Glucagon-like peptide-1 receptor agonists and risk of acute pancreatitis in patients with type 2 diabetes

DEFF Research Database (Denmark)

Storgaard, Heidi; Cold, Frederik; Gluud, Lise L

2017-01-01

Glucagon-like peptide-1 receptor agonist (GLP-1RAs) labels warn about acute pancreatitis (AP) and impose upon doctors the obligation to inform patients about symptoms of AP. Here we systematically reviewed the risk of AP in randomized placebo-controlled trials (RCTs) investigating the effect of GLP...

Exhaustive search of linear information encoding protein-peptide recognition.

Science.gov (United States)

Kelil, Abdellali; Dubreuil, Benjamin; Levy, Emmanuel D; Michnick, Stephen W

2017-04-01

High-throughput in vitro methods have been extensively applied to identify linear information that encodes peptide recognition. However, these methods are limited in number of peptides, sequence variation, and length of peptides that can be explored, and often produce solutions that are not found in the cell. Despite the large number of methods developed to attempt addressing these issues, the exhaustive search of linear information encoding protein-peptide recognition has been so far physically unfeasible. Here, we describe a strategy, called DALEL, for the exhaustive search of linear sequence information encoded in proteins that bind to a common partner. We applied DALEL to explore binding specificity of SH3 domains in the budding yeast Saccharomyces cerevisiae. Using only the polypeptide sequences of SH3 domain binding proteins, we succeeded in identifying the majority of known SH3 binding sites previously discovered either in vitro or in vivo. Moreover, we discovered a number of sites with both non-canonical sequences and distinct properties that may serve ancillary roles in peptide recognition. We compared DALEL to a variety of state-of-the-art algorithms in the blind identification of known binding sites of the human Grb2 SH3 domain. We also benchmarked DALEL on curated biological motifs derived from the ELM database to evaluate the effect of increasing/decreasing the enrichment of the motifs. Our strategy can be applied in conjunction with experimental data of proteins interacting with a common partner to identify binding sites among them. Yet, our strategy can also be applied to any group of proteins of interest to identify enriched linear motifs or to exhaustively explore the space of linear information encoded in a polypeptide sequence. Finally, we have developed a webserver located at http://michnick.bcm.umontreal.ca/dalel, offering user-friendly interface and providing different scenarios utilizing DALEL.

Design of ET(B) receptor agonists: NMR spectroscopic and conformational studies of ET7-21[Leu7, Aib11, Cys(Acm)15].

Science.gov (United States)

Hewage, Chandralal M; Jiang, Lu; Parkinson, John A; Ramage, Robert; Sadler, Ian H

2002-03-01

In a previous report we have shown that the endothelin-B receptor-selective linear endothelin peptide, ET-1[Cys (Acm)1,15, Ala3, Leu7, Aib11], folds into an alpha-helical conformation in a methanol-d3/water co-solvent [Hewage et al. (1998) FEBS Lett., 425, 234-238]. To study the requirements for the structure-activity relationships, truncated analogues of this peptide were subjected to further studies. Here we report the solution conformation of ET7-21[Leu7, Aib11, Cys(Acm)15], in a methanol-d3/water co-solvent at pH 3.6, by NMR spectroscopic and molecular modelling studies. Further truncation of this short peptide results in it displaying poor agonist activity. The modelled structure shows that the peptide folds into an alpha-helical conformation between residues Lys9-His16, whereas the C-terminus prefers no fixed conformation. This truncated linear endothelin analogue is pivotal for designing endothelin-B receptor agonists.

Annotating and Interpreting Linear and Cyclic Peptide Tandem Mass Spectra.

Science.gov (United States)

Niedermeyer, Timo Horst Johannes

2016-01-01

Nonribosomal peptides often possess pronounced bioactivity, and thus, they are often interesting hit compounds in natural product-based drug discovery programs. Their mass spectrometric characterization is difficult due to the predominant occurrence of non-proteinogenic monomers and, especially in the case of cyclic peptides, the complex fragmentation patterns observed. This makes nonribosomal peptide tandem mass spectra annotation challenging and time-consuming. To meet this challenge, software tools for this task have been developed. In this chapter, the workflow for using the software mMass for the annotation of experimentally obtained peptide tandem mass spectra is described. mMass is freely available (http://www.mmass.org), open-source, and the most advanced and user-friendly software tool for this purpose. The software enables the analyst to concisely annotate and interpret tandem mass spectra of linear and cyclic peptides. Thus, it is highly useful for accelerating the structure confirmation and elucidation of cyclic as well as linear peptides and depsipeptides.

Glucagon-like peptide-1 receptor agonists for the treatment of type 2 diabetes

DEFF Research Database (Denmark)

Lund, Asger; Knop, Filip K; Vilsbøll, Tina

2014-01-01

Glucagon-like peptide-1 (GLP-1) is a gastrointestinal hormone, secreted in response to ingestion of nutrients, and has important effects on several of the pathophysiological features of type 2 diabetes (T2D). The effects include potentiation of insulin secretion, suppression of glucagon secretion...... effects. This review gives an overview of the clinical data on GLP-1R agonists that have been compared in head-to-head studies and focuses on relevant differences between the compounds. Highlighting these similarities and differences could be beneficial for physicians in choosing the best treatment......, slowing of gastric emptying and suppression of appetite. In circulation, GLP-1 has a half-life of approximately 2min due to rapid degradation by the enzyme dipeptidyl peptidase 4 (DPP-4). Because of this short half-life GLP-1 receptor (GLP-1R) agonists, resistant to degradation by DPP-4 have been...

Ghrelin receptor inverse agonists: identification of an active peptide core and its interaction epitopes on the receptor

DEFF Research Database (Denmark)

Holst, Birgitte; Lang, Manja; Brandt, Erik

2006-01-01

[D-Arg1,D-Phe5,D-Trp7,9,Leu11]Substance P functions as a low-potency antagonist but a high-potency full inverse agonist on the ghrelin receptor. Through a systematic deletion and substitution analysis of this peptide, the C-terminal carboxyamidated pentapeptide wFwLX was identified as the core...... structure, which itself displayed relatively low inverse agonist potency. Mutational analysis at 17 selected positions in the main ligand-binding crevice of the ghrelin receptor demonstrated that ghrelin apparently interacts only with residues in the middle part of the pocket [i.e., between transmembrane...... upon both AspII:20 and GluIII:09. The identified pharmacophore can possibly serve as the basis for targeted discovery of also nonpeptide inverse agonists for the ghrelin receptor....

Comparison Review of Short-Acting and Long-Acting Glucagon-like Peptide-1 Receptor Agonists

OpenAIRE

Uccellatore, Annachiara; Genovese, Stefano; Dicembrini, Ilaria; Mannucci, Edoardo; Ceriello, Antonio

2015-01-01

Glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1 RAs) are useful tools for treating type 2 diabetes mellitus. In their recent position statement, the American Diabetes Association and European Association for the Study of Diabetes recommend GLP1-RAs as add-on to metformin when therapeutic goals are not achieved with monotherapy, particularly for patients who wish to avoid weight gain or hypoglycemia. GLP1-RAs differ substantially in their duration of action, frequency of administratio...

Exendin-4, a glucagon-like peptide-1 receptor agonist, reduces intimal thickening after vascular injury

Energy Technology Data Exchange (ETDEWEB)

Goto, Hiromasa [Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Nomiyama, Takashi, E-mail: tnomiyama@fukuoka-u.ac.jp [Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Mita, Tomoya; Yasunari, Eisuke; Azuma, Kosuke; Komiya, Koji; Arakawa, Masayuki; Jin, Wen Long; Kanazawa, Akio [Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Kawamori, Ryuzo [Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Sportology Center, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Center for Therapeutic Innovations in Diabetes, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Center for Beta Cell Biology and Regeneration, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Fujitani, Yoshio; Hirose, Takahisa [Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Center for Therapeutic Innovations in Diabetes, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Watada, Hirotaka, E-mail: hwatada@juntendo.ac.jp [Department of Medicine, Metabolism and Endocrinology, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan); Sportology Center, Juntendo University Graduate School of Medicine, Tokyo 113-8421 (Japan)

2011-02-04

Research highlights: {yields} Exendin-4 reduces neointimal formation after vascular injury in a mouse model. {yields} Exendin-4 dose not alter metabolic parameters in non-diabetic, non-obese mouse model. {yields} Exendin-4 reduces PDGF-induced cell proliferation in cultured SMCs. {yields} Exendin-4 may reduces neointimal formation after vascular injury at least in part through its direct action on SMCs. -- Abstract: Glucagon-like peptide-1 is a hormone secreted by L cells of the small intestine and stimulates glucose-dependent insulin response. Glucagon-like peptide-1 receptor agonists such as exendin-4 are currently used in type 2 diabetes, and considered to have beneficial effects on the cardiovascular system. To further elucidate the effect of glucagon-like peptide-1 receptor agonists on cardiovascular diseases, we investigated the effects of exendin-4 on intimal thickening after endothelial injury. Under continuous infusion of exendin-4 at 24 nmol/kg/day, C57BL/6 mice were subjected to endothelial denudation injury of the femoral artery. Treatment of mice with exendin-4 reduced neointimal formation at 4 weeks after arterial injury without altering body weight or various metabolic parameters. In addition, in vitro studies of isolated murine, rat and human aortic vascular smooth muscle cells showed the expression of GLP-1 receptor. The addition of 10 nM exendin-4 to cultured smooth muscle cells significantly reduced their proliferation induced by platelet-derived growth factor. Our results suggested that exendin-4 reduced intimal thickening after vascular injury at least in part by the suppression of platelet-derived growth factor-induced smooth muscle cells proliferation.

