International Journal of Peptides The latest articles from Hindawi Publishing Corporation © 2016 , Hindawi Publishing Corporation . All rights reserved. Mystixin-7 Peptide Protects Ionotropic Glutamatergic Mechanisms against Glutamate-Induced Excitotoxicity In Vitro Mon, 18 Jul 2016 08:17:02 +0000 Hyperactivation of the N-methyl-D-aspartic acid type glutamate receptors (NMDARs) causes glutamate excitotoxicity, a process potentially important for many neurological diseases. This study aims to investigate protective effects of the synthetic corticotrophin-releasing factor-like peptide, mystixin-7 (MTX), on model glutamate-induced excitotoxicity in vitro. The technique online monitoring of electrophysiological parameters (excitatory glutamatergic alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic (AMPAR) and NMDAR-dependent postsynaptic mechanisms) in the olfactory cortex slices was used. Application of L-glutamate in toxic concentration (20 mM) on slices evoked hyperactivation of NMDARs and weaker activation of the AMPARs. Upon further action agonist, the excessive activation of glutamate receptors was replaced by their irreversible blockade. Pretreatment of the slices using MTX in different concentrations (50 and 100 mg/mL) protected both NMDARs and AMPARs from glutamate-induced damage. An enzymatic treatment of MTX reduced hyperactivation of both NMDARs and AMPARs. The present study demonstrated that MTX minipeptide protected the functioning of both NMDARs and AMPARs against glutamate-induced damage. The MTX peptide is a prospective candidate for elaborated medication in treatment of neurological diseases. Anatoly A. Mokrushin Copyright © 2016 Anatoly A. Mokrushin. All rights reserved. Netrin-1 Peptide Is a Chemorepellent in Tetrahymena thermophila Thu, 31 Mar 2016 12:57:01 +0000 Netrin-1 is a highly conserved, pleiotropic signaling molecule that can serve as a neuronal chemorepellent during vertebrate development. In vertebrates, chemorepellent signaling is mediated through the tyrosine kinase, src-1, and the tyrosine phosphatase, shp-2. Tetrahymena thermophila has been used as a model system for chemorepellent signaling because its avoidance response is easily characterized under a light microscope. Our experiments showed that netrin-1 peptide is a chemorepellent in T. thermophila at micromolar concentrations. T. thermophila adapts to netrin-1 over a time course of about 10 minutes. Netrin-adapted cells still avoid GTP, PACAP-38, and nociceptin, suggesting that netrin does not use the same signaling machinery as any of these other repellents. Avoidance of netrin-1 peptide was effectively eliminated by the addition of the tyrosine kinase inhibitor, genistein, to the assay buffer; however, immunostaining using an anti-phosphotyrosine antibody showed similar fluorescence levels in control and netrin-1 exposed cells, suggesting that tyrosine phosphorylation is not required for signaling to occur. In addition, ELISA indicates that a netrin-like peptide is present in both whole cell extract and secreted protein obtained from Tetrahymena thermophila. Further study will be required in order to fully elucidate the signaling mechanism of netrin-1 peptide in this organism. Heather Kuruvilla, Bradley Schmidt, Stephanie Song, Marian Bhajjan, Matthew Merical, Caleb Alley, Christopher Griffin, David Yoder, Josephine Hein, Daniel Kohl, Cambria Puffenberger, David Petroff, Elise Newcomer, Kortney Good, Graham Heston, and Anna Hurtubise Copyright © 2016 Heather Kuruvilla et al. All rights reserved. The Dipeptides Ile-Tyr and Ser-Tyr Exert Distinct Effects on Catecholamine Metabolism in the Mouse Brainstem Thu, 11 Feb 2016 12:12:32 +0000 Catecholamine synthesis and transmission in the brain are influenced by the availability of Tyr in the body. In this study, we compared the effects of oral administration of Tyr-containing dipeptides Ile-Tyr, Ser-Tyr, and Tyr-Pro with Tyr alone on catecholamine metabolism in the mouse brainstem. Among these dipeptides, Ile-Tyr administration led to increases in dopamine, the dopamine metabolites homovanillic acid, and 3,4-dihydroxyphenylacetic acid, compared to administration of Ser-Tyr, Tyr-Pro, or Tyr alone. In comparison, administration of Ser-Tyr induced significantly increasing noradrenaline turnover, while Tyr-Pro administration suppressed dopamine turnover. Therefore, oral administration of Ile-Tyr, Ser-Tyr, and Tyr-Pro differentially affected metabolism of dopamine and noradrenaline. These observations strongly suggest that Tyr-containing dipeptides exert distinct effects on catecholamine metabolism in the brainstem when ingested orally. Kazuki Moriyasu, Takashi Ichinose, Akane Nakahata, Mitsuru Tanaka, Toshiro Matsui, and Shigeki Furuya Copyright © 2016 Kazuki Moriyasu et al. All rights reserved. High Proteolytic Resistance of Spider-Derived Inhibitor Cystine Knots Wed, 30 Dec 2015 11:22:18 +0000 Proteolytic stability in gastrointestinal tract and blood plasma is the major obstacle for oral peptide drug development. Inhibitor cystine knots (ICKs) are linear cystine knot peptides which have multifunctional properties and could become promising drug scaffolds. ProTx-I, ProTx-II, GTx1-15, and GsMTx-4 were spider-derived ICKs and incubated with pepsin, trypsin, chymotrypsin, and elastase in physiological conditions to find that all tested peptides were resistant to pepsin, and ProTx-II, GsMTx-4, and GTx1-15 showed resistance