oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Titanium Immobilized with an Antimicrobial Peptide Derived from Histatin Accelerates the Differentiation of Osteoblastic Cell Line, MC3T3-E1  [PDF]
Seicho Makihira,Takahiro Shuto,Hiroki Nikawa,Keishi Okamoto,Yuichi Mine,Yuko Takamoto,Masaru Ohara,Koichiro Tsuji
International Journal of Molecular Sciences , 2010, DOI: 10.3390/ijms11041458
Abstract: The objective of this study was to evaluate the effect of titanium immobilized with a cationic antimicrobial peptide (JH8194) derived from histatin on the biofilm formation of Porphyromonas gingivalis and differentiation of osteoblastic cells (MC3T3-E1). The titanium specimens (Ti) were immobilized with JH8194, according to the method previously described. The colonization of P. gingivalis on JH8194-Ti was significantly lower than that on control- and blocking-Ti. JH8194-Ti enhanced the mRNA expressions of Runx2 and OPN, and ALPase activity in the MC3T3-E1, as compared with those of control- and blocking-Ti. These results, taken together, suggested the possibility that JH8194-Ti may be a potential aid to shorten the period of acquiring osseointegration.
The Antimicrobial Peptide Histatin-5 Causes a Spatially Restricted Disruption on the Candida albicans Surface, Allowing Rapid Entry of the Peptide into the Cytoplasm  [PDF]
A. Brian Mochon,Haoping Liu
PLOS Pathogens , 2008, DOI: 10.1371/journal.ppat.1000190
Abstract: Antimicrobial peptides play an important role in host defense against microbial pathogens. Their high cationic charge and strong amphipathic structure allow them to bind to the anionic microbial cell membrane and disrupt the membrane bilayer by forming pores or channels. In contrast to the classical pore-forming peptides, studies on histatin-5 (Hst-5) have suggested that the peptide is transported into the cytoplasm of Candida albicans in a non-lytic manner, and cytoplasmic Hst-5 exerts its candicidal activities on various intracellular targets, consistent with its weak amphipathic structure. To understand how Hst-5 is internalized, we investigated the localization of FITC-conjugated Hst-5. We find that Hst-5 is internalized into the vacuole through receptor-mediated endocytosis at low extracellular Hst-5 concentrations, whereas under higher physiological concentrations, Hst-5 is translocated into the cytoplasm through a mechanism that requires a high cationic charge on Hst-5. At intermediate concentrations, two cell populations with distinct Hst-5 localizations were observed. By cell sorting, we show that cells with vacuolar localization of Hst-5 survived, while none of the cells with cytoplasmic Hst-5 formed colonies. Surprisingly, extracellular Hst-5, upon cell surface binding, induces a perturbation on the cell surface, as visualized by an immediate and rapid internalization of Hst-5 and propidium iodide or rhodamine B into the cytoplasm from the site using time-lapse microscopy, and a concurrent rapid expansion of the vacuole. Thus, the formation of a spatially restricted site in the plasma membrane causes the initial injury to C. albicans and offers a mechanism for its internalization into the cytoplasm. Our study suggests that, unlike classical channel-forming antimicrobial peptides, action of Hst-5 requires an energized membrane and causes localized disruptions on the plasma membrane of the yeast. This mechanism of cell membrane disruption may provide species-specific killing with minimal damage to microflora and the host and may be used by many other antimicrobial peptides.
Side Chain Hydrophobicity Modulates Therapeutic Activity and Membrane Selectivity of Antimicrobial Peptide Mastoparan-X  [PDF]
Jonas R. Henriksen, Thomas Etzerodt, Torben Gjetting, Thomas L. Andresen
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0091007
Abstract: The discovery of new anti-infective compounds is stagnating and multi-resistant bacteria continue to emerge, threatening to end the “antibiotic era”. Antimicrobial peptides (AMPs) and lipo-peptides such as daptomycin offer themselves as a new potential class of antibiotics; however, further optimization is needed if AMPs are to find broad use as antibiotics. In the present work, eight analogues of mastoparan-X (MPX) were investigated, having side chain modifications in position 1, 8 and 14 to modulate peptide hydrophobicity. The self-association properties of the peptides were characterized, and the peptide-membrane interactions in model membranes were compared with the bactericidal and haemolytic properties. Alanine substitution at position 1 and 14 resulted in higher target selectivity (red blood cells versus bacteria), but also decreased bactericidal potency. For these analogues, the gain in target selectivity correlated to biophysical parameters showing an increased effective charge and reduction in the partitioning coefficient for membrane insertion. Introduction of an unnatural amino acid, with an octyl side chain by amino acid substitution, at positions 1, 8 and 14 resulted in increased bactericidal potency at the expense of radically reduced membrane target selectivity. Overall, optimized membrane selectivity or bactericidal potency was achieved by changes in side chain hydrophobicity of MPX. However, enhanced potency was achieved at the expense of selectivity and vice versa in all cases.
