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Model amphipathic peptide

Zachary B Jenner, Christopher M Crittenden, Martín Gonzalez, Jennifer S Brodbelt, Kerry A Bruns
Antimicrobial peptides (AMPs) occur widely in nature and have been studied for their therapeutic potential. AMPs are of interest due to the large number of possible chemical structural combinations using natural and unnatural amino acids, with varying effects on their biological activities. Using physicochemical properties from known naturally occurring amphipathic cationic AMPs, several hydrocarbon-stapled lipopeptides (HSLPs) were designed, synthesized, and tested for antimicrobial properties. Peptides were chemically modified by N-terminal acylation, C-terminal amidation, and some were hydrocarbon stapled by intramolecular olefin metathesis...
January 10, 2017: Biopolymers
Philip W Fowler, Mark S P Sansom, Reinhart A F Reithmeier
The first transmembrane (TM1) helix in the red cell anion exchanger (AE1, Band 3, SLC4A1) acts as an internal signal anchor that binds the signal recognition particle and directs the nascent polypeptide chain to the endoplasmic reticulum (ER) membrane where it moves from the translocon laterally into the lipid bilayer. The sequence N-terminal to TM1 forms an amphipathic helix that lies at the membrane interface connected to TM1 by a bend at Pro403. Southeast Asian Ovalocytosis (SAO) is a red cell abnormality caused by a nine-amino acid deletion (Ala400-Ala408) at the N-terminus of TM1...
January 9, 2017: Biochemistry
Matthieu Fillion, Maxime Goudreault, Normand Voyer, Burkhard Bechinger, Michèle Auger
Cationic antimicrobial peptides are a component of the innate immune system of several organisms and represent an interesting alternative to fight multiresistant bacteria. In this context, we have elaborated a synthetic peptide scaffold allowing the study of the impact of different molecular determinants on the membrane interactions. The aim of the present study was to elucidate the mechanism of action of two cationic peptides that derive from a neutral 14-mer template peptide and where the hydrophilic portion is composed of a crown ether...
December 13, 2016: Biochemistry
Cibele Nicolaski Pedron, Marcelo Der Torossian Torres, Julia Aparecida da Silva Lima, Pedro Ismael Silva, Fernanda Dias Silva, Vani Xavier Oliveira
Antimicrobial peptides are biologically active molecules produced by a wide range of organisms as an essential component of the innate immune response. They have recently attracted great interest, since they have antimicrobial activity against a broad spectrum of microorganisms. VmCT1 is a cationic peptide from the venom of Vaejovis mexicanus smithi scorpions, which presents antibacterial activity and tends to helical structures. Its analogs were synthesized, characterized and the conformational studies were performed by circular dichroism...
November 24, 2016: European Journal of Medicinal Chemistry
Oleg M Michurin, Sergii Afonin, Marina Berditsch, Constantin G Daniliuc, Anne S Ulrich, Igor V Komarov, Dmytro S Radchenko
Conformationally constrained non-racemizing trifluoromethyl-substituted lysine isosteres [(E)- and (Z)-TCBLys] with charged side chains are presented as a new type of (19) F-NMR labels for peptide studies. Design of the labels, their synthesis, incorporation into peptides and experimental demonstration of their application for solid state NMR studies of membrane-active peptides are described. A series of fluorine-labeled analogues of the helical amphipathic antimicrobial peptide PGLa(Nle) was obtained, in which different lysine residues in the original peptide sequence were replaced, one at a time, by either (E)- or (Z)-TCBLys...
November 14, 2016: Angewandte Chemie
Bhisma N Ratha, Anirban Ghosh, Jeffrey R Brender, Nilanjan Gayen, Humaira Ilyas, Chilukoti Neeraja, Kali P Das, Atin K Mandal, Anirban Bhunia
The aggregation of insulin into amyloid fibers has been a limiting factor in the development of fast acting insulin analogues, creating a demand for excipients that limit aggregation. Despite the potential demand, inhibitors specifically targeting insulin have been few in number. Here we report a non-toxic and serum stable-designed heptapeptide, KR7 (KPWWPRR-NH2), that differs significantly from the primarily hydrophobic sequences that have been previously used to interfere with insulin amyloid fibrillation...
November 4, 2016: Journal of Biological Chemistry
Alan J Waring, Monik Gupta, Larry M Gordon, Gary Fujii, Frans J Walther
Surfactant protein B (SP-B; 79 residues) is a member of the saposin superfamily and plays a pivotal role in lung function. The N- and C-terminal regions of SP-B, cross-linked by two disulfides, were theoretically predicted to fold as charged amphipathic helices, suggesting participation in surfactant activities. Previous studies with oxidized Super Mini-B (SMB), a construct based on the N- and C-regions of SP-B (i.e., residues 1-25 and 63-78) joined with a designer turn (-PKGG-) and two disulfides, indicated that freshly prepared SMB in lipids folded as a surface active, α-helix-hairpin...