Exendin-4, a glucagon-like peptide-1 receptor agonist, reduces intimal thickening after vascular injury

International Nuclear Information System (INIS)

Goto, Hiromasa; Nomiyama, Takashi; Mita, Tomoya; Yasunari, Eisuke; Azuma, Kosuke; Komiya, Koji; Arakawa, Masayuki; Jin, Wen Long; Kanazawa, Akio; Kawamori, Ryuzo; Fujitani, Yoshio; Hirose, Takahisa; Watada, Hirotaka

2011-01-01

Research highlights: → Exendin-4 reduces neointimal formation after vascular injury in a mouse model. → Exendin-4 dose not alter metabolic parameters in non-diabetic, non-obese mouse model. → Exendin-4 reduces PDGF-induced cell proliferation in cultured SMCs. → Exendin-4 may reduces neointimal formation after vascular injury at least in part through its direct action on SMCs. -- Abstract: Glucagon-like peptide-1 is a hormone secreted by L cells of the small intestine and stimulates glucose-dependent insulin response. Glucagon-like peptide-1 receptor agonists such as exendin-4 are currently used in type 2 diabetes, and considered to have beneficial effects on the cardiovascular system. To further elucidate the effect of glucagon-like peptide-1 receptor agonists on cardiovascular diseases, we investigated the effects of exendin-4 on intimal thickening after endothelial injury. Under continuous infusion of exendin-4 at 24 nmol/kg/day, C57BL/6 mice were subjected to endothelial denudation injury of the femoral artery. Treatment of mice with exendin-4 reduced neointimal formation at 4 weeks after arterial injury without altering body weight or various metabolic parameters. In addition, in vitro studies of isolated murine, rat and human aortic vascular smooth muscle cells showed the expression of GLP-1 receptor. The addition of 10 nM exendin-4 to cultured smooth muscle cells significantly reduced their proliferation induced by platelet-derived growth factor. Our results suggested that exendin-4 reduced intimal thickening after vascular injury at least in part by the suppression of platelet-derived growth factor-induced smooth muscle cells proliferation.

Development of second generation peptides modulating cellular adiponectin receptor responses

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Laszlo eOtvos

2014-10-01

Full Text Available The adipose tissue participates in the regulation of energy homeostasis as an important endocrine organ that secretes a number of biologically active adipokines, including adiponectin. Recently we developed and characterized a first-in-class peptide-based adiponectin receptor agonist by using in vitro and in vivo models of glioblastoma and breast cancer (BC. In the current study, we further explored the effects of peptide ADP355 in additional cellular models and found that ADP355 inhibited chronic myeloid leukemia (CML cell proliferation and renal myofibroblast differentiation with mid-nanomolar IC50 values. According to molecular modeling calculations, ADP355 was remarkably flexible in the global minimum with a turn present in the middle of the peptide. Considering these structural features of ADP355 and the fact that adiponectin normally circulates as multimeric complexes, we developed and tested the activity of a linear branched dimer (ADP399. The dimer exhibited approximately 20-fold improved cellular activity inhibiting K562 CML and MCF-7 cell growth with high pM - low nM relative IC50 values. Biodistribution studies suggested superior tissue dissemination of both peptides after subcutaneous administration relative to intraperitoneal inoculation. After screening of a 397-member adiponectin active site library, a novel octapeptide (ADP400 was designed that counteracted 10-1000 nM ADP355- and ADP399-mediated effects on CML and BC cell growth at nanomolar concentrations. ADP400 induced mitogenic effects in MCF-7 BC cells perhaps due to antagonizing endogenous adiponectin actions or acting as an inverse agonist. While the linear dimer agonist ADP399 meets pharmacological criteria of a contemporary peptide drug lead, the peptide showing antagonist activity (ADP400 at similar concentrations will be an important target validation tool to study adiponectin functions.

Development of second generation peptides modulating cellular adiponectin receptor responses

Science.gov (United States)

Otvos, Laszlo; Knappe, Daniel; Hoffmann, Ralf; Kovalszky, Ilona; Olah, Julia; Hewitson, Tim; Stawikowska, Roma; Stawikowski, Maciej; Cudic, Predrag; Lin, Feng; Wade, John; Surmacz, Eva; Lovas, Sandor

2014-10-01

The adipose tissue participates in the regulation of energy homeostasis as an important endocrine organ that secretes a number of biologically active adipokines, including adiponectin. Recently we developed and characterized a first-in-class peptide-based adiponectin receptor agonist by using in vitro and in vivo models of glioblastoma and breast cancer (BC). In the current study, we further explored the effects of peptide ADP355 in additional cellular models and found that ADP355 inhibited chronic myeloid leukemia (CML) cell proliferation and renal myofibroblast differentiation with mid-nanomolar IC50 values. According to molecular modeling calculations, ADP355 was remarkably flexible in the global minimum with a turn present in the middle of the peptide. Considering these structural features of ADP355 and the fact that adiponectin normally circulates as multimeric complexes, we developed and tested the activity of a linear branched dimer (ADP399). The dimer exhibited approximately 20-fold improved cellular activity inhibiting K562 CML and MCF-7 cell growth with high pM - low nM relative IC50 values. Biodistribution studies suggested superior tissue dissemination of both peptides after subcutaneous administration relative to intraperitoneal inoculation. After screening of a 397-member adiponectin active site library, a novel octapeptide (ADP400) was designed that counteracted 10-1000 nM ADP355- and ADP399-mediated effects on CML and BC cell growth at nanomolar concentrations. ADP400 induced mitogenic effects in MCF-7 BC cells perhaps due to antagonizing endogenous adiponectin actions or acting as an inverse agonist. While the linear dimer agonist ADP399 meets pharmacological criteria of a contemporary peptide drug lead, the peptide showing antagonist activity (ADP400) at similar concentrations will be an important target validation tool to study adiponectin functions.

Characterization of melanocortin NDP-MSH agonist peptide fragments at the mouse central and peripheral melanocortin receptors.

Science.gov (United States)

Haskell-Luevano, C; Holder, J R; Monck, E K; Bauzo, R M

2001-06-21

The central melanocortin receptors, melanocortin-4 (MC4R) and melanocortin-3 (MC3R), are involved in the regulation of satiety and energy homeostasis. The MC4R in particular has become a pharmaceutical industry drug target due to its direct involvement in the regulation of food intake and its potential therapeutic application for the treatment of obesity-related diseases. The melanocortin receptors are stimulated by the native ligand, alpha-melanocyte stimulating hormone (alpha-MSH). The potent and enzymatically stable analogue NDP-MSH (Ac-Ser-Tyr-Ser-Nle-Glu-His-DPhe-Arg-Trp-Gly-Lys-Pro-Val-NH(2)) is a lead peptide for the identification of melanocortin amino acids important for receptor molecular recognition and stimulation. We have synthesized nine peptide fragments of NDP-MSH, deleting N- and C-terminal amino acids to determine the "minimally active" sequence of NDP-MSH. Additionally, five peptides were synthesized to study stereochemical inversion at the Phe 7 and Trp 9 positions in attempts to increase tetra- and tripeptide potencies. These peptide analogues were pharmacologically characterized at the mouse melanocortin MC1, MC3, MC4, and MC5 receptors. This study has identified the Ac-His-DPhe-Arg-Trp-NH(2) tetrapeptide as possessing 10 nM agonist activity at the brain MC4R. The tripeptide Ac-DPhe-Arg-Trp-NH(2) possessed micromolar agonist activities at the MC1R, MC4R, and MC5R but only slight stimulatory activity was observed at the MC3R (at up to 100 microM concentration). This study has also examined to importance of both N- and C-terminal NDP-MSH amino acids at the different melanocortin receptors, providing information for drug design and identification of putative ligand-receptor interactions.

Click-Chemistry-Mediated Synthesis of Selective Melanocortin Receptor 4 Agonists

DEFF Research Database (Denmark)

Palmer, Daniel; Gonçalves, Juliana P.L.; Hansen, Louise V.

2017-01-01

The melanocortin receptor 4 (MC4R) subtype of the melanocortin receptor family is a target for therapeutics to ameliorate metabolic dysfunction. Endogenous MC4R agonists possess a critical pharmacophore (HFRW), and cyclization of peptide agonists often enhances potency. Thus, 17 cyclized peptides...

High-resolution mapping of linear antibody epitopes using ultrahigh-density peptide microarrays

DEFF Research Database (Denmark)

Buus, Søren; Rockberg, Johan; Forsström, Björn

2012-01-01

Antibodies empower numerous important scientific, clinical, diagnostic, and industrial applications. Ideally, the epitope(s) targeted by an antibody should be identified and characterized, thereby establishing antibody reactivity, highlighting possible cross-reactivities, and perhaps even warning...... against unwanted (e.g. autoimmune) reactivities. Antibodies target proteins as either conformational or linear epitopes. The latter are typically probed with peptides, but the cost of peptide screening programs tends to prohibit comprehensive specificity analysis. To perform high-throughput, high......-resolution mapping of linear antibody epitopes, we have used ultrahigh-density peptide microarrays generating several hundred thousand different peptides per array. Using exhaustive length and substitution analysis, we have successfully examined the specificity of a panel of polyclonal antibodies raised against...

Agonist-induced internalisation of the glucagon-like peptide-1 receptor is mediated by the Gαq pathway.

Science.gov (United States)

Thompson, Aiysha; Kanamarlapudi, Venkateswarlu

2015-01-01

The glucagon-like peptide-1 receptor (GLP-1R) is a G-protein-coupled receptor (GPCR) and an important target in the treatment of type 2 diabetes mellitus (T2DM). Upon stimulation with agonist, the GLP-1R signals through both Gαs and Gαq coupled pathways to stimulate insulin secretion. The agonist-induced GLP-1R internalisation has recently been shown to be important for insulin secretion. However, the molecular mechanisms underlying GLP-1R internalisation remain unknown. The aim of this study was to determine the role of GLP-1R downstream signalling pathways in its internalisation. Agonist-induced human GLP-1R (hGLP-1R) internalisation and activity were examined using a number of techniques including immunoblotting, ELISA, immunofluorescence and luciferase assays to determine cAMP production, intracellular Ca(2+) accumulation and ERK phosphorylation. Agonist-induced hGLP-1R internalisation is dependent on caveolin-1 and dynamin. Inhibition of the Gαq pathway but not the Gαs pathway affected hGLP-1R internalisation. Consistent with this, hGLP-1R mutant T149M and small-molecule agonists (compound 2 and compound B), which activate only the Gαs pathway, failed to induce internalisation of the receptor. Chemical inhibitors of the Gαq pathway, PKC and ERK phosphorylation significantly reduced agonist-induced hGLP-1R internalisation. These inhibitors also suppressed agonist-induced ERK1/2 phosphorylation demonstrating that the phosphorylated ERK acts downstream of the Gαq pathway in the hGLP-1R internalisation. In summary, agonist-induced hGLP-1R internalisation is mediated by the Gαq pathway. The internalised hGLP-1R stimulates insulin secretion from pancreatic β-cells, indicating the importance of GLP-1 internalisation for insulin secretion. Copyright © 2014 Elsevier Inc. All rights reserved.