Transmembrane and Antimicrobial Peptides. Hydrophobicity, Amphiphilicity and Propensity to Aggregation  [PDF]
M. Pirtskhalava,B. Vishnepolsky,M. Grigolava
Quantitative Biology , 2013,
Abstract: Development of the new antimicrobial agents against antibiotic resistance pathogens is the nowadays challenge. Antimicrobial peptides (AMP) occur as important defence agents in many organisms and offer a viable alternative to conventional antibiotics. Therefore they have become increasingly recognized in current research as templates for prospective antibiotic agents. The efficient designing of the new antimicrobials on the basis of antimicrobial peptides requires comprehensive knowledge on those general physical-chemical characteristics which allow to differ antimicrobial peptides from non-active against microbs ones. According to supposed mechanisms of action, AMP interact with and physically disrupt the bacterial membranes. Consequently, hydrophobicity, amphiphilicity and intrinsic aggregation propensities are considered as such major characteristics of the peptide, which determine the results of peptide-membrane interactions. For some kind of peptides such characteristics as hydrophobicity, amphiphilicity and aggregation bias determines their ability to compose transmembrane domain of the membrane protein, whilst for others the same properties are respond for their antimicrpobial activity, i.e. give them ability of membrane permeability and its damage. In this review we analyze the data about hydrophobicity, amphiphilicity and intrinsic aggregation propensities available in literature in order to compare antimicrobial and transmembrane peptides and show what is the common and what is the difference in this respect between them.
A Novel Immune Evasion Strategy of Candida albicans: Proteolytic Cleavage of a Salivary Antimicrobial Peptide  [PDF]
Timothy F. Meiller, Bernhard Hube, Lydia Schild, Mark E. Shirtliff, Mark A. Scheper, Robert Winkler, Amy Ton, Mary Ann Jabra-Rizk
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0005039
Abstract: Oropharyngeal candidiasis is an opportunistic infection considered to be a harbinger of AIDS. The etiologic agent Candida albicans is a fungal species commonly colonizing human mucosal surfaces. However, under conditions of immune dysfunction, colonizing C. albicans can become an opportunistic pathogen causing superficial or even life-threatening infections. The reasons behind this transition, however, are not clear. In the oral cavity, salivary antimicrobial peptides are considered to be an important part of the host innate defense system in the prevention of microbial colonization. Histatin-5 specifically has exhibited potent activity against C. albicans. Our previous studies have shown histatin-5 levels to be significantly reduced in the saliva of HIV+ individuals, indicating an important role for histatin-5 in keeping C. albicans in its commensal stage. The versatility in the pathogenic potential of C. albicans is the result of its ability to adapt through the regulation of virulence determinants, most notably of which are proteolytic enzymes (Saps), involved in tissue degradation. In this study, we show that C. albicans cells efficiently and rapidly degrade histatin-5, resulting in loss of its anti-candidal potency. In addition, we demonstrate that this cellular activity is due to proteolysis by a member of the secreted aspartic proteases (Sap) family involved in C. albicans pathogenesis. Specifically, the proteolysis was attributed to Sap9, in turn identifying histatin-5 as the first host-specific substrate for that isoenzyme. These findings demonstrate for the first time the ability of a specific C. albicans enzyme to degrade and deactivate a host antimicrobial peptide involved in the protection of the oral mucosa against C. albicans, thereby providing new insights into the factors directing the transition of C. albicans from commensal to pathogen, with important clinical implications for alternative therapy. This report characterizes the first defined mechanism behind the enhanced susceptibility of HIV+ individuals to oral candidiasis since the emergence of HIV.
On the hydrophobicity of peptides: Comparing empirical predictions of peptide log P values  [cached]
Sarah J. Thompson,Channa K. Hattotuwagama,John D. Holliday,Darren R. Flower
Bioinformation , 2006,
Abstract: Peptides are of great therapeutic potential as vaccines and drugs. Knowledge of physicochemical descriptors, including the partition coefficient logP, is useful for the development of predictive Quantitative Structure-Activity Relationships (QSARs). We have investigated the accuracy of available programs for the prediction of logP values for peptides with known experimental values obtained from the literature. Eight prediction programs were tested, of which seven programs were fragment-based methods: XLogP, LogKow, PLogP, ACDLogP, AlogP, Interactive Analysis’s LogP and MlogP; and one program used a whole molecule approach: QikProp. The predictive accuracy of the programs was assessed using r2 values, with ALogP being the most effective (r2 = 0.822) and MLogP the least (r2 = 0.090). We also examined three distinct types of peptide structure: blocked, unblocked, and cyclic. For each study (all peptides, blocked, unblocked and cyclic peptides) the performance of programs rated from best to worse is as follows: all peptides – ALogP, QikProp, PLogP, XLogP, IALogP, LogKow, ACDLogP, and MlogP; blocked peptides – PLogP, XLogP, ACDLogP, IALogP, LogKow, QikProp, ALogP, and MLogP; unblocked peptides – QikProp, IALogP, ALogP, ACDLogP, MLogP, XLogP, LogKow and PLogP; cyclic peptides – LogKow, ALogP, XLogP, MLogP, QikProp, ACDLogP, IALogP. In summary, all programs gave better predictions for blocked peptides, while, in general, logP values for cyclic peptides were under-predicted and those of unblocked peptides were over-predicted.