December 2016: Biochimica et Biophysica Acta
Krista Freimann, Piret Arukuusk, Kaido Kurrikoff, Luís Daniel Ferreira Vasconcelos, Kadi-Liis Veiman, Julia Uusna, Helerin Margus, Alfonso T Garcia-Sosa, Margus Pooga, Ülo Langel
As the field of gene therapy progresses, an increasingly urgent need has arisen for efficient and non-toxic vectors for the in vivo delivery of nucleic acids. Cell-penetrating peptides (CPP) are very efficient transfection reagents in vitro, however, their application in vivo needs improvement. To enhance in vivo transfection we designed various CPPs based on previous knowledge of internalization studies and physiochemical properties of NickFect (NF) nanoparticles. We show that increment of the helicity of these Transportan10 analogues improves the transfection efficiency...
November 10, 2016: Journal of Controlled Release: Official Journal of the Controlled Release Society
Vivian Montero-Alejo, Gerardo Corzo, Javier Porro-Suardíaz, Zenia Pardo-Ruiz, Erick Perera, Leandro Rodríguez-Viera, Gabriela Sánchez-Díaz, Erix Wiliam Hernández-Rodríguez, Carlos Álvarez, Steve Peigneur, Jan Tytgat, Rolando Perdomo-Morales
Beta_defensin have been solely found in vertebrates until β-defensin-like peptides were described as transcript isoforms in two species of Panulirus genus. They were considered as putative antimicrobials since their biological activity have not been demonstrated. Here we purified and characterized a defensin-like peptide from the hemocytes of spiny lobster P. argus, hereafter named panusin. Structurally, panusin presents a cysteine-stabilized α/β motif, and is prone to form homodimers. Biological activity of panusin showed broad-spectrum antimicrobial activity, characterized for being strikingly salt-resistant...
February 2017: Developmental and Comparative Immunology
G M Anantharamaiah, David W Garber, C Roger White
Apolipoprotein (apo)A-I and apoE are the two protein components that have been extensively investigated for their anti-atherogenic properties. Both apolipoproteins possess amphipathic helical structures, responsible for the solubilization of lipids. While apoA-I possesses class A amphipathic helical structures, apoE possesses a 59 residue long amphipathic helical domain linked to a four helix bundle containing the Arg-rich, 10 residue receptor binding domain. An 18 residue model peptide (18A) was designed to mimic the amphipathic helical domains of apoA-I...
2016: Protein and Peptide Letters
Sarah N Ramsook, Joyce Ni, Shokofeh Shahangian, Ana Vakiloroayaei, Naveen Khan, Jamie J Kwan, Logan W Donaldson
Group E members of the SOX transcription factor family include SOX8, SOX9, and SOX10. Preceding the high mobility group (HMG) domain in each of these proteins is a thirty-eight amino acid region that supports the formation of dimers on promoters containing tandemly inverted sites. The purpose of this study was to obtain new structural insights into how the dimerization region functions with the HMG domain. From a mutagenic scan of the dimerization region, the most essential amino acids of the dimerization region were clustered on the hydrophobic face of a single, predicted amphipathic helix...
2016: PloS One
W F Drew Bennett, Chun Kit Hong, Yi Wang, D Peter Tieleman
Due to antimicrobial resistance, the development of new drugs to combat bacterial and fungal infections is an important area of research. Nature uses short, charged, and amphipathic peptides for antimicrobial defense, many of which disrupt the lipid membrane in addition to other possible targets inside the cell. Computer simulations have revealed atomistic details for the interactions of antimicrobial peptides and cell-penetrating peptides with lipid bilayers. Strong interactions between the polar interface and the charged peptides can induce bilayer deformations - including membrane rupture and peptide stabilization of a hydrophilic pore...
September 13, 2016: Journal of Chemical Theory and Computation
Megan B Miller, Yan Yan, Yi Wu, Bing Hao, Richard E Mains, Betty A Eipper
Kalirin (Kal), a dual Rho GDP/GTP exchange factor (GEF), plays essential roles within and outside the nervous system. Tissue-specific, developmentally regulated alternative splicing generates isoforms with one (Kal7) or two (Kal9, Kal12) GEF domains along with a kinase (Kal12) domain; while Kal9 and Kal12 are crucial for neurite outgrowth, Kal7 plays important roles in spine maintenance and synaptic plasticity. Tissue-specific usage of alternate Kalrn promoters (A, B, C, D) places four different peptides before the Sec14 domain...
