakes and insects. Many of them are now considered to be lead compounds in combatting bacterial infections and cancer. In the present review, we summarize the data on the antibacterial activity of CTs and compare it to the activity of linear peptides.

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Sepahi, Mina, Reza Ahangari Cohan, Shahin Hadadian, and Dariush Norouzian. "Effect of glutamic acid elimination/substitution on the biological activities of S3 cationic amphiphilic peptides." Preparative Biochemistry & Biotechnology 50, no. 7 (June 8, 2020): 664–72. http://dx.doi.org/10.1080/10826068.2020.1725772.

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Li, Yue-Xuan, Yushuang Wei, and Hong-Bo Pang. "Abstract 369: Improving the nanomaterial delivery by using cell-penetrating peptides in the bystander manner." Cancer Research 82, no. 12_Supplement (June 15, 2022): 369. http://dx.doi.org/10.1158/1538-7445.am2022-369.

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Abstract While nanoparticles (NPs) can be useful to improve the diagnosis and treatment of various diseases including cancer, a major limiting factor for their applications is the poor efficiency of cell entry. A common solution to this problem is to covalently link NPs with cell-penetrating peptides (CPPs), such as the transactivator of transcription (TAT) peptide. A few cationic CPPs were previously shown to increase the cellular uptake of co-administered, but not covalently coupled, NP cargo through an endocytic pathway, macropinocytosis. This so-called bystander uptake process is of unique advantage for NP intracellular delivery as it bypasses the requirements of additional chemical modifications. Here, we set out to determine whether other classes of CPPs (e.g. hydrophobic and amphiphilic) exhibit similar bystander activities, and what physico-chemical properties of NPs affect the bystander uptake process. First, we discovered that transportan (TP) peptide, an amphiphilic CPP, can initiate similar bystander uptake process for a variety of NPs and solute tracers. TP-induced bystander uptake relies on macropinocytosis as well, and occurs in a variety of cell types and in physiological tissues. Second, using TAT-functionalized NPs to stimulate the bystander effect, we showed that the bystander activity depends on the size of bystander NPs, with an optimal range around 50 nm in diameter. Compared to rod-like and triangular NPs, spherical NPs showed higher uptake in the bystander manner. Additionally, we investigated how CPP-NPs, once inside cells, get out of one cell and enter another, and found again that NP sizes affect the efficiency of CPP-NP intercellular transport as well. Overall, these efforts lay the foundation to further understand the bystander activity of CPP-assisted cell entry and improve the efficacy of nanomedicine in cancer and other human diseases. Citation Format: Yue-Xuan Li, Yushuang Wei, Hong-Bo Pang. Improving the nanomaterial delivery by using cell-penetrating peptides in the bystander manner [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 369.

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Mousli, Mouaiak, Jean-Luc Bueb, Christian Bronner, Bruno Rouot, and Yves Landry. "G protein activation: a receptor-independent mode of action for cationic amphiphilic neuropeptides and venom peptides." Trends in Pharmacological Sciences 11, no. 9 (September 1990): 358–62. http://dx.doi.org/10.1016/0165-6147(90)90179-c.

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Barba-Bon, Andrea, Giulia Salluce, Irene Lostalé-Seijo, Khaleel I. Assaf, Andreas Hennig, Javier Montenegro, and Werner M. Nau. "Boron clusters as broadband membrane carriers." Nature 603, no. 7902 (March 23, 2022): 637–42. http://dx.doi.org/10.1038/s41586-022-04413-w.

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AbstractThe membrane translocation of hydrophilic substances constitutes a challenge for their application as therapeutic compounds and labelling probes1–4. To remedy this, charged amphiphilic molecules have been classically used as carriers3,5. However, such amphiphilic carriers may cause aggregation and non-specific membrane lysis6,7. Here we show that globular dodecaborate clusters, and prominently B12Br122−, can function as anionic inorganic membrane carriers for a broad range of hydrophilic cargo molecules (with molecular mass of 146–4,500 Da). We show that cationic and neutral peptides, amino acids, neurotransmitters, vitamins, antibiotics and drugs can be carried across liposomal membranes. Mechanistic transport studies reveal that the carrier activity is related to the superchaotropic nature of these cluster anions8–12. We demonstrate that B12Br122− affects cytosolic uptake of different small bioactive molecules, including the antineoplastic monomethyl auristatin F, the proteolysis targeting chimera dBET1 and the phalloidin toxin, which has been successfully delivered in living cells for cytoskeleton labelling. We anticipate the broad and distinct delivery spectrum of our superchaotropic carriers to be the starting point of conceptually distinct cell-biological, neurobiological, physiological and pharmaceutical studies.