to all tested proteases. Also, no ProTx-II degradation was observed in rat blood plasma for 24 hours in vitro and ProTx-II concentration in circulation decreased to half in 40 min, indicating absolute stability in plasma and fast clearance from the system. So far, linear peptides are generally thought to be unsuitable in vivo, but all tested ICKs were not degraded by pepsin and stomach could be selected for the alternative site of drug absorption for fast onset of the drug action. Since spider ICKs are selective inhibitors of various ion channels which are related to the pathology of many diseases, engineered ICKs will make a novel class of peptide medicines which can treat variety of bothering symptoms. Kyoko Kikuchi, Mika Sugiura, and Tadashi Kimura Copyright © 2015 Kyoko Kikuchi et al. All rights reserved. Peptide-Induced Amyloid-Like Conformational Transitions in Proteins Tue, 08 Sep 2015 07:56:39 +0000 Changes in protein conformation can occur both as part of normal protein functioning and during disease pathogenesis. The most common conformational diseases are amyloidoses. Sometimes the development of a number of diseases which are not traditionally related to amyloidoses is associated with amyloid-like conformational transitions of proteins. Also, amyloid-like aggregates take part in normal physiological processes such as memorization and cell signaling. Several primary structural features of a protein are involved in conformational transitions. Also the protein proteolytic fragments can cause the conformational transitions in the protein. Short peptides which could be produced during the protein life cycle or which are encoded by short open reading frames can affect the protein conformation and function. Vladimir Egorov, Natalia Grudinina, Andrey Vasin, and Dmitry Lebedev Copyright © 2015 Vladimir Egorov et al. All rights reserved. Proteins of Bartonella bacilliformis: Candidates for Vaccine Development Sun, 30 Aug 2015 13:24:29 +0000 Bartonella bacilliformis is the etiologic agent of Carrión’s disease or Oroya fever. B. bacilliformis infection represents an interesting model of human host specificity. The notable differences in clinical presentations of Carrión’s disease suggest complex adaptations by the bacterium to the human host, with the overall objectives of persistence, maintenance of a reservoir state for vectorial transmission, and immune evasion. These events include a multitude of biochemical and genetic mechanisms involving both bacterial and host proteins. This review focuses on proteins involved in interactions between B. bacilliformis and the human host. Some of them (e.g., flagellin, Brps, IalB, FtsZ, Hbp/Pap31, and other outer membrane proteins) are potential protein antigen candidates for a synthetic vaccine. Cesar Henriquez-Camacho, Palmira Ventosilla, Michael F. Minnick, Joaquim Ruiz, and Ciro Maguiña Copyright © 2015 Cesar Henriquez-Camacho et al. All rights reserved. Correlation between Saliva and Plasma Levels of Endothelin Isoforms ET-1, ET-2, and ET-3 Mon, 20 Apr 2015 06:54:53 +0000 Although saliva endothelins are emerging as valuable noninvasive cardiovascular biomarkers, reports on the relationship between isoforms in saliva and plasma remain scarce. We measured endothelins in concurrent saliva and plasma samples ( males; age 18–63) by HPLC-fluorescence. Results revealed statistically significant positive correlations among all isoforms between saliva and plasma: big endothelin-1 (BET-1, 0.55 ± 0.27 versus 3.35 ± 1.28 pmol/mL; , ), endothelin-1 (ET-1, 0.52 ± 0.21 versus 3.45 ± 1.28 pmol/mL; , ), endothelin-2 (ET-2, 0.21 ± 0.07 versus 1.63 ± 0.66 pmol/mL; , ), and endothelin-3 (ET-3, 0.39 ± 0.19 versus 2.32 ± 1.44 pmol/mL; , ). Correlations of BET-1, ET-1, and ET-3 within each compartment were positive in both plasma () and saliva (), whereas ET-2 was not significantly correlated with other isoforms in either plasma or saliva. For all isoforms, concentrations varied on average fivefold between individuals (90th/10th percentiles); individuals with high plasma endothelin levels generally had high saliva endothelin levels. Our results reveal that salivary ET isoform profiles portray the plasmatic profiles and support the view of coordinated regulation of ET-1 and ET-3, but distinct regulatory pathways for ET-2. Roma Gurusankar, Prem Kumarathasan, Anusha Saravanamuthu, Errol M. Thomson, and Renaud Vincent Copyright © 2015 Roma Gurusankar et al. All rights reserved. In Silico Conformational Analysis of the Short-Sequence Hypomurocin A Peptides Wed, 28 Jan 2015 09:43:17 +0000 In this theoretical study, a conformational analysis was performed on short-sequence hypomurocin A peptides, in order to identify their characteristic structural properties. For each hypomurocin A molecule, not only the backbone conformations, but also the side-chain conformations were examined. The results indicated that certain tetrapeptide units could be characterized by types I and III β-turn structures, and considering the helical conformations, it could be concluded that the hypomurocin A peptides showed a preference for the 310-helical structure over the α-helical structure. Beside the backbone conformations, the side-chain conformations were investigated, and the preferred rotamer states of the side-chains of amino acids were determined. Furthermore, the occurrence of and intramolecular H-bonds was studied, which could play a role in the