Glucagon-like peptide receptor agonists and dipeptidyl peptidase-4 inhibitors in the treatment of diabetes: a review of clinical trials

DEFF Research Database (Denmark)

Madsbad, Sten; Krarup, Thure; Deacon, Carolyn F

2008-01-01

-acting glucagon-like peptide-1 receptor agonists liraglutide and exenatide long-acting release reduce haemoglobin A1c by about 1.0-2.0% and have fewer gastrointestinal side-effects. The orally available dipeptidyl peptidase-4 inhibitors, that is sitagliptin and vildagliptin reduce haemoglobin A1c by 0...

Discovery and cardioprotective effects of the first non-Peptide agonists of the G protein-coupled prokineticin receptor-1.

Directory of Open Access Journals (Sweden)

Adeline Gasser

Full Text Available Prokineticins are angiogenic hormones that activate two G protein-coupled receptors: PKR1 and PKR2. PKR1 has emerged as a critical mediator of cardiovascular homeostasis and cardioprotection. Identification of non-peptide PKR1 agonists that contribute to myocardial repair and collateral vessel growth hold promises for treatment of heart diseases. Through a combination of in silico studies, medicinal chemistry, and pharmacological profiling approaches, we designed, synthesized, and characterized the first PKR1 agonists, demonstrating their cardioprotective activity against myocardial infarction (MI in mice. Based on high throughput docking protocol, 250,000 compounds were computationally screened for putative PKR1 agonistic activity, using a homology model, and 10 virtual hits were pharmacologically evaluated. One hit internalizes PKR1, increases calcium release and activates ERK and Akt kinases. Among the 30 derivatives of the hit compound, the most potent derivative, IS20, was confirmed for its selectivity and specificity through genetic gain- and loss-of-function of PKR1. Importantly, IS20 prevented cardiac lesion formation and improved cardiac function after MI in mice, promoting proliferation of cardiac progenitor cells and neovasculogenesis. The preclinical investigation of the first PKR1 agonists provides a novel approach to promote cardiac neovasculogenesis after MI.

Design of Glucagon-Like Peptide-1 Receptor Agonist for Diabetes Mellitus from Traditional Chinese Medicine

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Hsin-Chieh Tang

2014-01-01

Full Text Available Glucagon-like peptide-1 (GLP-1 is a promising target for diabetes mellitus (DM therapy and reduces the occurrence of diabetes due to obesity. However, GLP-1 will be hydrolyzed soon by the enzyme dipeptidyl peptidase-4 (DPP-4. We tried to design small molecular drugs for GLP-1 receptor agonist from the world's largest traditional Chinese medicine (TCM Database@Taiwan. According to docking results of virtual screening, we selected 2 TCM compounds, wenyujinoside and 28-deglucosylchikusetsusaponin IV, for further molecular dynamics (MD simulation. GLP-1 was assigned as the control compound. Based on the results of root mean square deviation (RMSD, solvent accessible surface (SAS, mean square deviation (MSD, Gyrate, total energy, root mean square fluctuation (RMSF, matrices of smallest distance of residues, database of secondary structure assignment (DSSP, cluster analysis, and distance of H-bond, we concluded that all the 3 compounds could bind and activate GLP-1 receptor by computational simulation. Wenyujinoside and 28-deglucosylchikusetsusaponin IV were the TCM compounds that could be GLP-1 receptor agonists.

Mycobacteria attenuate nociceptive responses by formyl peptide receptor triggered opioid peptide release from neutrophils.

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Heike L Rittner

2009-04-01

Full Text Available In inflammation, pain is regulated by a balance of pro- and analgesic mediators. Analgesic mediators include opioid peptides which are secreted by neutrophils at the site of inflammation, leading to activation of opioid receptors on peripheral sensory neurons. In humans, local opioids and opioid peptides significantly downregulate postoperative as well as arthritic pain. In rats, inflammatory pain is induced by intraplantar injection of heat inactivated Mycobacterium butyricum, a component of complete Freund's adjuvant. We hypothesized that mycobacterially derived formyl peptide receptor (FPR and/or toll like receptor (TLR agonists could activate neutrophils, leading to opioid peptide release and inhibition of inflammatory pain. In complete Freund's adjuvant-induced inflammation, thermal and mechanical nociceptive thresholds of the paw were quantified (Hargreaves and Randall-Selitto methods, respectively. Withdrawal time to heat was decreased following systemic neutrophil depletion as well as local injection of opioid receptor antagonists or anti-opioid peptide (i.e. Met-enkephalin, beta-endorphin antibodies indicating an increase in pain. In vitro, opioid peptide release from human and rat neutrophils was measured by radioimmunoassay. Met-enkephalin release was triggered by Mycobacterium butyricum and formyl peptides but not by TLR-2 or TLR-4 agonists. Mycobacterium butyricum induced a rise in intracellular calcium as determined by FURA loading and calcium imaging. Opioid peptide release was blocked by intracellular calcium chelation as well as phosphoinositol-3-kinase inhibition. The FPR antagonists Boc-FLFLF and cyclosporine H reduced opioid peptide release in vitro and increased inflammatory pain in vivo while TLR 2/4 did not appear to be involved. In summary, mycobacteria activate FPR on neutrophils, resulting in tonic secretion of opioid peptides from neutrophils and in a decrease in inflammatory pain. Future therapeutic strategies may aim

Efficacy and Safety of GLP-1 Receptor Agonists for Type 2 Diabetes Mellitus Treatment: Systematic Review

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Ana Paula Martins

2016-04-01

Full Text Available Introduction: Glucagon-like peptide analogues are a new class of drugs used in the treatment of type 2 diabetes mellitus that mimic the endogenous hormone glucagon-like peptide 1. Glucagon-like peptide 1 regulates glucose levels by stimulating glucose-dependent insulin secretion, suppressing glucagon secretion, delayed gastric emptying and promoting satiety. The individualized treatment of type 2 diabetes mellitus, using various glucagon--like peptide receptor agonists, has recently been described and the interest related to these drugs continues to grow. Objectives: To review the efficacy and safety of glucagon-like peptide 1 agonists in patients with inadequately controlled type 2 diabetes mellitus on metformin alone, highlighting their added value in therapeutic use comparatively to second line oral therapies used in type 2 diabetes mellitus. Methods: Studies were obtained from electronic searches of The Cochrane Library and PubMed. Randomized controlled trials were selected if they were at least 8 weeks in duration; compared a glucagon-like peptide 1 analogue with an oral anti-diabetic agent in patients experiencing inadequate glycemic control with metformin monotherapy; and reported hemoglobin A1c data in non-pregnant adults with type 2 diabetes mellitus. Results: Of 72 potentially relevant articles identified, 23 were retrieved for detailed evaluation and 10 met the inclusion criteria. The majority of glucagon-like peptide 1 agonists showed equivalent or superior efficacy than most active comparators for reducing hemoglobin A1c, with a greater proportion of patients achieving hemoglobin A1c <7%. Glucagon-like peptide 1 agonists also showed extra-glycemic effects such as weight loss and the reduction of important cardiovascular parameters. Side effects included gastrointestinal complications, mainly nausea, vomiting and diarrhea. The incidence of hypoglycemia was less common for this class of agents. Conclusion: Glucagon-like peptide 1

Would glucagon-like peptide-1 receptor agonists have efficacy in binge eating disorder and bulimia nervosa? A review of the current literature.

Science.gov (United States)

McElroy, Susan L; Mori, Nicole; Guerdjikova, Anna I; Keck, Paul E

2018-02-01

Binge eating, eating an abnormally large amount of food in a discrete period of time with a sense of loss of control over eating, is a defining feature of the eating disorders binge eating disorder (BED) and bulimia nervosa (BN). Both BED and BN are important public health problems for which there are few medical treatments. However, almost all drugs with central nervous system-mediated weight loss properties studied thus far in randomized, placebo-controlled trials in persons with BED or BN have been efficacious for reducing binge eating behavior. Glucagon-like peptide-1 (GLP-1) receptor agonists, marketed for type 2 diabetes and chronic weight management, produce weight loss in a dose dependent manner and have favorable psychiatric adverse event profiles. We hypothesize that GLP-1 receptor agonists will safely reduce binge eating behavior in individuals with BED or BN, including those with co-occurring psychiatric disorders, and propose that randomized, placebo-controlled clinical trials of GLP-1 receptor agonists be conducted in persons with BED and those with BN. To support this hypothesis, we review studies of GLP-1 and GLP-1 receptor agonists in preclinical models of binge eating, studies of GLP-1 levels in individuals with BED or BN, and preliminary data of GLP-1 receptor agonists in humans with abnormal eating behavior. Copyright © 2018 Elsevier Ltd. All rights reserved.

Comparison Review of Short-Acting and Long-Acting Glucagon-like Peptide-1 Receptor Agonists.

Science.gov (United States)

Uccellatore, Annachiara; Genovese, Stefano; Dicembrini, Ilaria; Mannucci, Edoardo; Ceriello, Antonio

2015-09-01

Glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1 RAs) are useful tools for treating type 2 diabetes mellitus. In their recent position statement, the American Diabetes Association and European Association for the Study of Diabetes recommend GLP1-RAs as add-on to metformin when therapeutic goals are not achieved with monotherapy, particularly for patients who wish to avoid weight gain or hypoglycemia. GLP1-RAs differ substantially in their duration of action, frequency of administration and clinical profile. Members of this class approved for clinical use include exenatide twice-daily, exenatide once-weekly, liraglutide and lixisenatide once-daily. Recently, two new once-weekly GLP1-RAs have been approved: dulaglutide and albiglutide. This article summarizes properties of short- and long-acting GLP-1 analogs, and provides useful information to help choose the most appropriate compound for individual patients.

Small-molecule agonists for the glucagon-like peptide 1 receptor

DEFF Research Database (Denmark)

Knudsen, Lotte Bjerre; Kiel, Dan; Teng, Min

2007-01-01

and independent agonists. Potency of GLP-1 was not changed by the allosteric agonists, but affinity of GLP-1 for the receptor was increased. The most potent compound identified stimulates glucose-dependent insulin release from normal mouse islets but, importantly, not from GLP-1 receptor knockout mice. Also...