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Li, Yue-Xuan, Yushuang Wei, Rui Zhong, Ling Li, and Hong-Bo Pang. "Transportan Peptide Stimulates the Nanomaterial Internalization into Mammalian Cells in the Bystander Manner through Macropinocytosis." Pharmaceutics 13, no. 4 (April 14, 2021): 552. http://dx.doi.org/10.3390/pharmaceutics13040552.

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Covalent coupling with cell-penetrating peptides (CPPs) has been a common strategy to facilitate the cell entry of nanomaterial and other macromolecules. Though efficient, this strategy requires chemical modifications on nanomaterials, which is not always desired for their applications. Recent studies on a few cationic CPPs have revealed that they can stimulate the cellular uptake of nanoparticles (NPs) simply via co-administration (bystander manner), which bypasses the requirement of chemical modification. In this study, we investigated the other classes of CPPs and discovered that transportan (TP) peptide, an amphiphilic CPP, also exhibited such bystander activities. When simply co-administered, TP peptide enabled the cells to engulf a variety of NPs, as well as common solute tracers, while these payloads had little or no ability to enter the cells by themselves. This result was validated in vitro and ex vivo, and TP peptide showed no physical interaction with co-administered NPs (bystander cargo). We further explored the cell entry mechanism for TP peptide and its bystander cargo, and showed that it was mediated by a receptor-dependent macropinocytosis process. Together, our findings improve the understanding of TP-assisted cell entry, and open up a new avenue to apply this peptide for nanomaterial delivery.

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Brunner, Sascha R., Joseph F. A. Varga, and Brian Dixon. "Antimicrobial Peptides of Salmonid Fish: From Form to Function." Biology 9, no. 8 (August 18, 2020): 233. http://dx.doi.org/10.3390/biology9080233.

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Antimicrobial peptides (AMPs) are small, usually cationic, and amphiphilic molecules that play a crucial role in molecular and cellular host defense against pathogens, tissue damage, and infection. AMPs are present in all metazoans and several have been discovered in teleosts. Some teleosts, such as salmonids, have undergone whole genome duplication events and retained a diverse AMP repertoire. Salmonid AMPs have also been shown to possess diverse and potent antibacterial, antiviral, and antiparasitic activity and are induced by a variety of factors, including dietary components and specific molecules also known as pathogen-associated molecular patterns (PAMPs), which may activate downstream signals to initiate transcription of AMP genes. Moreover, a multitude of cell lines have been established from various salmonid species, making it possible to study host-pathogen interactions in vitro, and several of these cell lines have been shown to express various AMPs. In this review, the structure, function, transcriptional regulation, and immunomodulatory role of salmonid AMPs are highlighted in health and disease. It is important to characterize and understand how salmonid AMPs function as this may lead to a better understanding of host-pathogen interactions with implications for aquaculture and medicine.

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Manoharan, Manovina, and Thamarai Selvi Balasubramaniam. "An Extensive Review on Production, Purification, and Bioactive Application of Different Classes of Bacteriocin." Journal of Tropical Biodiversity and Biotechnology 7, no. 3 (September 9, 2022): 72735. http://dx.doi.org/10.22146/jtbb.72735.