structural stabilization of β-turns and helical conformations. On the whole, our theoretical study supplied a comprehensive characterization of the three-dimensional structure of short-sequence hypomurocin A peptides. Zoltán Násztor, János Horváth, and Balázs Leitgeb Copyright © 2015 Zoltán Násztor et al. All rights reserved. Epithelial Antimicrobial Peptides: Guardian of the Oral Cavity Tue, 11 Nov 2014 07:46:40 +0000 Gingival epithelium provides first line of defence from the microorganisms present in dental plaque. It not only provides a mechanical barrier but also has an active immune function too. Gingival epithelial cells participate in innate immunity by producing a range of antimicrobial peptides to protect the host against oral pathogens. These epithelial antimicrobial peptides (EAPs) include the β-defensin family, cathelicidin (LL-37), calprotectin, and adrenomedullin. While some are constitutively expressed in gingival epithelial cells, others are induced upon exposure to microbial insults. It is likely that these EAPs have a role in determining the initiation and progression of oral diseases. EAPs are broad spectrum antimicrobials with a different but overlapping range of activity. Apart from antimicrobial activity, they participate in several other crucial roles in host tissues. Some of these, for instance, β-defensins, are chemotactic to immune cells. Others, such as calprotectin are important for wound healing and cell proliferation. Adrenomedullin, a multifunctional peptide, has its biological action in a wide range of tissues. Not only is it a potent vasodilator but also it has several endocrine effects. Knowing in detail the various bioactions of these EAPs may provide us with useful information regarding their utility as therapeutic agents. Mayank Hans and Veenu Madaan Hans Copyright © 2014 Mayank Hans and Veenu Madaan Hans. All rights reserved. Cationic Bioactive Peptide from the Seeds of Benincasa hispida Wed, 16 Apr 2014 10:07:35 +0000 A designated bioactive peptide “Hispidalin” purified from the seeds of Benincasa hispida, which is a medicinal plant, belongs to Cucurbitaceae family. Purification was achieved by using a procedure consisting of extraction from potassium phosphate buffer followed by FPLC and HPLC steps. Based on amino acid residue, this peptide is amphipathic and basic with one net positive charge having isoelectric pH 8.1. This peptide is without sulphur containing amino acid suggesting its extended conformation lacking double bond secondary structure. The results obtained from MALDI-TOF suggested that Hispidalin is of molecular mass 5.7 KDa with 49 amino acid residues and confirmed SDS-PAGE resolved ∼6.0 KDa protein band. This novel and unknown peptide “Hispidalin” showed broad and potent inhibitory effects against various human bacterial and fungal pathogens; its growth inhibition was significantly comparable with commercial antibacterial and antifungal drugs. The Hispidalin at 40 μg/mL concentration exhibited 70.8% DPPH free radical-scavenging activity and 69.5% lipid peroxide inhibition. Thus, in the present study, Hispidalin demonstrated remarkable antimicrobial and antioxidant potentials from the seeds of B. hispida. Sunayana Sharma, Hirday Narain Verma, and Nilesh Kumar Sharma Copyright © 2014 Sunayana Sharma et al. All rights reserved. Recombinant Human Trefoil Factor 3 Ameliorates Bowel Injury: Its Anti-Inflammatory Effect on Experimental Necrotizing Enterocolitis Wed, 12 Feb 2014 07:54:49 +0000 Aim. Recombinant human trefoil factor 3 (intestinal trefoil factor) has been suggested to be partially protective against necrotizing enterocolitis (NEC), but the mechanisms of this protection have not been defined. We investigated whether the protective effects of rhTFF3 are the result of an anti-inflammatory response. Methods. The rats were killed on day 4, the distal ileum was harvested for morphological studies and immunohistochemistry for NF-κB (p65), and the amounts of IL-1β, IL-6, and IL-10 in the intestinal tissue were measured using commercial ELISA assay kits. Results. In the neonatal NEC, IL-1β, IL-6, and IL-10 were significantly higher than in normal group. In normal group, IL-1β and IL-6 were significantly decreased, and the amount of IL-10 was markedly increased compared with NEC group. In the NEC model, immunohistochemical staining for NF-κB (p65) was demonstrated to be of a strong brown color and was distributed in the intestinal epithelium. Treatment with rhTFF3 significantly decreased the immunoreactivity of NF-κB (p65) in the NEC model. Conclusions. Intestinal inflammation was ameliorated after rhTFF3 was injected. rhTFF3 may protect against the intestinal injury of the neonatal rat NEC model by suppression of the inflammatory response. Lei Shi, Pang-Hu Zhou, Juan-Li Xi, Hong-Gang Yu, and Bing-Hong Zhang Copyright © 2014 Lei Shi et al. All rights reserved. Structural Features of the Peptide Homologous to 6-25 Fragment of Influenza A PB1 Protein Tue, 24 Dec 2013 18:22:20 +0000 A mirror-symmetry motif was discovered in the N-terminus of the influenza virus PB1 protein. Structure of peptide comprised of the corresponding part of PB1 (amino acid residues 6-25) was investigated by circular dichroism and in silico modeling. We found that peptide PB1 (6-25) in solution assumes beta-hairpin conformation. A truncated peptide PB1 (6-13), containing only half of the mirror-symmetry motif, appeared to