Design and development of a peptide-based adiponectin receptor agonist for cancer treatment

Directory of Open Access Journals (Sweden)

Lovas Sandor

2011-10-01

Full Text Available Abstract Background Adiponectin, a fat tissue-derived adipokine, exhibits beneficial effects against insulin resistance, cardiovascular disease, inflammatory conditions, and cancer. Circulating adiponectin levels are decreased in obese individuals, and this feature correlates with increased risk of developing several metabolic, immunological and neoplastic diseases. Thus, pharmacological replacement of adiponectin might prove clinically beneficial, especially for the obese patient population. At present, adiponectin-based therapeutics are not available, partly due to yet unclear structure/function relationships of the cytokine and difficulties in converting the full size adiponectin protein into a viable drug. Results We aimed to generate adiponectin-based short peptide that can mimic adiponectin action and be suitable for preclinical and clinical development as a cancer therapeutic. Using a panel of 66 overlapping 10 amino acid-long peptides covering the entire adiponectin globular domain (residues 105-254, we identified the 149-166 region as the adiponectin active site. Three-dimensional modeling of the active site and functional screening of additional 330 peptide analogs covering this region resulted in the development of a lead peptidomimetic, ADP 355 (H-DAsn-Ile-Pro-Nva-Leu-Tyr-DSer-Phe-Ala-DSer-NH2. In several adiponectin receptor-positive cancer cell lines, ADP 355 restricted proliferation in a dose-dependent manner at 100 nM-10 μM concentrations (exceeding the effects of 50 ng/mL globular adiponectin. Furthermore, ADP 355 modulated several key signaling pathways (AMPK, Akt, STAT3, ERK1/2 in an adiponectin-like manner. siRNA knockdown experiments suggested that ADP 355 effects can be transmitted through both adiponectin receptors, with a greater contribution of AdipoR1. In vivo, intraperitoneal administration of 1 mg/kg/day ADP 355 for 28 days suppressed the growth of orthotopic human breast cancer xenografts by ~31%. The peptide

Identification and mapping of linear antibody epitopes in human serum albumin using high-density Peptide arrays.

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Lajla Bruntse Hansen

Full Text Available We have recently developed a high-density photolithographic, peptide array technology with a theoretical upper limit of 2 million different peptides per array of 2 cm(2. Here, we have used this to perform complete and exhaustive analyses of linear B cell epitopes of a medium sized protein target using human serum albumin (HSA as an example. All possible overlapping 15-mers from HSA were synthesized and probed with a commercially available polyclonal rabbit anti-HSA antibody preparation. To allow for identification of even the weakest epitopes and at the same time perform a detailed characterization of key residues involved in antibody binding, the array also included complete single substitution scans (i.e. including each of the 20 common amino acids at each position of each 15-mer peptide. As specificity controls, all possible 15-mer peptides from bovine serum albumin (BSA and from rabbit serum albumin (RSA were included as well. The resulting layout contained more than 200.000 peptide fields and could be synthesized in a single array on a microscope slide. More than 20 linear epitope candidates were identified and characterized at high resolution i.e. identifying which amino acids in which positions were needed, or not needed, for antibody interaction. As expected, moderate cross-reaction with some peptides in BSA was identified whereas no cross-reaction was observed with peptides from RSA. We conclude that high-density peptide microarrays are a very powerful methodology to identify and characterize linear antibody epitopes, and should advance detailed description of individual specificities at the single antibody level as well as serologic analysis at the proteome-wide level.

Identification and mapping of linear antibody epitopes in human serum albumin using high-density Peptide arrays.

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Hansen, Lajla Bruntse; Buus, Soren; Schafer-Nielsen, Claus

2013-01-01

We have recently developed a high-density photolithographic, peptide array technology with a theoretical upper limit of 2 million different peptides per array of 2 cm(2). Here, we have used this to perform complete and exhaustive analyses of linear B cell epitopes of a medium sized protein target using human serum albumin (HSA) as an example. All possible overlapping 15-mers from HSA were synthesized and probed with a commercially available polyclonal rabbit anti-HSA antibody preparation. To allow for identification of even the weakest epitopes and at the same time perform a detailed characterization of key residues involved in antibody binding, the array also included complete single substitution scans (i.e. including each of the 20 common amino acids) at each position of each 15-mer peptide. As specificity controls, all possible 15-mer peptides from bovine serum albumin (BSA) and from rabbit serum albumin (RSA) were included as well. The resulting layout contained more than 200.000 peptide fields and could be synthesized in a single array on a microscope slide. More than 20 linear epitope candidates were identified and characterized at high resolution i.e. identifying which amino acids in which positions were needed, or not needed, for antibody interaction. As expected, moderate cross-reaction with some peptides in BSA was identified whereas no cross-reaction was observed with peptides from RSA. We conclude that high-density peptide microarrays are a very powerful methodology to identify and characterize linear antibody epitopes, and should advance detailed description of individual specificities at the single antibody level as well as serologic analysis at the proteome-wide level.

Update in Cardiovascular Safety of Glucagon Like Peptide-1 Receptor Agonists In Patients With Type 2 Diabetes. A Mixed Treatment Comparison Meta-Analysis of Randomised Controlled Trials.

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Al Yami, Majed S; Alfayez, Osamah M; Alsheikh, Razan

2018-03-29

The aim of this mixed treatment comparison (MTC) meta-analysis was to determine glucagon like peptide-1 (GLP-1) receptor agonists' effects on cardiovascular (CV) outcomes in patients with type 2 diabetes (T2DM). A comprehensive, systematic review was conducted using EMBASE and Medline databases. All included trials were large CV outcome trials of GLP-1 agonists versus placebo in T2DM. The primary outcomes of this MTC meta-analysis were death from CV causes, non-fatal MI, and non-fatal stroke. Hospitalisation for heart failure (HF) was evaluated as a secondary endpoint. A total of four trials, including 33,457 patients, met eligibility criteria and were retained for the meta-analysis. Our pairwise meta-analysis results showed a 13% reduction in death from cardiovascular causes in patients who received GLP-1 agonists versus placebo (RR 0.87, 95% CI: 0.78-0.96). However, no statistically significant reduction was observed with GLP-1 agonists in terms of reducing non-fatal MI (RR 0.95, 95% CI: 0.86-1.04), non-fatal stroke events (RR 0.89, 95% CI: 0.76-1.03), and rates of HF hospitalisation (RR 0.94, 95% CI: 0.84-1.04). The network meta-analysis (NMA) showed no significant differences among all the interventions. Glucagon like peptide-1 therapy was associated with a significant reduction in cardiovascular (CV) death. However, GLP-1 agonists seem to have a safety profile comparable to placebo in terms of reducing non-fatal myocardial infarction (MI), non-fatal stroke events, and rates of HF hospitalisation. Copyright © 2018 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

Potent μ-Opioid Receptor Agonists from Cyclic Peptides Tyr-c[D-Lys-Xxx-Tyr-Gly]: Synthesis, Biological, and Structural Evaluation.

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Li, Yangmei; Cazares, Margret; Wu, Jinhua; Houghten, Richard A; Toll, Laurence; Dooley, Colette

2016-02-11

To optimize the structure of a μ-opioid receptor ligand, analogs H-Tyr-c[D-Lys-Xxx-Tyr-Gly] were synthesized and their biological activity was tested. The analog containing a Phe(3) was identified as not only exhibiting binding affinity 14-fold higher than the original hit but also producing agonist activity 3-fold more potent than morphine. NMR study suggested that a trans conformation at D-Lys(2)-Xxx(3) is crucial for these cyclic peptides to maintain high affinity, selectivity, and functional activity toward the μ-opioid receptor.

Synthesis and Pharmacology of Halogenated δ-Opioid-Selective [D-Ala2]Deltorphin II Peptide Analogues

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Pescatore, Robyn; Marrone, Gina F.; Sedberry, Seth; Vinton, Daniel; Finkelstein, Netanel; Katlowitz, Yitzchak E.; Pasternak, Gavril W.; Wilson, Krista R.; Majumdar, Susruta

2015-01-01

Deltorphins are naturally occurring peptides produced by the skin of the giant monkey frog (Phyllomedusa bicolor). They are δ-opioid receptor-selective agonists. Herein, we report the design and synthesis of a peptide, Tyr-D-Ala-(pI)Phe-Glu-Ile-Ile-Gly-NH2 3 (GATE3-8), based on the [D-Ala2]deltorphin II template, which is δ-selective in in vitro radioligand binding assays over the μ- and κ-opioid receptors. It is a full agonist in [35S]GTPγS functional assays and analgesic when administered supraspinally to mice. Analgesia of 3 (GATE3-8) is blocked by the selective δ receptor antagonist naltrindole, indicating that the analgesic action of 3 is mediated by the δ-opioid receptor. We have established a radioligand in which 125I isincorporated into 3 (GATE3-8). The radioligand has a KD of 0.1 nM in Chinese hamster ovary (CHO) cells expressing the δ receptor. Additionally, a series of peptides based on 3 (GATE3-8) was synthesized by incorporating various halogens in the para position on the aromatic ring of Phe3. The peptides were characterized for binding affinity at the μ-, δ-, and κ-opioid receptors, which showed a linear correlation between binding affinity and the size of the halogen substituent. These peptides may be interesting tools for probing δ-opioid receptor pharmacology. PMID:25844930

Synthesis and pharmacology of halogenated δ-opioid-selective [d-Ala(2)]deltorphin II peptide analogues.

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Pescatore, Robyn; Marrone, Gina F; Sedberry, Seth; Vinton, Daniel; Finkelstein, Netanel; Katlowitz, Yitzchak E; Pasternak, Gavril W; Wilson, Krista R; Majumdar, Susruta

2015-06-17

Deltorphins are naturally occurring peptides produced by the skin of the giant monkey frog (Phyllomedusa bicolor). They are δ-opioid receptor-selective agonists. Herein, we report the design and synthesis of a peptide, Tyr-d-Ala-(pI)Phe-Glu-Ile-Ile-Gly-NH2 3 (GATE3-8), based on the [d-Ala(2)]deltorphin II template, which is δ-selective in in vitro radioligand binding assays over the μ- and κ-opioid receptors. It is a full agonist in [(35)S]GTPγS functional assays and analgesic when administered supraspinally to mice. Analgesia of 3 (GATE3-8) is blocked by the selective δ receptor antagonist naltrindole, indicating that the analgesic action of 3 is mediated by the δ-opioid receptor. We have established a radioligand in which (125)I is incorporated into 3 (GATE3-8). The radioligand has a KD of 0.1 nM in Chinese hamster ovary (CHO) cells expressing the δ receptor. Additionally, a series of peptides based on 3 (GATE3-8) was synthesized by incorporating various halogens in the para position on the aromatic ring of Phe(3). The peptides were characterized for binding affinity at the μ-, δ-, and κ-opioid receptors, which showed a linear correlation between binding affinity and the size of the halogen substituent. These peptides may be interesting tools for probing δ-opioid receptor pharmacology.