July 28, 2016: Journal of Neurochemistry
Lucie Kocourková, Pavlína Novotná, Sabína Čujová, Václav Čeřovský, Marie Urbanová, Vladimír Setnička
Antimicrobial peptides have long been considered as promising compounds against drug-resistant pathogens. In this work, we studied the secondary structure of antimicrobial peptides melectin and antapin using electronic (ECD) and vibrational circular dichroism (VCD) spectroscopies that are sensitive to peptide secondary structures. The results from quantitative ECD spectral evaluation by Dichroweb and CDNN program and from the qualitative evaluation of the VCD spectra were compared. The antimicrobial activity of the selected peptides depends on their ability to adopt an amphipathic α-helical conformation on the surface of the bacterial membrane...
January 5, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Seoyeon Kim, Soonsil Hyun, Yuri Lee, Yan Lee, Jaehoon Yu
Cell-penetrating peptides (CPPs) often have cationic and amphipathic characteristics that are commonly associated with α-helical peptides. These features give CPPs both membrane demolishing and penetrating abilities. To make CPPs safe for biomedical applications, their toxicities resulting from their membrane demolishing abilities must be removed while their cell penetrating abilities must be retained. In this study, we systematically constructed mutants of the amphipathic α-helical model peptide (LKKLLKLLKKLLKLAG, LK peptide)...
September 12, 2016: Biomacromolecules
Saumya Bajaj, Debajit Dey, Rohan Bhukar, Mohit Kumar, Manidipa Banerjee
In the absence of lipid envelopes and associated fusion proteins, non-enveloped viruses employ membrane lytic peptides to breach the limiting membranes of host cells. Although several of these lytic peptides have been identified and characterized, their manner of deployment and interaction with host membranes remains unclear in most cases. We are using the gamma peptide of Flock House Virus (FHV), a model non-enveloped virus, to understand the mechanistic details of non-enveloped virus interaction with host cell membranes...
August 28, 2016: Journal of Molecular Biology
Alexander V Bocharov, Tinghuai Wu, Irina N Baranova, Anna A Birukova, Denis Sviridov, Tatyana G Vishnyakova, Alan T Remaley, Thomas L Eggerman, Amy P Patterson, Konstantin G Birukov
Synthetic amphipathic helical peptides (SAHPs) designed as apolipoprotein A-I mimetics are known to bind to class B scavenger receptors (SR-Bs), SR-BI, SR-BII, and CD36, receptors that mediate lipid transport and facilitate pathogen recognition. In this study, we evaluated SAHPs, selected for targeting human CD36, by their ability to attenuate LPS-induced inflammation, endothelial barrier dysfunction, and acute lung injury (ALI). L37pA, which targets CD36 and SR-BI equally, inhibited LPS-induced IL-8 secretion and barrier dysfunction in cultured endothelial cells while reducing lung neutrophil infiltration by 40% in a mouse model of LPS-induced ALI...
July 15, 2016: Journal of Immunology: Official Journal of the American Association of Immunologists
Tomo Murayama, Sílvia Pujals, Hisaaki Hirose, Ikuhiko Nakase, Shiroh Futaki
The N-terminal amphipathic helical segment of adenovirus internal protein VI (AdVpVI) plays a critical role in viral infection. Here, we report that the peptide segment corresponding to AdVpVI (positions 33-55) can induce positive membrane curvature together with membrane perturbation. The enhanced perturbation ability of the peptide was observed for membranes containing negatively charged phospholipids. Based on the liposome leakage assay, substitution of leucine at position 40 to other aliphatic (isoleucine) and aromatic (phenylalanine and tryptophan) residues yielded a similar degree of membrane perturbation by the peptides, which was considerably diminished by the substitution to glutamine...
November 4, 2016: Biopolymers
Yongkang He, Xiaofeng He
Antimicrobial peptides (AMPs) have been the focus of intense research towards the finding of a viable alternative to current small-molecule antibiotics, owing to their commonly observed and naturally occurring resistance against pathogens. However, natural peptides have many problems such as low bioavailability and high allergenicity that largely limit the clinical applications of AMPs. In the present study, an integrative protocol that combined chemoinformatics modeling, molecular dynamics simulations, and in vitro susceptibility test was described to design AMPs containing unnatural amino acids (AMP-UAAs)...
September 2016: Biopolymers
Janely Pae, Laura Liivamägi, Dmitri Lubenets, Piret Arukuusk, Ülo Langel, Margus Pooga
Cell-penetrating peptides (CPPs) are considered as one of the most promising tools to mediate the cellular delivery of various biologically active compounds that are otherwise cell impermeable. CPPs can internalize into cells via two different pathways - endocytosis and direct translocation across the plasma membrane. In both cases, the initial step of internalization requires interactions between CPPs and different plasma membrane components. Despite the extensive research, it is not yet fully understood, which of these cell surface molecules mediate the direct translocation of CPPs across the plasma- and endosomal membrane...
August 2016: Biochimica et Biophysica Acta
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