stabilize the beta-structure of the original peptide and, at high concentrations, was capable of reacting with peptide to form insoluble aggregates in vitro. Ability of PB1 (6-13) peptide to interact with the N-terminal domain of PB1 protein makes it a potential antiviral agent that inhibits PA-PB1 complex formation by affecting PB1 N-terminus structure. Vladimir V. Egorov, Oleg V. Matusevich, Aram A. Shaldzhyan, Alexey N. Skvortsov, Yana A. Zabrodskaya, Yuri P. Garmay, Sergey B. Landa, Dmitry V. Lebedev, Vladimir V. Zarubayev, Alexey K. Sirotkin, Andrey V. Vasin, and Oleg I. Kiselev Copyright © 2013 Vladimir V. Egorov et al. All rights reserved. A Systematic Review to Investigate Whether Angiotensin-(1-7) Is a Promising Therapeutic Target in Human Heart Failure Thu, 12 Dec 2013 10:45:36 +0000 Context. Heart failure (HF) is a common condition causing much morbidity and mortality despite major advances in pharmacological and device therapies. Preclinical data suggest a cardioprotective role of Angiotensin-(1-7) in animal models of HF. Objective. Perform a systematic review on the effects of Angiotensin-(1-7) on humans, focusing on HF. Results. 39 studies were included in the review (4 in human HF and (35) in non-HF patients). There is only one intervention study on 8 patients with human HF, using Angiotensin-(1-7), with forearm blood flow (FBF) as the endpoint. Angiotensin-(1-7) caused no significant effect on FBF in this HF study but caused vasodilation in 3 out of 4 non-HF studies. In one other non-HF study, Angiotensin-(1-7) infusion led to a significant increase in blood pressure in normal men; however, effects were <0.03% that of angiotensin II. Cardioprotective effects seen in non-HF studies include for instance beneficial actions against atherosclerosis and myocardial fibrosis. Conclusions. The main finding of our systematic review is that Angiotensin-(1-7) plays an important cardioprotective role in HF in animals and in patients without heart failure. More research is required to test the hypothesis that Angiotensin-(1-7) benefits patients with heart failure. Vincent C. H. Lee, Elizabeth N. Lloyd, Helena C. Dearden, and Kenneth Wong Copyright © 2013 Vincent C. H. Lee et al. All rights reserved. Total Chemical Synthesis of a Heterodimeric Interchain Bis-Lactam-Linked Peptide: Application to an Analogue of Human Insulin-Like Peptide 3 Mon, 28 Oct 2013 14:44:41 +0000 Nonreducible cystine isosteres represent important peptide design elements in that they can maintain a near-native tertiary conformation of the peptide while simultaneously extending the in vitro and in vivo half-life of the biomolecule. Examples of these cystine mimics include dicarba, diselenide, thioether, triazole, and lactam bridges. Each has unique physicochemical properties that impact upon the resulting peptide conformation. Each also requires specific conditions for its formation via chemical peptide synthesis protocols. While the preparation of peptides containing two lactam bonds within a peptide is technically possible and reported by others, to date there has been no report of the chemical synthesis of a heterodimeric peptide linked by two lactam bonds. To examine the feasibility of such an assembly, judicious use of a complementary combination of amine and acid protecting groups together with nonfragment-based, total stepwise solid phase peptide synthesis led to the successful preparation of an analogue of the model peptide, insulin-like peptide 3 (INSL3), in which both of the interchain disulfide bonds were replaced with a lactam bond. An analogue containing a single disulfide-substituted interchain lactam bond was also prepared. Both INSL3 analogues retained significant cognate RXFP2 receptor binding affinity. John Karas, Fazel Shabanpoor, Mohammed Akhter Hossain, James Gardiner, Frances Separovic, John D. Wade, and Denis B. Scanlon Copyright © 2013 John Karas et al. All rights reserved. Development of the Schedule for Multiple Parallel “Difficult” Peptide Synthesis on Pins Tue, 20 Aug 2013 10:18:41 +0000 Unified schedule for multiple parallel solid-phase synthesis of so-called “difficult” peptides on polypropylene pins was developed. Increase in the efficiency of 9-fluorenyl(methoxycarbonyl) N-terminal amino-protecting group removal was shown to have a greater influence on the accuracy of the “difficult” peptide synthesis than the use of more efficient amino acid coupling reagents such as aminium salts. Hence the unified schedule for multiple parallel solid-phase synthesis of “difficult” peptides included the procedure for N-terminal amino group deprotection modified by applying a more efficient reagent for the deprotection and the standard procedure of amino acid coupling by carbodiimide method with an additional coupling using aminium salts, if necessary. Amino acid coupling with the help of carbodiimide allows to follow the completeness of the coupling via the bromophenol blue indication, thus providing the accuracy of the synthesis and preventing an overexpenditure of expensive reagents. About 100 biotinylated hepatitis C virus envelope protein fragments, most of which represented “difficult” peptides, were successfully obtained by synthesis on pins with the help of the developed unified schedule. Ekaterina F. Kolesanova, Maxim A. Sanzhakov, and Oleg N. Kharybin Copyright © 2013 Ekaterina F. Kolesanova et al. All rights reserved. Antigenic Peptides Capable of