Development of novel ligands for peptide GPCRs.

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Moran, Brian M; McKillop, Aine M; O'Harte, Finbarr Pm

2016-12-01

Incretin based glucagon-like peptide-1 receptor (GLP-1R) agonists which target a G-protein coupled receptor (GPCR) are currently used in the treatment of type 2 diabetes. This review focuses on GPCRs from pancreatic β-cells, including GLP-1, glucose-dependent insulinotropic polypeptide (GIP), glucagon, somatostatin, pancreatic polypeptide (PP), cholecystokinin (CCK), peptide YY (PYY), oxyntomodulin (OXM) and ghrelin receptors. In addition, fatty acids GPCRs are thought to have an increasing role in regulating peptide secretions namely short fatty acids GPCR (GPR41, GPR43), medium chain fatty acid GPCR (GPR84), long chain fatty acid GPCR (GPR40, GPR120) and cannabinoid-like GPCR (GPR55, GPR119). Several pre-clinical and clinical trials are currently ongoing in peptide GPCR based therapies, including dual and triple agonist peptides which activate two or more GPCRs simultaneously. Copyright © 2016 Elsevier Ltd. All rights reserved.

Overlapping binding site for the endogenous agonist, small-molecule agonists, and ago-allosteric modulators on the ghrelin receptor

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Holst, Birgitte; Frimurer, Thomas M; Mokrosinski, Jacek

2008-01-01

A library of robust ghrelin receptor mutants with single substitutions at 22 positions in the main ligand-binding pocket was employed to map binding sites for six different agonists: two peptides (the 28-amino-acid octanoylated endogenous ligand ghrelin and the hexapeptide growth hormone......, and PheVI:23 on the opposing face of transmembrane domain (TM) VI. Each of the agonists was also affected selectively by specific mutations. The mutational map of the ability of L-692,429 and GHRP-6 to act as allosteric modulators by increasing ghrelin's maximal efficacy overlapped with the common....... It is concluded that although each of the ligands in addition exploits other parts of the receptor, a large, common binding site for both small-molecule agonists--including ago-allosteric modulators--and the endogenous agonist is found on the opposing faces of TM-III and -VI of the ghrelin receptor....

Novel kinin B1 receptor agonists with improved pharmacological profiles.

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Côté, Jérôme; Savard, Martin; Bovenzi, Veronica; Bélanger, Simon; Morin, Josée; Neugebauer, Witold; Larouche, Annie; Dubuc, Céléna; Gobeil, Fernand

2009-04-01

There is some evidence to suggest that inducible kinin B1 receptors (B1R) may play beneficial and protecting roles in cardiovascular-related pathologies such as hypertension, diabetes, and ischemic organ diseases. Peptide B1R agonists bearing optimized pharmacological features (high potency, selectivity and stability toward proteolysis) hold promise as valuable therapeutic agents in the treatment of these diseases. In the present study, we used solid-phase methodology to synthesize a series of novel peptide analogues based on the sequence of Sar[dPhe(8)]desArg(9)-bradykinin, a relatively stable peptide agonist with moderate affinity for the human B1R. We evaluated the pharmacological properties of these peptides using (1) in vitro competitive binding experiments on recombinant human B1R and B2R (for index of selectivity determination) in transiently transfected human embryonic kidney 293 cells (HEK-293T cells), (2) ex vivo vasomotor assays on isolated human umbilical veins expressing endogenous human B1R, and (3) in vivo blood pressure tests using anesthetized lipopolysaccharide-immunostimulated rabbits. Key chemical modifications at the N-terminus, the positions 3 and 5 on Sar[dPhe(8)]desArg(9)-bradykinin led to potent analogues. For example, peptides 18 (SarLys[Hyp(3),Cha(5), dPhe(8)]desArg(9)-bradykinin) and 20 (SarLys[Hyp(3),Igl(5), dPhe(8)]desArg(9)-bradykinin) outperformed the parental molecule in terms of affinity, functional potency and duration of action in vitro and in vivo. These selective agonists should be valuable in future animal and human studies to investigate the potential benefits of B1R activation.

The lipidated peptidomimetic Lau-[(S)-Aoc]-(Lys-βNphe)6-NH2 is a novel formyl peptide receptor 2 agonist that activates both human and mouse neutrophil NADPH-oxidase

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Holdfeldt, Andre; Skovbakke, Sarah Line; Winther, Malene

2016-01-01

Neutrophils expressing formyl peptide receptor 2 (FPR2) play key roles in host defense, immune regulation, and resolution of inflammation. Consequently, the search for FPR2-specific modulators has attracted much attention due to its therapeutic potential. Earlier described agonists......2 (F2M2), showing comparable potency in activating human and mouse neutrophils by inducing a rise in intracellular Ca2+ concentration and assembly of the superoxide-generating NADPH oxidase. This FPR2/Fpr2 agonist contains a headgroup consisting of a 2-aminooctanoic acid (Aoc) residue acylated......2 signaling as well as for development of prophylactic immunomodulatory therapy. This novel class of cross-species FPR2/Fpr2 agonists should enable translation of results obtained with mouse neutrophils (and disease models) into enhanced understanding of human inflammatory and immune diseases....

Reversal of obesity and insulin resistance by a non-peptidic glucagon-like peptide-1 receptor agonist in diet-induced obese mice.

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Min He

Full Text Available BACKGROUND: Glucagon-like peptide-1 (GLP-1 is recognized as an important regulator of glucose homeostasis. Efforts to utilize GLP-1 mimetics in the treatment of diabetes have yielded clinical benefits. A major hurdle for an effective oral therapy has been the difficulty of finding a non-peptidic GLP-1 receptor (GLP-1R agonist. While its oral bioavailability still poses significant challenges, Boc5, one of the first such compounds, has demonstrated the attainment of GLP-1R agonism in diabetic mice. The present work was to investigate whether subchronic Boc5 treatment can restore glycemic control and induce sustainable weight loss in diet-induced obese (DIO mice, an animal model of human obesity and insulin resistance. METHODOLOGY/PRINCIPAL FINDINGS: DIO mice were treated three times a week with Boc5 (0.3, 1 and 3 mg for 12 weeks. Body weight, body mass index (BMI, food intake, fasting glucose, intraperitoneal glucose tolerance and insulin induced glucose clearance were monitored regularly throughout the treatment. Glucose-stimulated insulin secretion, β-cell mass, islet size, body composition, serum metabolic profiles, lipogenesis, lipolysis, adipose hypertrophy and lipid deposition in the liver and muscle were also measured after 12 weeks of dosing. Boc5 dose-dependently reduced body weight, BMI and food intake in DIO mice. These changes were associated with significant decreases in fat mass, adipocyte hypertrophy and peripheral tissue lipid accumulation. Boc5 treatment also restored glycemic control through marked improvement of insulin sensitivity and normalization of β-cell mass. Administration of Boc5 (3 mg reduced basal but enhanced insulin-mediated glucose incorporation and noradrenaline-stimulated lipolysis in isolated adipocytes from obese mice. Furthermore, circulating leptin, adiponectin, triglyceride, total cholesterol, nonesterified fatty acid and high-density lipoprotein/low-density lipoprotein ratio were normalized to various

Short-acting glucagon-like peptide-1 receptor agonists as add-on to insulin therapy in type 1 diabetes

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Albèr, Anders; Brønden, Andreas; Knop, Filip K

2017-01-01

emptying in patients with type 1 diabetes, which could translate into effective lowering of postprandial glucose excursions; however, these observations regarding short-acting GLP-1RAs are all derived from small open-label trials and should thus be interpreted with caution. In the present paper we review......A large proportion of patients with type 1 diabetes do not reach their glycaemic target of glycated hemoglobin (HbA1c) type 1 diabetes are overweight and obese. Treatment of type 1 diabetes is based on insulin therapy......, which is associated with well-described and unfortunate adverse effects such as hypoglycaemia and increased body weight. Glucagon-like peptide-1 (GLP-1) receptor agonists (RAs) are the focus of increasing interest as a possible adjunctive treatment to insulin in type 1 diabetes because...

Structure-activity relationship of linear peptide Bu-His-DPhe-Arg-Trp-Gly-NH(2) at the human melanocortin-1 and -4 receptors: arginine substitution.

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Cheung, Adrian Wai-Hing; Danho, Waleed; Swistok, Joseph; Qi, Lida; Kurylko, Grazyna; Franco, Lucia; Yagaloff, Keith; Chen, Li

2002-09-02

A series of pentapeptides, based on Bu-His(6)-DPhe(7)-Arg(8)-Trp(9)-Gly(10)-NH(2) and modified at the Arg(8) position, was prepared and pharmacologically characterized. Peptides containing either cyanoguanidine or acylguanidine, two substantially less basic arginine surrogates, were found to retain the agonist activity of the parent peptide at both hMC1R and hMC4R. This study unequivocally shows that the positive charge of Arg(8) is not essential for efficient interactions of our pentapeptide with both hMC1R and hMC4R.

Peptide and small molecules rescue the functional activity and agonist potency of dysfunctional human melanocortin-4 receptor polymorphisms.

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Xiang, Zhimin; Pogozheva, Irina D; Sorenson, Nicholas B; Wilczynski, Andrzej M; Holder, Jerry Ryan; Litherland, Sally A; Millard, William J; Mosberg, Henry I; Haskell-Luevano, Carrie

2007-07-17

The melanocortin pathway, specifically the melanocortin-4 receptor and the cognate endogenous agonist and antagonist ligands, have been strongly implicated in the regulation of energy homeostasis and satiety. Genetic studies of morbidly obese human patients and normal weight control patients have resulted in the discovery of over 70 human melanocortin-4 receptor (MC4R) polymorphisms observed as both heterozygous and homozygous forms. A number of laboratories have been studying these hMC4R polymorphisms attempting to understand the molecular mechanism(s) that might explain the obese human phenotype. Herein, we have studied 13 polymorphic hMC4Rs that have been identified to possess statistically significant decreased endogenous agonist potency with synthetic peptides and small molecules attempting to identify ligands that can pharmacologically rescue the hMC4R polymorphic agonist response. The ligands examined in this study include NDP-MSH, MTII, Ac-His-DPhe-Arg-Trp-NH2 (JRH887-9), Ac-Anc-DPhe-Arg-Trp-NH2 (amino-2-naphtylcarboxylic acid, Anc, JRH420-12), Ac-His-(pI)DPhe-Arg-Trp-NH2 (JRH322-18), chimeric AGRP-melanocortin based ligands (Tyr-c[Cys-His-DPhe-Arg-Trp-Asn-Ala-Phe-Cys]-Tyr-NH2, AMW3-130 and Ac-mini-(His-DPhe-Arg-Trp)-hAGRP-NH2, AMW3-106), and the small molecules JB25 and THIQ. The hMC4R polymorphisms included in this study are S58C, N97D, I102S, L106P, S127L, T150I, R165Q, R165W, L250Q, G252S, C271Y, Y287Stop, and I301T. These studies resulted in the NDP-MSH, MTII, AMW3-130, THIQ, and AMW3-106 ligands possessing nanomolar to subnanomolar agonist potency at the hMC4R polymorphisms examined in this study. Thus, these ligands could generically rescue the potency and stimulatory response of the abnormally functioning hMC4Rs studied and may provide tools to further clarify the molecular mechanism(s) involving these receptor modifications.