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Lactic Acid Bacteria (LAB) synthesize various metabolites during their growth phase and are Generally Recognized as Safe (GRAS) and Qualified Presumption of Safety (QPS). Ribosomally synthesized Antimicrobial Peptides (AMP) or Bacteriocins from the genera of Lactic Acid Bacteria and other prokaryotic genera are cationic, heat-stable, amphiphilic and the membrane permeabilizing peptides built with an excess amount of lysyl and arginyl residues. Antimicrobial compounds produced by LAB depend on the physical and biological conditions of microbial culture. Different classes of bacteriocin are produced by both Gram-positive and Gram-negative bacteria. The production of bacteriocin is influenced by various environmental factors. Bacteriocin has a wide variety of applications in various fields. The application spectrum of bacteriocins can be expanded in various domains such as food processing, biomedical, and personal care due to the increase in the number of newly discovered bacteriocins. Bacteriocins acquire a wide spectrum of antimicrobial activity with minimal level of cytotoxicity. In addition, bacteriocins were studied for their anticancer activity against different cancer cell lines. Selective binding of bacteriocins (cationic) towards cancer cells (anionic) increases the cytotoxicity of cancer cells. Bacteriocin peptides initiate necrosis by communicating with the cell surface which selectively targets and kills the cells with tumor formation and does not cause any damage to the normal healthy cells. In this review, the bacteriocins synthesized from lactic acid bacteria along with their interaction with cancer cell lines and other applications are discussed along with a few examples of other bioactive compounds produced by LAB.

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Wang, Chenxuan, Naomi A. Biok, Karthik Nayani, Xiaoguang Wang, Hongseung Yeon, Chi-Kuen Derek Ma, Samuel H. Gellman, and Nicholas L. Abbott. "Cationic Side Chain Identity Directs the Hydrophobically Driven Self-Assembly of Amphiphilic β-Peptides in Aqueous Solution." Langmuir 37, no. 11 (March 8, 2021): 3288–98. http://dx.doi.org/10.1021/acs.langmuir.0c03255.

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Reijmar, Karin, Katarina Edwards, Karl Andersson, and Víctor Agmo Hernández. "Characterizing and Controlling the Loading and Release of Cationic Amphiphilic Peptides onto and from PEG-Stabilized Lipodisks." Langmuir 32, no. 46 (November 7, 2016): 12091–99. http://dx.doi.org/10.1021/acs.langmuir.6b03012.

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Ruczyński, Jarosław, Brygida Parfianowicz, Piotr Mucha, Katarzyna Wiśniewska, Lidia Piechowicz, and Piotr Rekowski. "Structure–Activity Relationship of New Chimeric Analogs of Mastoparan from the Wasp Venom Paravespula lewisii." International Journal of Molecular Sciences 23, no. 15 (July 27, 2022): 8269. http://dx.doi.org/10.3390/ijms23158269.

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Mastoparan (MP) is an antimicrobial cationic tetradecapeptide with the primary structure INLKALAALAKKIL-NH2. This amphiphilic α-helical peptide was originally isolated from the venom of the wasp Paravespula lewisii. MP shows a variety of biological activities, such as inhibition of the growth of Gram-positive and Gram-negative bacteria, as well as hemolytic activity and activation of mast cell degranulation. Although MP appears to be toxic, studies have shown that its analogs have a potential therapeutic application as antimicrobial, antiviral and antitumor agents. In the present study we have designed and synthesized several new chimeric mastoparan analogs composed of MP and other biologically active peptides such as galanin, RNA III inhibiting peptide (RIP) or carrying benzimidazole derivatives attached to the ε-amino side group of Lys residue. Next, we compared their antimicrobial activity against three reference bacterial strains and conformational changes induced by membrane-mimic environments using circular dichroism (CD) spectroscopy. A comparative analysis of the relationship between the activity of peptides and the structure, as well as the calculated physicochemical parameters was also carried out. As a result of our structure–activity study, we have found two analogs of MP, MP-RIP and RIP-MP, with interesting properties. These two analogs exhibited a relatively high antibacterial activity against S. aureus compared to the other MP analogs, making them a potentially attractive target for further studies. Moreover, a comparative analysis of the relationship between peptide activity and structure, as well as the calculated physicochemical parameters, may provide information that may be useful in the design of new MP analogs.

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Locock, Katherine E. S., Thomas D. Michl, Hans J. Griesser, Matthias Haeussler, and Laurence Meagher. "Structure–activity relationships of guanylated antimicrobial polymethacrylates." Pure and Applied Chemistry 86, no. 8 (August 20, 2014): 1281–91. http://dx.doi.org/10.1515/pac-2014-0213.