Inducing Specific Antibodies for Detection of the Major Alterations Found in Type 2B Von Willebrand Disease Thu, 18 Jul 2013 14:05:20 +0000 Von Willebrand disease (VWD) is an inherited hemorrhagic disorder promoted by either quantitative or qualitative defects of the von Willebrand factor (VWF). The disease represents the most common human coagulopathy afflicting 1.3% of the population. Qualitative defects are subdivided into four subtypes and classified according to the molecular dysfunction of the VWF. The differential diagnosis of the VWD is a difficult task, relying on a panel of tests aimed to assess the plasma levels and function of the VWF. Here, we propose biochemical approaches for the identification of structural variants of the VWF. A bioinformatic analysis was conducted to design seven peptides among which three were representatives of specific amino acid sequences belonging to normal VWF and four encompassed sequences found in the most common VWD subtype 2B. These peptides were used to immunize mice, after which, peptide-specific immunoglobulins were purified. This resulted in four Ig preparations capable of detecting alterations in the subtype 2B VWD plus additional three antibody fractions targeting the normal VWF. The panel of antibodies could serve many applications among them (1) assessment of VWF: antigen interaction, (2) VWF multimer analysis, and (3) production of monoclonal antibodies against VWF for therapeutic purposes as in thrombotic thrombocytopenic purpura. Marina de Oliveira Paro, Cyntia Silva Ferreira, Fernanda Silva Vieira, Marcos Aurélio de Santana, William Castro-Borges, Maria Sueli Silva Namen-Lopes, Sophie Yvette Leclercq, Cibele Velloso-Rodrigues, and Milton Hércules Guerra de Andrade Copyright © 2013 Marina de Oliveira Paro et al. All rights reserved. High-Throughput Peptide Epitope Mapping Using Carbon Nanotube Field-Effect Transistors Sun, 14 Jul 2013 10:38:40 +0000 Label-free and real-time detection technologies can dramatically reduce the time and cost of pharmaceutical testing and development. However, to reach their full promise, these technologies need to be adaptable to high-throughput automation. To demonstrate the potential of single-walled carbon nanotube field-effect transistors (SWCNT-FETs) for high-throughput peptide-based assays, we have designed circuits arranged in an 8 × 12 (96-well) format that are accessible to standard multichannel pipettors. We performed epitope mapping of two HIV-1 gp160 antibodies using an overlapping gp160 15-mer peptide library coated onto nonfunctionalized SWCNTs. The 15-mer peptides did not require a linker to adhere to the non-functionalized SWCNTs, and binding data was obtained in real time for all 96 circuits. Despite some sequence differences in the HIV strains used to generate these antibodies and the overlapping peptide library, respectively, our results using these antibodies are in good agreement with known data, indicating that peptides immobilized onto SWCNT are accessible and that linear epitope mapping can be performed in minutes using SWCNT-FET. Steingrimur Stefansson, Martha Knight, Hena H. Kwon, Lára A. Stefansson, and Saeyoung Nate Ahn Copyright © 2013 Steingrimur Stefansson et al. All rights reserved. Antimicrobial Peptides: Versatile Biological Properties Wed, 26 Jun 2013 11:36:29 +0000 Antimicrobial peptides are diverse group of biologically active molecules with multidimensional properties. In recent past, a wide variety of AMPs with diverse structures have been reported from different sources such as plants, animals, mammals, and microorganisms. The presence of unusual amino acids and structural motifs in AMPs confers unique structural properties to the peptide that attribute for their specific mode of action. The ability of these active AMPs to act as multifunctional effector molecules such as signalling molecule, immune modulators, mitogen, antitumor, and contraceptive agent makes it an interesting candidate to study every aspect of their structural and biological properties for prophylactic and therapeutic applications. In addition, easy cloning and recombinant expression of AMPs in heterologous plant host systems provided a pipeline for production of disease resistant transgenic plants. Besides these properties, AMPs were also used as drug delivery vectors to deliver cell impermeable drugs to cell interior. The present review focuses on the diversity and broad spectrum antimicrobial activity of AMPs along with its multidimensional properties that could be exploited for the application of these bioactive peptides as a potential and promising drug candidate in pharmaceutical industries. Muthuirulan Pushpanathan, Paramasamy Gunasekaran, and Jeyaprakash Rajendhran Copyright © 2013 Muthuirulan Pushpanathan et al. All rights reserved. Amyloid Beta Peptides Differentially Affect Hippocampal Theta Rhythms In Vitro Tue, 25 Jun 2013 18:29:42 +0000 Soluble amyloid beta peptide (Aβ) is responsible for the early cognitive dysfunction observed in Alzheimer's disease. Both cholinergically and glutamatergically induced hippocampal theta rhythms are related to learning and memory, spatial navigation, and spatial memory. However, these two types of theta rhythms are not identical; they are associated with different behaviors and can be differentially modulated by diverse experimental conditions. Therefore, in this study, we aimed to investigate whether or not application