Unique interaction pattern for a functionally biased ghrelin receptor agonist

DEFF Research Database (Denmark)

Sivertsen, Bjørn Behrens; Lang, Manja; Frimurer, Thomas M.

2011-01-01

Based on the conformationally constrained D-Trp-Phe-D-Trp (wFw) core of the prototype inverse agonist [D-Arg(1),D-Phe(5),D-Trp(7,9),Leu(11)]substance P, a series of novel, small, peptide-mimetic agonists for the ghrelin receptor were generated. By using various simple, ring-constrained spacers...... connecting the D-Trp-Phe-D-Trp motif with the important C-terminal carboxyamide group, 40 nm agonism potency was obtained and also in one case (wFw-Isn-NH(2), where Isn is isonipecotic acid) ~80% efficacy. However, in contrast to all previously reported ghrelin receptor agonists, the piperidine-constrained w......Fw-Isn-NH(2) was found to be a functionally biased agonist. Thus, wFw-Isn-NH(2) mediated potent and efficacious signaling through the Ga(q) and ERK1/2 signaling pathways, but in contrast to all previous ghrelin receptor agonists it did not signal through the serum response element, conceivably the Ga(12...

Direct peptide bioconjugation/PEGylation at tyrosine with linear and branched polymeric diazonium salts.

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Jones, Mathew W; Mantovani, Giuseppe; Blindauer, Claudia A; Ryan, Sinead M; Wang, Xuexuan; Brayden, David J; Haddleton, David M

2012-05-02

Direct polymer conjugation at peptide tyrosine residues is described. In this study Tyr residues of both leucine enkephalin and salmon calcitonin (sCT) were targeted using appropriate diazonium salt-terminated linear monomethoxy poly(ethylene glycol)s (mPEGs) and poly(mPEG) methacrylate prepared by atom transfer radical polymerization. Judicious choice of the reaction conditions-pH, stoichiometry, and chemical structure of diazonium salt-led to a high degree of site-specificity in the conjugation reaction, even in the presence of competitive peptide amino acid targets such as histidine, lysines, and N-terminal amine. In vitro studies showed that conjugation of mPEG(2000) to sCT did not affect the peptide's ability to increase intracellular cAMP induced in T47D human breast cancer cells bearing sCT receptors. Preliminary in vivo investigation showed preserved ability to reduce [Ca(2+)] plasma levels by mPEG(2000)-sCT conjugate in rat animal models. © 2012 American Chemical Society

Neuromedin and FN-38 Peptides for Treating Psychiatric Diseases

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Methods and compositions for treating psychiatric diseases and disorders are disclosed. The methods provided generally involve the administration of an NMX peptide, an FNX peptide, or an NMX receptor agonist, or analogs or derivatives thereof, to a subject in order to treat psychiatric diseases and ...

[Effects of GLP-1 receptor agonists on carbohydrate metabolism control].

Science.gov (United States)

Fernández-García, José Carlos; Colomo, Natalia; Tinahones, Francisco José

2014-09-01

Glucagon-like peptide-1 (GLP-1) receptor agonists are a new group of drugs for the treatment of type 2 diabetes mellitus (DM2). In the present article, we review the available evidence on the efficacy of GLP-1 receptor agonists as glucose-lowering agents, their place in therapeutic algorithms, and the clinical factors associated with a favorable treatment response. Finally, we describe the clinical characteristics of patients who may benefit from these drugs. Copyright © 2014 Elsevier España, S.L.U. All rights reserved.

The amphiphilic peptide adenoregulin enhances agonist binding to A1-adenosine receptors and [35S]GTP gamma S to brain membranes.

Science.gov (United States)

Moni, R W; Romero, F S; Daly, J W

1995-08-01

1. Adenoregulin is an amphilic peptide isolated from skin mucus of the tree frog, Phyllomedusa bicolor. Synthetic adenoregulin enhanced the binding of agonists to several G-protein-coupled receptors in rat brain membranes. 2. The maximal enhancement of agonist binding, and in parentheses, the concentration of adenoregulin affording maximal enhancement were as follows: 60% (20 microM) for A1-adenosine receptors, 30% (100 microM) for A2a-adenosine receptors, 20% (2 microM) for alpha 2-adrenergic receptors, and 30% (10 microM) for 5HT1A receptors. High affinity agonist binding for A1-, alpha 2-, and 5HT1A-receptors was virtually abolished by GTP gamma S in the presence of adenoregulin, but was only partially abolished in its absence. Magnesium ions increased the binding of agonists to receptors and reduced the enhancement elicited by adenoregulin. 3. The effect of adenoregulin on binding of N6-cyclohexyladenosine ([3H]CHA) to A1-receptors was relatively slow and was irreversible. Adenoregulin increased the Bmax value for [3H]CHA binding sites, and the proportion of high affinity states, and slowed the rate of [3H]CHA dissociation. Binding of the A1-selective antagonist, [3H]DPCPX, was maximally enhanced by only 13% at 2 microM adenoregulin. Basal and A1-adenosine receptor-stimulated binding of [35S]GTP gamma S were maximally enhanced 45% and 23%, respectively, by 50 microM adenoregulin. In CHAPS-solubilized membranes from rat cortex, the binding of both [3H]CHA and [3H]DPCPX were enhanced by adenoregulin. Binding of [3H]CHA to membranes from DDT1 MF-2 cells was maximally enhanced 17% at 20 microM adenoregulin. In intact DDT1 MF-2 cells, 20 microM adenoregulin did not potentiate the inhibition of cyclic AMP accumulation mediated via the adenosine A1 receptor. 4. It is proposed that adenoregulin enhances agonist binding through a mechanism involving enhancement of guanyl nucleotide exchange at G-proteins, resulting in a conversion of receptors into a high affinity state

Synthesis and Pharmacology of α/β(3)-Peptides Based on the Melanocortin Agonist Ac-His-dPhe-Arg-Trp-NH2 Sequence.

Science.gov (United States)

Singh, Anamika; Tala, Srinivasa R; Flores, Viktor; Freeman, Katie; Haskell-Luevano, Carrie

2015-05-14

The melanocortin-3 and -4 receptors are expressed in the brain and play key roles in regulating feeding behavior, metabolism, and energy homeostasis. In the present study, incorporation of β(3)-amino acids into a melanocortin tetrapeptide template was investigated. Four linear α/β(3)-hybrid tetrapeptides were designed with the modifications at the Phe, Arg, and Trp residues in the agonist sequence Ac-His-dPhe-Arg-Trp-NH2. The most potent mouse melanocortin-4 receptor (mMC4R) agonist, Ac-His-dPhe-Arg-β(3)hTrp-NH2 (8) showed 35-fold selectivity versus the mMC3R. The study presented here has identified a new template with heterogeneous backbone for designing potent and selective melanocortin receptor ligands.

Synthesis and Pharmacology of α/β3-Peptides Based on the Melanocortin Agonist Ac-His-dPhe-Arg-Trp-NH2 Sequence

Science.gov (United States)

2015-01-01

The melanocortin-3 and -4 receptors are expressed in the brain and play key roles in regulating feeding behavior, metabolism, and energy homeostasis. In the present study, incorporation of β3-amino acids into a melanocortin tetrapeptide template was investigated. Four linear α/β3-hybrid tetrapeptides were designed with the modifications at the Phe, Arg, and Trp residues in the agonist sequence Ac-His-dPhe-Arg-Trp-NH2. The most potent mouse melanocortin-4 receptor (mMC4R) agonist, Ac-His-dPhe-Arg-β3hTrp-NH2 (8) showed 35-fold selectivity versus the mMC3R. The study presented here has identified a new template with heterogeneous backbone for designing potent and selective melanocortin receptor ligands. PMID:26005535

A Glucagon-Like Peptide-1 Receptor Agonist Lowers Weight by Modulating the Structure of Gut Microbiota

Directory of Open Access Journals (Sweden)

Li Zhao

2018-05-01

Full Text Available In addition to improving glucose metabolism, liraglutide, a glucagon-like peptide-1 receptor agonist, has weight-loss effects. The underlying mechanisms are not completely understood. This study was performed to explore whether liraglutide could lower weight by modulating the composition of the gut microbiota in simple obese and diabetic obese rats. In our study, Wistar and Goto-Kakizaki (GK rats were randomly treated with liraglutide or normal saline for 12 weeks. The biochemical parameters and metabolic hormones were measured. Hepatic glucose production and lipid metabolism were also assessed with isotope tracers. Changes in gut microbiota were analyzed by 16S rRNA gene sequencing. Both glucose and lipid metabolism were significantly improved by liraglutide. Liraglutide lowered body weight independent of glycemia status. The abundance and diversity of gut microbiota were considerably decreased by liraglutide. Liraglutide also decreased obesity-related microbial phenotypes and increased lean-related phenotypes. In conclusion, liraglutide can prevent weight gain by modulating the gut microbiota composition in both simple obese and diabetic obese subjects.

Chimeric peptide constructs comprising linear B-cell epitopes: application to the serodiagnosis of infectious diseases.