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AbstractHost-defense antimicrobial peptides (AMPs) are a promising lead in the search for novel antibiotics. Many of these peptides exhibit broad-spectrum antibacterial ability, low toxicity toward human cells, and little susceptibility to induction of bacterial resistance. Our research focuses on the development of synthetic polymers that are able to mimic the amphiphilic and cation-rich characteristics of AMPs. This derives bioactive polymers that retain the activity profile of AMPs while utilizing a construct that is less expensive and easier to produce and manipulate chemically. This review details structure–activity relationships (SARs) of a new class of arginine-rich, synthetic AMP mimicking polymers (SAMPs), the guanylated polymethacrylates. These are contrasted with those of amine-based polymers that are mimics of lysine-rich AMPs. The ideal composition for candidates for practical applications was identified as those containing guanidines as a cation source, having a low molecular weight and a low level of lipophilicity. This gave polymers with high potency against Gram-positive strains of bacteria (e.g., Staphylococcus epidermidis MIC = 10 μg/mL) and low toxicity towards human red blood cells (<4% hemolysis at given MIC). This work emphasizes the need to rationalize observed biological activities based not purely on the global lipophilic and cationic character of polymers but rather to consider the profound effect that specific pendant functional groups may have on the potency, selectivity, and mechanisms behind the action of antimicrobial polymers.

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Ergene, Cansu, and Edmund F. Palermo. "Antimicrobial Synthetic Polymers: An Update on Structure-Activity Relationships." Current Pharmaceutical Design 24, no. 8 (May 14, 2018): 855–65. http://dx.doi.org/10.2174/1381612824666180213140732.

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The rising incidence of antibiotic-resistant infections, combined with a declining number of new antibiotic drug approvals, has generated an alarming therapeutic gap that critically undermines public health. Host Defense Peptides (HDPs), sometimes referred to as “Nature’s Antibiotics”, are short chain, amphiphilic and cationic peptide sequences found in all multicellular organisms as part of their innate immunity. While there is a vast diversity in terms of HDP sequence and secondary structure, they all seem to share physiochemical characteristics that can be appropriated for macromolecular design by the synthetic polymer chemist. Over the past decade, remarkable progress has been made in the design and synthesis of polymer-based materials that effectively mimic HDP action – broad-spectrum antibacterial potency, rapid bactericidal kinetics, and minimal toxicity to human cells – while offering the additional benefits of low cost, high scalability, and lower propensity to induce resistance, relative to their peptide-based counterparts. A broad range of different macromolecular structures and architectures have been explored in this design space, including polynorbornenes, poly(meth)acrylates, poly(meth)acrylamides, nylon-2 polymers, and polycarbonates, to name a just few. Across all of these diverse chemical categories, the key determinants of antibacterial and hemolytic activity are the same as in HDPs: net cationic charge at neutral pH, well-balanced facial amphiphilicity, and the molecular weight of the compounds. In this review, we focus in particular on recent progress in the polymethacrylate category first pioneered by Kuroda and DeGrado and later modified, expanded upon and rigorously optimized by Kuroda’s and many other groups. Key findings and future challenges will be highlighted.

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Iwata, Takahiro, Hisaaki Hirose, Kentarou Sakamoto, Yusuke Hirai, Jan Vincent V. Arafiles, Misao Akishiba, Miki Imanishi, and Shiroh Futaki. "Liquid Droplet Formation and Facile Cytosolic Translocation of IgG in the Presence of Attenuated Cationic Amphiphilic Lytic Peptides." Angewandte Chemie 133, no. 36 (July 8, 2021): 19957–65. http://dx.doi.org/10.1002/ange.202105527.

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Iwata, Takahiro, Hisaaki Hirose, Kentarou Sakamoto, Yusuke Hirai, Jan Vincent V. Arafiles, Misao Akishiba, Miki Imanishi, and Shiroh Futaki. "Liquid Droplet Formation and Facile Cytosolic Translocation of IgG in the Presence of Attenuated Cationic Amphiphilic Lytic Peptides." Angewandte Chemie International Edition 60, no. 36 (July 9, 2021): 19804–12. http://dx.doi.org/10.1002/anie.202105527.