of soluble Aβ alters the two types of theta frequency oscillatory network activity generated in rat hippocampal slices by application of the cholinergic and glutamatergic agonists carbachol or DHPG, respectively. Due to previous evidence that oscillatory activity can be differentially affected by different Aβ peptides, we also compared and for their effects on theta rhythms in vitro at similar concentrations (0.5 to 1.0 μM). We found that reduces, with less potency than , carbachol-induced population theta oscillatory activity. In contrast, DHPG-induced oscillatory activity was not affected by a high concentration of but was reduced by . Our results support the idea that different amyloid peptides might alter specific cellular mechanisms related to the generation of specific neuronal network activities, instead of exerting a generalized inhibitory effect on neuronal network function. Armando I. Gutiérrez-Lerma, Benito Ordaz, and Fernando Peña-Ortega Copyright © 2013 Armando I. Gutiérrez-Lerma et al. All rights reserved. Nociceptin Signaling Involves a Calcium-Based Depolarization in Tetrahymena thermophila Mon, 29 Apr 2013 08:59:34 +0000 Tetrahymena thermophila are free-living, ciliated eukaryotes. Their behavioral response to stimuli is well characterized and easily observable, since cells swim toward chemoattractants and avoid chemorepellents. Chemoattractant responses involve increased swim speed or a decreased change in swim direction, while chemorepellent signaling involves ciliary reversal, which causes the organism to jerk back and forth, swim in small circles, or spin in an attempt to get away from the repellent. Many food sources, such as proteins, are chemoattractants for these organisms, while a variety of compounds are repellents. Repellents in nature are thought to come from the secretions of predators or from ruptured organisms, which may serve as “danger” signals. Interestingly, several peptides involved in vertebrate pain signaling are chemorepellents in Tetrahymena, including substances P, ACTH, PACAP, VIP, and nociceptin. Here, we characterize the response of Tetrahymena thermophila to three different isoforms of nociceptin. We find that G-protein inhibitors and tyrosine kinase inhibitors do not affect nociceptin avoidance. However, the calcium chelator, EGTA, and the SERCA calcium ATPase inhibitor, thapsigargin, both inhibit nociceptin avoidance, implicating calcium in avoidance. This result is confirmed by electrophysiology studies which show that 50 M nociceptin-NH2 causes a sustained depolarization of approximately 40 mV, which is eliminated by the addition of extracellular EGTA. Thomas Lampert, Cheryl Nugent, John Weston, Nathanael Braun, and Heather Kuruvilla Copyright © 2013 Thomas Lampert et al. All rights reserved. Interaction between Pirenzepine and Ninjinto, a Traditional Japanese Herbal Medicine, on the Plasma Gut-Regulated Peptide Levels in Humans Wed, 27 Mar 2013 14:56:00 +0000 The Japanese herbal medicine (Kampo) Ninjinto has been used for the treatment of gastroenteritis, esogastritis, gastric atony, gastrectasis, vomiting, and anorexia. The pharmacological effects of Ninjinto on the gastrointestine are due to changes in the levels of gut-regulated peptide, such as motilin, somatostatin, calcitonin gene-related peptide (CGRP), substance P, and vasoactive intestinal polypeptide (VIP). The release of these peptides is controlled by acetylcholine (ACh) from the preganglionic fibers of the parasympathetic nerve. Thus, we examined the effects of the selective M1 muscarinic receptor antagonist pirenzepine on the elevation of Ninjinto-induced plasma the area under the plasma gut-regulated peptide concentration-time curve from 0 to 240 min () in humans. Oral pretreatment with pirenzepine significantly reduced the Ninjinto-induced elevation of plasma motilin and substance P release (). Combined treatment with Ninjinto and pirenzepine significantly increased the release of plasma somatostatin () compared with administration of Ninjinto alone or placebo. Ninjinto appeared to induce the release of substance P and motilin into plasma mainly through the activation of M1 muscarinic receptors, and pirenzepine may affect the pharmacologic action of Ninjinto by the elevation of plasma substance P, motilin, and somatostatin. Yuhki Sato, Itoh Hiroki, Yosuke Suzuki, Ryosuke Tatsuta, and Masaharu Takeyama Copyright © 2013 Yuhki Sato et al. All rights reserved. Significant Increase in Salivary Substance P Level after a Single Oral Dose of Cevimeline in Humans Sun, 24 Mar 2013 11:51:57 +0000 Cevimeline is a novel muscarinic acetylcholine receptor agonist currently being developed as a therapeutic agent for xerostomia. We examined the effects of cevimeline on salivary and plasma levels of substance-P- (SP-), calcitonin-gene-related-peptide- (CGRP-), and vasoactive-intestinal-polypeptide- (VIP-) like immunoreactive substances (ISs) in humans. An open-labeled crossover study was conducted on seven healthy volunteers. Saliva volume was measured, and saliva and venous blood samples were collected before and 30–240 min after a single oral dose of cevimeline or placebo. Salivary and plasma levels of SP-, CGRP-, and VIP-IS were measured using a highly sensitive enzyme immunoassay. A single oral dose of cevimeline resulted in significant increases in salivary but not plasma SP-IS level compared to placebo. Cevimeline administration did not