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Lu, Yudong; Li, Zhong; Teng, Huan; Xu, Hongke; Qi, Songnan; He, Jian'an; Gu, Dayong; Chen, Qijun; Ma, Hongwei

2015-08-21

Linear B-cell epitopes are ideal biomarkers for the serodiagnosis of infectious diseases. However, the long-predicted diagnostic value of epitopes has not been realized. Here, we demonstrated a method, diagnostic epitopes in four steps (DEIFS), that delivers a combination of epitopes for the serodiagnosis of infectious diseases with a high success rate. Using DEIFS for malaria, we identified 6 epitopes from 8 peptides and combined them into 3 chimeric peptide constructs. Along with 4 other peptides, we developed a rapid diagnostic test (RDT), which is able to differentiate Plasmodium falciparum (P. falciparum) from Plasmodium vivax (P. vivax) infections with 95.6% overall sensitivity and 99.1% overall specificity. In addition to applications in diagnosis, DEIFS could also be used in the diagnosis of virus and bacterium infections, discovery of vaccine candidates, evaluation of vaccine potency, and study of disease progression.

Evaluating preferences for profiles of glucagon-like peptide-1 receptor agonists among injection-naive type 2 diabetes patients in Japan

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Gelhorn HL

2016-07-01

Full Text Available Heather L Gelhorn,1 Elizabeth D Bacci,2 Jiat Ling Poon,1 Kristina S Boye,3 Shuichi Suzuki,4 Steven M Babineaux3 1Outcomes Research, Evidera, Bethesda, MD, 2Evidera, Seattle, WA, 3Global Patient Outcomes and Real World Evidence, Eli Lilly and Company, Indianapolis, IN, USA; 4Medicines Development Unit Japan, Eli Lilly Japan, Kobe, Japan Objective: The objective of this study was to use a discrete choice experiment (DCE to estimate patients’ preferences for the treatment features, safety, and efficacy of two specific glucagon-like peptide-1 receptor agonists, dulaglutide and liraglutide, among patients with type 2 diabetes mellitus (T2DM in Japan.Methods: In Japan, patients with self-reported T2DM and naive to treatment with self-injectable medications were administered a DCE through an in-person interview. The DCE examined the following six attributes of T2DM treatment, each described by two levels: “dosing frequency”, “hemoglobin A1c change”, “weight change”, “type of delivery system”, “frequency of nausea”, and “frequency of hypoglycemia”. Part-worth utilities were estimated using logit models and were used to calculate the relative importance (RI of each attribute. A chi-square test was used to determine the differences in preferences for the dulaglutide versus liraglutide profiles.Results: The final evaluable sample consisted of 182 participants (mean age: 58.9 [standard deviation =10.0] years; 64.3% male; mean body mass index: 26.1 [standard deviation =5.0] kg/m2. The RI values for the attributes in rank order were dosing frequency (44.1%, type of delivery system (26.3%, frequency of nausea (15.1%, frequency of hypoglycemia (7.4%, weight change (6.2%, and hemoglobin A1c change (1.0%. Significantly more participants preferred the dulaglutide profile (94.5% compared to the liraglutide profile (5.5%; P<0.0001.Conclusion: This study elicited the preferences of Japanese T2DM patients for attributes and levels

Biophysical and biological properties of small linear peptides derived from crotamine, a cationic antimicrobial/antitumoral toxin with cell penetrating and cargo delivery abilities.

Science.gov (United States)

Dal Mas, C; Pinheiro, D A; Campeiro, J D; Mattei, B; Oliveira, V; Oliveira, E B; Miranda, A; Perez, K R; Hayashi, M A F

2017-12-01

Crotamine is a natural polypeptide from snake venom which delivers nucleic acid molecules into cells, besides having pronounced affinity for negatively charged membranes and antifungal activity. We previously demonstrated that crotamine derived short linear peptides were not very effective as antifungal, although the non-structured recombinant crotamine was overridingly more potent compared to the native structured crotamine. Aiming to identify the features necessary for the antifungal activity of crotamine, two linear short peptides, each comprising half of the total positively charged amino acid residues of the full-length crotamine were evaluated here to show that these linear peptides keep the ability to interact with lipid membrane model systems with different phospholipid compositions, even after forming complexes with DNA. Interestingly, the presence of cysteine residues in the structure of these linear peptides highly influenced the antifungal activity, which was not associated to the lipid membrane lytic activity. In addition to the importance of the positive charges, the crucial role of cysteine residues was noticed for these linear analogs of crotamine, although the tridimensional structure and lipid membrane lytic activity observed only for native crotamine was not essential for the antifungal activity. As these peptides still keep the ability to form complexes with DNA molecules with no prejudice to their ability to bind to lipid membranes, they may be potentially advantageous as membrane translocation vector, as they do not show lipid membrane lytic activity and may harbor or not antifungal activity, by keeping or not the semi-essential amino acid cysteine in their sequence. Copyright © 2017 Elsevier B.V. All rights reserved.

Hyperthermic responses to central injections of some peptide and non-peptide opioids in the guinea-pig

Science.gov (United States)

Kandasamy, S. B.; Williams, B. A.

1983-01-01

The intracerebroventricular administration of prototype nonpeptide opioid receptor (mu, kappa, and sigma) agonists, morphine, ketocyclazocine, and N-allyl normetazocine and an agonist at both kappa and sigma receptors, pentazocine, was found to induce hyperthermia in guinea pigs. The similar administration of peptide opioids like beta endorphin, methionine endkephalin, leucine endkephaline, and several of their synthetic analogues was also found to cause hyperthermia. Only the liver-like transport system of the three anion transport systems (iodide, hippurate, and liver-like) present in the choroid plexus was determined to be important to the central inactivation of beta-endorphin and two synthetic analogues. Prostaglandins and norepinephrine (NE) as well as cAMP were not involved in peptide and nonpeptide opioid-induced hyperthermia. Naloxone-sensitive receptors were found to be involved in the induction of hyperthermia by morphine and beta-endorphin, while hyperthermic responses to ketocyclazocine, N-allyl normetazocine, pentazocine, Met-enkephalin, Leu-enkephalin, and two of the synthetic analogues were not antagonized by nalozone. The lack of antagonism of naloxone on pyrogen, arachidonic acid, PGE2, dibutyryl cAMP, and NE-induced hyperthermia shows that endogenous opioid peptides are not likely to be central mediators of the hyperthermia induced by these agents.

The peptidomimetic Lau-(Lys-βNSpe)6-NH2 antagonizes formyl peptide receptor 2 expressed in mouse neutrophils

DEFF Research Database (Denmark)

Skovbakke, Sarah Line; Winther, Malene; Gabl, Michael

2016-01-01

/differences between the human and murine FPR family members is required. Compared to FPR1 and FPR2 expressed by human neutrophils, very little is known about agonist/antagonist recognition patterns for their murine orthologues, but now we have identified two potent and selective formylated peptide agonists (f...... to be devoid of effect on their murine orthologues as determined by their inability to inhibit superoxide release from murine neutrophils upon stimulation with receptor-specific agonists. The Boc-FLFLF peptide was found to be a selective antagonist for Fpr1, whereas the lipidated peptidomimetic Lau...

Truncated Glucagon-like Peptide-1 and Exendin-4 α-Conotoxin pl14a Peptide Chimeras Maintain Potency and α-Helicity and Reveal Interactions Vital for cAMP Signaling in Vitro*

Science.gov (United States)

Swedberg, Joakim E.; Schroeder, Christina I.; Mitchell, Justin M.; Fairlie, David P.; Edmonds, David J.; Griffith, David A.; Ruggeri, Roger B.; Derksen, David R.; Loria, Paula M.; Price, David A.; Liras, Spiros; Craik, David J.

2016-01-01

Glucagon-like peptide-1 (GLP-1) signaling through the glucagon-like peptide 1 receptor (GLP-1R) is a key regulator of normal glucose metabolism, and exogenous GLP-1R agonist therapy is a promising avenue for the treatment of type 2 diabetes mellitus. To date, the development of therapeutic GLP-1R agonists has focused on producing drugs with an extended serum half-life. This has been achieved by engineering synthetic analogs of GLP-1 or the more stable exogenous GLP-1R agonist exendin-4 (Ex-4). These synthetic peptide hormones share the overall structure of GLP-1 and Ex-4, with a C-terminal helical segment and a flexible N-terminal tail. Although numerous studies have investigated the molecular determinants underpinning GLP-1 and Ex-4 binding and signaling through the GLP-1R, these have primarily focused on the length and composition of the N-terminal tail or on how to modulate the helicity of the full-length peptides. Here, we investigate the effect of C-terminal truncation in GLP-1 and Ex-4 on the cAMP pathway. To ensure helical C-terminal regions in the truncated peptides, we produced a series of chimeric peptides combining the N-terminal portion of GLP-1 or Ex-4 and the C-terminal segment of the helix-promoting peptide α-conotoxin pl14a. The helicity and structures of the chimeric peptides were confirmed using circular dichroism and NMR, respectively. We found no direct correlation between the fractional helicity and potency in signaling via the cAMP pathway. Rather, the most important feature for efficient receptor binding and signaling was the C-terminal helical segment (residues 22–27) directing the binding of Phe22 into a hydrophobic pocket on the GLP-1R. PMID:27226591

Small Molecule Drug Discovery at the Glucagon-Like Peptide-1 Receptor

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Francis S. Willard

2012-01-01

Full Text Available The therapeutic success of peptide glucagon-like peptide-1 (GLP-1 receptor agonists for the treatment of type 2 diabetes mellitus has inspired discovery efforts aimed at developing orally available small molecule GLP-1 receptor agonists. Although the GLP-1 receptor is a member of the structurally complex class B1 family of GPCRs, in recent years, a diverse array of orthosteric and allosteric nonpeptide ligands has been reported. These compounds include antagonists, agonists, and positive allosteric modulators with intrinsic efficacy. In this paper, a comprehensive review of currently disclosed small molecule GLP-1 receptor ligands is presented. In addition, examples of “ligand bias” and “probe dependency” for the GLP-1 receptor are discussed; these emerging concepts may influence further optimization of known molecules or persuade designs of expanded screening strategies to identify novel chemical starting points for GLP-1 receptor drug discovery.