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Murata, Masayuki, Sho Takahashi, Satoshi Kagiwada, Atsushi Suzuki, and Shunichi Ohnishi. "pH-Dependent membrane fusion and vesiculation of phospholipid large unilamellar vesicles induced by amphiphilic anionic and cationic peptides." Biochemistry 31, no. 7 (February 1992): 1986–92. http://dx.doi.org/10.1021/bi00122a013.

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Riahifard, Neda, Saghar Mozaffari, Taibah Aldakhil, Francisco Nunez, Qamar Alshammari, Saud Alshammari, Jason Yamaki, Keykavous Parang, and Rakesh Tiwari. "Design, Synthesis, and Evaluation of Amphiphilic Cyclic and Linear Peptides Composed of Hydrophobic and Positively-Charged Amino Acids as Antibacterial Agents." Molecules 23, no. 10 (October 22, 2018): 2722. http://dx.doi.org/10.3390/molecules23102722.

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Antimicrobial peptides (AMPs) contain amphipathic structures and are derived from natural resources. AMPs have been found to be effective in treating the infections caused by antibiotic-resistant bacteria (ARB), and thus, are potential lead compounds against ARB. AMPs’ physicochemical properties, such as cationic nature, amphiphilicity, and their size, will provide the opportunity to interact with membrane bilayers leading to damage and death of microorganisms. Herein, AMP analogs of [R4W4] were designed and synthesized by changing the hydrophobicity and cationic nature of the lead compound with other amino acids to provide insights into a structure-activity relationship against selected model Gram-negative and Gram-positive pathogens. Clinical resistant strains of methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli) were used in the studies. Our results provided information about the structural requirements for optimal activity of the [R4W4] template. When tryptophan was replaced with other hydrophobic amino acids, such as phenylalanine, tyrosine, alanine, leucine, and isoleucine, the antibacterial activities were significantly reduced with MIC values of >128 µg/mL. Furthermore, a change in stereochemistry caused by d-arginine, and use of N-methyltryptophan, resulted in a two-fold reduction of antibacterial activity. It was found that the presence of tryptophan is critical for antibacterial activity, and could not be substituted with other hydrophobic residues. The study also confirmed that cyclic peptides generally showed higher antibacterial activities when compared with the corresponding linear counterparts. Furthermore, by changing tryptophan numbers in the compound while maintaining a constant number of arginine, we determined the optimal number of tryptophan residues to be four, as shown when the number of tryptophan residues increased, a decrease in activity was observed.

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Yu, Tsz Tin, Rajesh Kuppusamy, Muhammad Yasir, Md Musfizur Hassan, Manjulatha Sara, Junming Ho, Mark D. P. Willcox, David StC Black, and Naresh Kumar. "Polyphenylglyoxamide-Based Amphiphilic Small Molecular Peptidomimetics as Antibacterial Agents with Anti-Biofilm Activity." International Journal of Molecular Sciences 22, no. 14 (July 8, 2021): 7344. http://dx.doi.org/10.3390/ijms22147344.

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The rapid emergence of drug-resistant bacteria is a major global health concern. Antimicrobial peptides (AMPs) and peptidomimetics have arisen as a new class of antibacterial agents in recent years in an attempt to overcome antibiotic resistance. A library of phenylglyoxamide-based small molecular peptidomimetics was synthesised by incorporating an N-alkylsulfonyl hydrophobic group with varying alkyl chain lengths and a hydrophilic cationic group into a glyoxamide core appended to phenyl ring systems. The quaternary ammonium iodide salts 16d and 17c showed excellent minimum inhibitory concentration (MIC) of 4 and 8 μM (2.9 and 5.6 μg/mL) against Staphylococcus aureus, respectively, while the guanidinium hydrochloride salt 34a showed an MIC of 16 μM (8.5 μg/mL) against Escherichia coli. Additionally, the quaternary ammonium iodide salt 17c inhibited 70% S. aureus biofilm formation at 16 μM. It also disrupted 44% of pre-established S. aureus biofilms at 32 μM and 28% of pre-established E. coli biofilms 64 μM, respectively. A cytoplasmic membrane permeability study indicated that the synthesised peptidomimetics acted via disruption and depolarisation of membranes. Moreover, the quaternary ammonium iodide salts 16d and 17c were non-toxic against human cells at their therapeutic dosages against S. aureus.