alter the salivary or plasma levels of CGRP-IS or VIP-IS compared to placebo. Significant increases in salivary volume were observed after cevimeline administration compared to placebo. A significant correlation was observed between the total release of SP-IS and that of salivary volume. These findings suggest an association of SP with the enhancement of salivary secretion by cevimeline. Yosuke Suzuki, Hiroki Itoh, Kohei Amada, Ryota Yamamura, Yuhki Sato, and Masaharu Takeyama Copyright © 2013 Yosuke Suzuki et al. All rights reserved. Antimicrobial Lactoferrin Peptides: The Hidden Players in the Protective Function of a Multifunctional Protein Sun, 10 Mar 2013 13:40:07 +0000 Lactoferrin is a multifunctional, iron-binding glycoprotein which displays a wide array of modes of action to execute its primary antimicrobial function. It contains various antimicrobial peptides which are released upon its hydrolysis by proteases. These peptides display a similarity with the antimicrobial cationic peptides found in nature. In the current scenario of increasing resistance to antibiotics, there is a need for the discovery of novel antimicrobial drugs. In this context, the structural and functional perspectives on some of the antimicrobial peptides found in N-lobe of lactoferrin have been reviewed. This paper provides the comparison of lactoferrin peptides with other antimicrobial peptides found in nature as well as interspecies comparison of the structural properties of these peptides within the native lactoferrin. Mau Sinha, Sanket Kaushik, Punit Kaur, Sujata Sharma, and Tej P. Singh Copyright © 2013 Mau Sinha et al. All rights reserved. Systemic Ghrelin Administration Alters Serum Biomarkers of Angiogenesis in Diet-Induced Obese Mice Thu, 28 Feb 2013 09:38:18 +0000 Introduction. Ghrelin is a gastrointestinal endocrine peptide that was initially identified as the endogenous ligand of growth hormone secretagogue receptor; however, recently, the cardiovascular effect of this peptide has been indicated. In this study, we investigated the effect of ghrelin administration on serum biomarkers of angiogenesis including leptin, nitric oxide (NO), vascular endothelial growth factor (VEGF), and its soluble receptor (VEGF receptor 1 or sFlt-1) in control- and diet-induced obese mice. Methods. Male C57BL/6 mice were randomly divided into four groups, normal diet (ND) or control, ND + ghrelin, high-fat-diet (HFD) or obese and HFD + ghrelin (/group). Obese and control groups received either HFD or ND for 15 weeks. Then, the ghrelin was injected subcutaneously 100 µg/kg twice daily for 10 days. At the end of experiment, blood samples were collected for blood glucose, serum insulin, VEGF, sFlt-1, NO, and leptin measurements. Results. The obese animals had higher serum NO and leptin concentrations without changes in serum VEGF and sFlt-1 levels compared to control. Administration of ghrelin significantly increased serum VEGF and decreased serum leptin and NO concentrations in HFD group. Conclusion. Since ghrelin changes serum biomarkers of angiogenesis, it seems that it gets involved during states with abnormal angiogenesis. M. Khazaei and Z. Tahergorabi Copyright © 2013 M. Khazaei and Z. Tahergorabi. All rights reserved. α-RgIB: A Novel Antagonist Peptide of Neuronal Acetylcholine Receptor Isolated from Conus regius Venom Wed, 27 Feb 2013 17:54:19 +0000 Conus venoms are rich sources of biologically active peptides that act specifically on ionic channels and metabotropic receptors present at the neuromuscular junction, efficiently paralyzing the prey. Each species of Conus may have 50 to 200 uncharacterized bioactive peptides with pharmacological interest. Conus regius is a vermivorous species that inhabits Northeastern Brazilian tropical waters. In this work, we characterized one peptide with activity on neuronal acetylcholine receptor (nAChR). Crude venom was purified by reverse-phase HPLC and selected fractions were screened and sequenced by mass spectrometry, MALDI-ToF, and ESI-Q-ToF, respectively. A new peptide was identified, bearing two disulfide bridges. The novel 2,701 Da peptide belongs to the cysteine framework I, corresponding to the cysteine pattern CC-C-C. The biological activity of the purified peptide was tested by intracranial injection in mice, and it was observed that high concentrations induced hyperactivity in the animals, whereas lower doses caused breathing difficulty. The activity of this peptide was assayed in patch-clamp experiments, on nAChR-rich cells, in whole-cell configuration. The peptide blocked slow rise-time neuronal receptors, probably α3β4 and/or α3β4α5 subtype. According to the nomenclature, the new peptide was designated as α-RgIB. Maria Cristina Vianna Braga, Arthur Andrade Nery, Henning Ulrich, Katsuhiro Konno, Juliana Mozer Sciani, and Daniel Carvalho Pimenta Copyright © 2013 Maria Cristina Vianna Braga et al. All rights reserved. Phage Display Screening for Tumor Necrosis Factor-α-Binding Peptides: Detection of Inflammation in a Mouse Model of Hepatitis Tue, 26 Feb 2013 15:50:41 +0000 TNF-α is one of the most abundant cytokines produced in many inflammatory and autoimmune conditions such as multiple sclerosis, chronic hepatitis C, or neurodegenerative diseases. These pathologies remain difficult to diagnose and consequently difficult to treat. The aim of this work is to offer a new diagnostic tool by seeking new molecular probes for medical