Effects of Antimicrobial Peptide Revealed by Simulations: Translocation, Pore Formation, Membrane Corrugation and Euler Buckling  [PDF]
Licui Chen,Nana Jia,Lianghui Gao,Weihai Fang,Leonardo Golubovic
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms14047932
Abstract: We explore the effects of the peripheral and transmembrane antimicrobial peptides on the lipid bilayer membrane by using the coarse grained Dissipative Particle Dynamics simulations. We study peptide/lipid membrane complexes by considering peptides with various structure, hydrophobicity and peptide/lipid interaction strength. The role of lipid/water interaction is also discussed. We discuss a rich variety of membrane morphological changes induced by peptides, such as pore formation, membrane corrugation and Euler buckling.
Structure-function relationship of antimicrobial peptide cathelicidin Pc-CATH1
Li Dong,Juan-Juan Yang,Ying Wang,Huan Liu,Li-Xian Mu,Dong-Hai Lin,Ren Lai
Natural Products and Bioprospecting , 2012, DOI: 10.1007/s13659-012-0016-1
Abstract: Cathelicidin Pc-CATH1 is a cathelicidin-derived myeloid antimicrobial peptide identified from Phasianus colchicus with strong antimicrobial activity against most of bacteria and fungi tested, including the clinically isolated (IS) drug-resistant strains. Considering the uniform distribution of net positive charge in both C- and N-terminus sequence of cathelicidin Pc-CATH1 and most of hydrophobic amino acid (aa) residues positioned in middle of the sequence, the antimicrobial peptide was used to investigate the structure-function relationship by truncating gradually N- or C-terminus amino acid residue. More than 10 modified peptide homologues (20–26 aa length) of cathelicidin Pc-CATH1 were found to keep strong antimicrobial abilities. The possible relationships between bioactivities including antimicrobial and hemolytic abilities, components of secondary structure, hydrophobicity, amphipathicity, net charge, and sequence length were investigated. The current work provided suggestions for structural and functional modification of linear, α-helical antimicrobial peptides containing no disulfided bridges.
A Small Peptide with Potential Ability to Promote Wound Healing  [PDF]
Jing Tang, Han Liu, Chen Gao, Lixian Mu, Shilong Yang, Mingqiang Rong, Zhiye Zhang, Jie Liu, Qiang Ding, Ren Lai
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0092082
Abstract: Wound-healing represents a major health burden, such as diabetes-induced skin ulcers and burning. Many works are being tried to find ideal clinical wound-healing biomaterials. Especially, small molecules with low cost and function to promote production of endogenous wound healing agents (i.e. transforming growth factor beta, TGF-β) are excellent candidates. In this study, a small peptide (tiger17, c[WCKPKPKPRCH-NH2]) containing only 11 amino acid residues was designed and proved to be a potent wound healer. It showed strong wound healing-promoting activity in a murine model of full thickness dermal wound. Tiger17 exerted significant effects on three stages of wound healing progresses including (1) the induction of macrophages recruitment to wound site at inflammatory reaction stage; (2) the promotion of the migration and proliferation both keratinocytes and fibroblasts, leading to reepithelialization and granulation tissue formation; and (3) tissue remodeling phase, by promoting the release of transforming TGF-β1 and interleukin 6 (IL-6) in murine macrophages and activating mitogen-activated protein kinases (MAPK) signaling pathways. Considering its easy production, store and transfer and function to promote production of endogenous wound healing agents (TGF-β), tiger17 might be an exciting biomaterial or template for the development of novel wound-healing agents.
Anti-Candidal Activity of Genetically Engineered Histatin Variants with Multiple Functional Domains  [PDF]
Frank G. Oppenheim, Eva J. Helmerhorst, Urs Lendenmann, Gwynneth D. Offner
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0051479
Abstract: The human bodily defense system includes a wide variety of innate antimicrobial proteins. Histatins are small molecular weight proteins produced by the human salivary glands that exhibit antifungal and antibacterial activities. While evolutionarily old salivary proteins such as mucins and proline-rich proteins contain large regions of tandem repeats, relatively young proteins like histatins do not contain such repeated domains. Anticipating that domain duplications have a functional advantage, we genetically engineered variants of histatin 3 with one, two, three, or four copies of the functional domain by PCR and splice overlap. The resulting proteins, designated reHst3 1-mer, reHist3 2-mer, reHis3 3-mer and reHist3 4-mer, exhibited molecular weights of 4,062, 5,919, 7,777, and 9,634 Da, respectively. The biological activities of these constructs were evaluated in fungicidal assays toward Candida albicans blastoconidia and germinated cells. The antifungal activities per mole of protein increased concomitantly with the number of functional domains present. This increase, however, was higher than could be anticipated from the molar concentration of functional domains present in the constructs. The demonstrated increase in antifungal activity may provide an evolutionary explanation why such domain multiplication is a frequent event in human salivary proteins.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.