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Hadianamrei, Roja, Mhd Anas Tomeh, Stephen Brown, Jiqian Wang, and Xiubo Zhao. "Correlation between the secondary structure and surface activity of β-sheet forming cationic amphiphilic peptides and their anticancer activity." Colloids and Surfaces B: Biointerfaces 209 (January 2022): 112165. http://dx.doi.org/10.1016/j.colsurfb.2021.112165.

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Tisch, D., Y. Sharoni, M. Danilenko, and I. Aviram. "The assembly of neutrophil NADPH oxidase: effects of mastoparan and its synthetic analogues." Biochemical Journal 310, no. 2 (September 1, 1995): 715–19. http://dx.doi.org/10.1042/bj3100715.

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Detergent-mediated activation of the phagocyte superoxide-generating NADPH oxidase requires the participation of at least four proteins: the membrane-bound heterodimeric cytochrome b558 and three cytosolic components, p47-phox, p67-phox and a Rac1/Rac2 protein. Peptides corresponding to sequences of different subunits of NADPH oxidase have been used as probes of the mechanism and sequence of assembly of the active complex. In the present study effects of mastoparans on activation of NADPH oxidase were investigated. Mastoparans are wasp venom cationic amphiphilic tetradecapeptides capable of modulation of various cellular activities. Natural mastoparans, as well as several synthetic mastoparan analogues, unrelated to oxidase components, blocked activation of the oxidase in the cell-free system (EC50 = 1.5 microM) and in guanosine 5′-[gamma-thio]triphosphate (GTP[S])/ATP-stimulated neutrophils permeabilized with streptolysin O. In the cell-free system the effect was not relieved by raising the detergent concentration and could not be ascribed to changes in critical micellar concentration values of the activating SDS or arachidonate. Chromatography of neutrophil cytosol on an immobilized mastoparan column suggested interaction of cytosolic p47-phox and p67-phox with the peptide. In spite of this interaction mastoparan did not interfere with translocation of p47-phox and p67-phox to the cell membranes.

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Balachandran, Chandrasekar, Kenta Yokoi, Kana Naito, Jebiti Haribabu, Yuichi Tamura, Masakazu Umezawa, Koji Tsuchiya, Toshitada Yoshihara, Seiji Tobita, and Shin Aoki. "Cyclometalated Iridium(III) Complex–Cationic Peptide Hybrids Trigger Paraptosis in Cancer Cells via an Intracellular Ca2+ Overload from the Endoplasmic Reticulum and a Decrease in Mitochondrial Membrane Potential." Molecules 26, no. 22 (November 21, 2021): 7028. http://dx.doi.org/10.3390/molecules26227028.

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In our previous paper, we reported that amphiphilic Ir complex–peptide hybrids (IPHs) containing basic peptides such as KK(K)GG (K: lysine, G: glycine) (e.g., ASb-2) exhibited potent anticancer activity against Jurkat cells, with the dead cells showing a strong green emission. Our initial mechanistic studies of this cell death suggest that IPHs would bind to the calcium (Ca2+)–calmodulin (CaM) complex and induce an overload of intracellular Ca2+, resulting in the induction of non-apoptotic programmed cell death. In this work, we conduct a detailed mechanistic study of cell death induced by ASb-2, a typical example of IPHs, and describe how ASb-2 induces paraptotic programmed cell death in a manner similar to that of celastrol, a naturally occurring triterpenoid that is known to function as a paraptosis inducer in cancer cells. It is suggested that ASb-2 (50 µM) induces ER stress and decreases the mitochondrial membrane potential (ΔΨm), thus triggering intracellular signaling pathways and resulting in cytoplasmic vacuolization in Jurkat cells (which is a typical phenomenon of paraptosis), while the change in ΔΨm values is negligibly induced by celastrol and curcumin. Other experimental data imply that both ASb-2 and celastrol induce paraptotic cell death in Jurkat cells, but this induction occurs via different signaling pathways.