imaging. The target-specific part of the probe consists here of heptameric peptides selected by the phage display technology for their affinity for TNF-α. Several affinity tests allowed isolating 2 peptides that showed the best binding capacity to TNF-α. Finally, the best peptide was synthesized in both linear and cyclic forms and tested on the histological sections of concanavalin-A-(ConA-)treated mice liver. In this well-known hepatitis mouse model, the best results were obtained with the cyclic form of peptide 2, which allowed for the staining of inflamed areas in the liver. The cyclic form of peptide 2 (2C) was, thus, covalently linked to iron oxide nanoparticles (magnetic resonance imaging (MRI) contrast agent) and tested in the ConA-induced hepatitis mouse model. The vectorized nanoparticles allowed for the detection of inflammation as well as of the free peptide. These ex vivo results suggest that phage display-selected peptides can direct imaging contrast agents to inflammatory areas. Coralie Sclavons, Carmen Burtea, Sébastien Boutry, Sophie Laurent, Luce Vander Elst, and Robert N. Muller Copyright © 2013 Coralie Sclavons et al. All rights reserved. Sequence Determination of a Novel Tripeptide Isolated from the Young Leaves of Azadirachta indica A. Juss Wed, 20 Feb 2013 10:10:47 +0000 The neem tree has long been recognized for its unique properties, both against insects and in improving human health. Every part of the tree has been used as a traditional medicine for household remedy against various human ailments, from antiquity. Although the occurrence of various phytochemicals in neem has been studied, we have identified the presence of a novel tripeptide in the young leaves of neem using a simple and inexpensive paper chromatographic method, detected by Cu(II)-ninhydrin reagent. The peptide nature of the isolated compound is confirmed by spectral studies. The sequence of the peptide is determined using de novo sequencing by tandem MS after purification. M. Rajeswari Prabha and B. Ramachandramurty Copyright © 2013 M. Rajeswari Prabha and B. Ramachandramurty. All rights reserved. Peptide Receptor Targeting in Cancer: The Somatostatin Paradigm Thu, 07 Feb 2013 12:00:29 +0000 Peptide receptors involved in pathophysiological processes represent promising therapeutic targets. Neuropeptide somatostatin (SST) is produced by specialized cells in a large number of human organs and tissues. SST primarily acts as inhibitor of endocrine and exocrine secretion via the activation of five G-protein-coupled receptors, named sst1–5, while in central nervous system, SST acts as a neurotransmitter/neuromodulator, regulating locomotory and cognitive functions. Critical points of SST/SST receptor biology, such as signaling pathways of individual receptor subtypes, homo- and heterodimerization, trafficking, and cross-talk with growth factor receptors, have been extensively studied, although functions associated with several pathological conditions, including cancer, are still not completely unraveled. Importantly, SST exerts antiproliferative and antiangiogenic effects on cancer cells in vitro, and on experimental tumors in vivo. Moreover, SST agonists are clinically effective as antitumor agents for pituitary adenomas and gastro-pancreatic neuroendocrine tumors. However, SST receptors being expressed by tumor cells of various tumor histotypes, their pharmacological use is potentially extendible to other cancer types, although to date no significant results have been obtained. In this paper the most recent findings on the expression and functional roles of SST and SST receptors in tumor cells are discussed. Federica Barbieri, Adriana Bajetto, Alessandra Pattarozzi, Monica Gatti, Roberto Würth, Stefano Thellung, Alessandro Corsaro, Valentina Villa, Mario Nizzari, and Tullio Florio Copyright © 2013 Federica Barbieri et al. All rights reserved. Identification and Characterization of a Novel Nontranslated Sequence Variant of the Human Intestinal Di-/Tripeptide Transporter, hPEPT1 Sun, 30 Dec 2012 08:47:01 +0000 The human H+-coupled di-/tripeptide transporter (hPEPT1) mediates intestinal absorption of dietary di- and tripeptides, as well as several peptidomimetic drug compounds. The aim of the present study was to investigate the possible role of the hPEPT1 variant hPEPT1-RF in hPEPT1 regulation. However, the proposed hPEPT1-RF mRNA sequence could not be detected in Caco-2 cells or in human intestinal samples. Instead, a new sequence variant, hPEPT1-RFI, was found, which is almost identical to the proposed hPEPT1-RF, except for two nucleotide insertions and one deletion that resulted in a changed open reading frame as compared to hPEPT1-RF. In vitro translation analysis showed that hPEPT1-RFI was not translated. In conclusion, the existence of hPEPT1-RF could not be confirmed; furthermore, the identified sequence variant, hPEPT1-RFI, does not appear to be translated and is therefore unlikely to have a regulatory effect on hPEPT1 transport activity. Helle Bach Søndergaard, Carsten Uhd Nielsen, and Birger Brodin Copyright © 2012 Helle Bach Søndergaard et al. All rights reserved. Erratum to “Characterization of Selective Antibacterial Peptides by Polarity Index” Mon, 24 Dec 2012 09:16:47 +0000 C. Polanco, J. L. Samaniego, T. Buhse, F. G. Mosqueira, A. Negron-Mendoza, S. Ramos-Bernal, and J. A. Castanon-Gonzalez Copyright © 2012 C. Polanco et al. All rights reserved.