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Kuzmenkov, Alexey I., Maria Y. Sachkova, Sergey I. Kovalchuk, Eugene V. Grishin, and Alexander A. Vassilevski. "Lachesana tarabaevi, an expert in membrane-active toxins." Biochemical Journal 473, no. 16 (August 11, 2016): 2495–506. http://dx.doi.org/10.1042/bcj20160436.

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In the present study, we show that venom of the ant spider Lachesana tarabaevi is unique in terms of molecular composition and toxicity. Whereas venom of most spiders studied is rich in disulfide-containing neurotoxic peptides, L. tarabaevi relies on the production of linear (no disulfide bridges) cytolytic polypeptides. We performed full-scale peptidomic examination of L. tarabaevi venom supported by cDNA library analysis. As a result, we identified several dozen components, and a majority (∼80% of total venom protein) exhibited membrane-active properties. In total, 33 membrane-interacting polypeptides (length of 18–79 amino acid residues) comprise five major groups: repetitive polypeptide elements (Rpe), latarcins (Ltc), met-lysines (MLys), cyto-insectotoxins (CIT) and latartoxins (LtTx). Rpe are short (18 residues) amphiphilic molecules that are encoded by the same genes as antimicrobial peptides Ltc 4a and 4b. Isolation of Rpe confirms the validity of the iPQM (inverted processing quadruplet motif) proposed to mark the cleavage sites in spider toxin precursors that are processed into several mature chains. MLys (51 residues) present ‘idealized’ amphiphilicity when modelled in a helical wheel projection with sharply demarcated sectors of hydrophobic, cationic and anionic residues. Four families of CIT (61–79 residues) are the primary weapon of the spider, accounting for its venom toxicity. Toxins from the CIT 1 and 2 families have a modular structure consisting of two shorter Ltc-like peptides. We demonstrate that in CIT 1a, these two parts act in synergy when they are covalently linked. This finding supports the assumption that CIT have evolved through the joining of two shorter membrane-active peptides into one larger molecule.

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RAJ, Periathamby Antony, Kavitha J. ANTONYRAJ, and Thonthi KARUNAKARAN. "Large-scale synthesis and functional elements for the antimicrobial activity of defensins." Biochemical Journal 347, no. 3 (April 25, 2000): 633–41. http://dx.doi.org/10.1042/bj3470633.

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Human neutrophil defensins, and their analogues incorporating anionic, hydrophobic or cationic residues at the N- and C-termini, were synthesized by solid-phase procedures. The synthetic defensins were examined for their microbicidal activity against Candida albicans, two Gram-negative bacteria (Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis) and two Gram-positive bacteria (Streptococcus gordonii and Streptococcus mutans). The human neutrophil peptide 1 (HNP1) and HNP2 were found to be potent candidacidal agents. HNP3, which differs by one amino acid at the N-terminus of its sequence, was totally inactive. The Gram-negative bacteria A. actinomycetemcomitans and P. gingivalis and the Gram-positive bacteria S. gordonii and S. mutans were insensitive to human defensins. However, the insertion of two basic residues, such as arginine, at both the N-terminus and the C-terminus of HNP2 significantly enhanced antifungal and antibacterial activity. The addition of anionic residues, such as aspartic acid, at the N- and C-termini rendered the molecule totally inactive. The presence of two hydrophobic amino acids, such as valine, at the N-terminus of HNP2 and of two basic arginine residues at its C-terminus resulted in molecules that were optimally active against these oral pathogens. The results suggest that the N- and C-terminal residues in defensin peptides are the crucial functional elements that determine their microbicidal potency. The three-dimensional structure of all defensins constitutes the same amphiphilic β-sheet structure, with the polar face formed by the N- and C-terminal residues playing an important role in defining microbicidal potency and the antimicrobial spectrum. The enhanced microbicidal activity observed for defensin peptides with two basic residues at both the N- and C-termini could be due to optimization of the amphiphilicity of the structure, which could facilitate specific interactions with the microbial membranes.

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Journal articles on the topic 'Cationic Amphiphilic Peptides'

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