Lack of effect of the glucagon-like peptide-1 receptor agonist liraglutide on psoriasis in glucose-tolerant patients – a randomized placebo-controlled trial

DEFF Research Database (Denmark)

Faurschou, A; Gyldenløve, M; Rohde, U

2015-01-01

BACKGROUND: It has been proposed that glucagon-like peptide-1 receptor (GLP-1R) agonists used for the treatment of patients with type 2 diabetes might also improve their psoriasis. OBJECTIVE: To assess the efficacy and safety of the GLP-1R agonist liraglutide in glucose-tolerant patients with pla...... end points were improvement in PASI and dermatology life quality index (DLQI). Secondary end points included changes in weight and high sensitive C-reactive protein (hsCRP) levels, as well as adverse events. RESULTS: After 8 weeks of treatment, no significant change in PASI was found.......2 (liraglutide); P = 0.992). Liraglutide treatment resulted in a bodyweight loss of 4.7 ± 2.5 kg compared with 1.6 ± 2.7 kg in the placebo group (P = 0.014) accompanied by decreased cholesterol levels. No serious adverse events occurred during the 8-week observation period. The most common complaint...... was transient nausea, which occurred in 45% of the liraglutide-treated patients but in none from the placebo group. CONCLUSION: Liraglutide treatment for 8 weeks did not significantly change PASI, DLQI, or hsCRP in a small group of glucose-tolerant obese patients with plaque psoriasis compared with placebo...

Cell wall trapping of autocrine peptides for human G-protein-coupled receptors on the yeast cell surface.

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Jun Ishii

Full Text Available G-protein-coupled receptors (GPCRs regulate a wide variety of physiological processes and are important pharmaceutical targets for drug discovery. Here, we describe a unique concept based on yeast cell-surface display technology to selectively track eligible peptides with agonistic activity for human GPCRs (Cell Wall Trapping of Autocrine Peptides (CWTrAP strategy. In our strategy, individual recombinant yeast cells are able to report autocrine-positive activity for human GPCRs by expressing a candidate peptide fused to an anchoring motif. Following expression and activation, yeast cells trap autocrine peptides onto their cell walls. Because captured peptides are incapable of diffusion, they have no impact on surrounding yeast cells that express the target human GPCR and non-signaling peptides. Therefore, individual yeast cells can assemble the autonomous signaling complex and allow single-cell screening of a yeast population. Our strategy may be applied to identify eligible peptides with agonistic activity for target human GPCRs.

Design of a new peptidomimetic agonist for the melanocortin receptors based on the solution structure of the peptide ligand, Ac-Nle-cyclo[Asp-Pro-DPhe-Arg-Trp-Lys]-NH(2).

Science.gov (United States)

Fotsch, Christopher; Smith, Duncan M; Adams, Jeffrey A; Cheetham, Janet; Croghan, Michael; Doherty, Elizabeth M; Hale, Clarence; Jarosinski, Mark A; Kelly, Michael G; Norman, Mark H; Tamayo, Nuria A; Xi, Ning; Baumgartner, James W

2003-07-21

The solution structure of a potent melanocortin receptor agonist, Ac-Nle-cyclo[Asp-Pro-DPhe-Arg-Trp-Lys]-NH(2) (1) was calculated using distance restraints determined from 1H NMR spectroscopy. Eight of the lowest energy conformations from this study were used to identify non-peptide cores that mimic the spatial arrangement of the critical tripeptide region, DPhe-Arg-Trp, found in 1. From these studies, compound 2a, containing the cis-cyclohexyl core, was identified as a functional agonist of the melanocortin-4 receptor (MC4R) with an IC(50) and EC(50) below 10 nM. Compound 2a also showed 36- and 7-fold selectivity over MC3R and MC1R, respectively, in the binding assays. Subtle changes in cyclohexane stereochemistry and removal of functional groups led to analogues with lower affinity for the MC receptors.

Switch from antagonist to agonist after addition of a DOTA chelator to a somatostatin analog

International Nuclear Information System (INIS)

Reubi, Jean Claude; Cescato, Renzo; Waser, Beatrice; Erchegyi, Judit; Rivier, Jean E.

2010-01-01

Peptide receptor targeting has become an increasingly attractive method to target tumors diagnostically and radiotherapeutically. Peptides linked to a variety of chelators have been developed for this purpose. They have, however, rarely been tested for their agonistic or antagonistic properties. We report here on a somatostatin antagonist that switched to an agonist upon coupling to a DOTA chelator. Two novel somatostatin analogs, 406-040-15 and its DOTA-coupled counterpart 406-051-20, with and without cold Indium labeling, were tested for their somatostatin receptor subtypes 1-5 (sst 1 -sst 5 ) binding affinity using receptor autoradiography. Moreover, they were tested functionally for their ability to affect sst 2 and sst 3 internalization in vitro in HEK293 cells stably expressing the human sst 2 or sst 3 receptor, using an immunofluorescence microscopy-based internalization assay. All three compounds were characterized as pan-somatostatin analogs having a high affinity for all five sst. In the sst 2 internalization assay, all three compounds showed an identical behavior, namely, a weak agonistic effect complemented by a weak antagonistic effect, compatible with the behavior of a partial agonist. Conversely, in the sst 3 internalization assay, 406-040-15 was a full antagonist whereas its DOTA-coupled counterpart, 406-051-20, with and without Indium labeling, switched to a full agonist. Adding the DOTA chelator to the somatostatin analog 406-040-15 triggers a switch at sst 3 receptor from an antagonist to an agonist. This indicates that potential radioligands for tumor targeting should always be tested functionally before further development, in particular if a chelator is added. (orig.)

Design and evaluation of antimalarial peptides derived from prediction of short linear motifs in proteins related to erythrocyte invasion.

Directory of Open Access Journals (Sweden)

Alessandra Bianchin

Full Text Available The purpose of this study was to investigate the blood stage of the malaria causing parasite, Plasmodium falciparum, to predict potential protein interactions between the parasite merozoite and the host erythrocyte and design peptides that could interrupt these predicted interactions. We screened the P. falciparum and human proteomes for computationally predicted short linear motifs (SLiMs in cytoplasmic portions of transmembrane proteins that could play roles in the invasion of the erythrocyte by the merozoite, an essential step in malarial pathogenesis. We tested thirteen peptides predicted to contain SLiMs, twelve of them palmitoylated to enhance membrane targeting, and found three that blocked parasite growth in culture by inhibiting the initiation of new infections in erythrocytes. Scrambled peptides for two of the most promising peptides suggested that their activity may be reflective of amino acid properties, in particular, positive charge. However, one peptide showed effects which were stronger than those of scrambled peptides. This was derived from human red blood cell glycophorin-B. We concluded that proteome-wide computational screening of the intracellular regions of both host and pathogen adhesion proteins provides potential lead peptides for the development of anti-malarial compounds.

Recent Advances in GLP-1 Receptor Agonists for Use in Diabetes Mellitus.

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McBrayer, Dominic N; Tal-Gan, Yftah

2017-09-01

Preclinical Research Mimetics of Glucagon-like peptide 1 (GLP-1) represent a useful alternative or complementary treatment choice to insulin in the treatment of diabetes mellitus. The lack of hypoglycemia as a side effect when GLP-1 receptor agonists are used along with the tendency of these therapeutic agents to prevent or even reduce weight gain makes them valuable targets in therapy development. However, native GLP-1 and many of its early analogues have very short half-lives, requiring repeated treatment to maintain therapeutic levels. As all current treatments are injected subcutaneously, a large focus has been made on trying to extend the half-lives of GLP-1 analogues while retaining bioactivity. Most success in this regard has been achieved with the use of peptide-protein fusions, which are not as well suited for oral administration. However, recent work focused on the development of non-fusion peptides with increased half-lives that may be more appropriate for oral administration. This minireview discusses the structural characteristics of past and present analogues as well as the recent work conducted toward developing novel GLP-1 receptor agonists. Drug Dev Res 78 : 292-299, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Peptide drugs to target G protein-coupled receptors.

Science.gov (United States)

Bellmann-Sickert, Kathrin; Beck-Sickinger, Annette G

2010-09-01

Major indications for use of peptide-based therapeutics include endocrine functions (especially diabetes mellitus and obesity), infectious diseases, and cancer. Whereas some peptide pharmaceuticals are drugs, acting as agonists or antagonists to directly treat cancer, others (including peptide diagnostics and tumour-targeting pharmaceuticals) use peptides to 'shuttle' a chemotherapeutic agent or a tracer to the tumour and allow sensitive imaging or targeted therapy. Significant progress has been made in the last few years to overcome disadvantages in peptide design such as short half-life, fast proteolytic cleavage, and low oral bioavailability. These advances include peptide PEGylation, lipidisation or multimerisation; the introduction of peptidomimetic elements into the sequences; and innovative uptake strategies such as liposomal, capsule or subcutaneous formulations. This review focuses on peptides targeting G protein-coupled receptors that are promising drug candidates or that have recently entered the pharmaceutical market. Copyright 2010 Elsevier Ltd. All rights reserved.

Glucagon-like peptide 1 receptor agonists: a new approach to type 2 ...

African Journals Online (AJOL)

Hypoglycaemia and weight gain that are associated with many antidiabetic medications may interfere with the implementation and long-term application of treatment strategies. Glucose homeostasis is dependent on a complex interplay of multiple hormones and gastrointestinal peptides, including glucagon-like peptide 1 ...

γ-Preprotachykinin-(72-92)-peptide amide: An endogenous preprotachykinin I gene-derived peptide that preferentially binds to neurokinin-2 receptors

International Nuclear Information System (INIS)

Dam, T.V.; Takeda, Y.; Krause, J.E.; Escher, E.; Quirion, R.

1990-01-01

The presence of N-terminally extended forms of neurokinin A has recently been reported in the mammalian brain. Among them, gamma-preprotachykinin-(72-92)-peptide amide [gamma-PPT-(72-92)-NH2], a peptide derived by posttranslational processing of gamma-preprotachykinin, is most prominent. We report here that this peptide most likely acts on neurokinin-2 receptor sites since neurokinin A (a putative neurokinin-2 agonist) and gamma-PPT-(72-92)-NH2 are potent competitors of 125I-labeled gamma-PPT-(72-92)-NH2 binding whereas selective neurokinin-1 and -3 agonists are not. Moreover, the distribution of 125I-labeled gamma-PPT-(72-92)-NH2 and 125I-labeled neurokinin A binding sites are very similar in rat brain. On the other hand, 125I-labeled Bolton-Hunter-substance P (a neurokinin-1 ligand) and 125I-labeled Bolton-Hunter-eledoisin (a neurokinin-3 ligand) binding sites are differentially located in this tissue. Thus, it appears that gamma-PPT-(72-92)-NH2 binds to neurokinin-2 receptors and should be considered as a putative endogenous ligand for this receptor class

Lixisenatide, a novel GLP-1 receptor agonist for the treatment of type 2 diabetes mellitus

DEFF Research Database (Denmark)

Christensen, Mikkel; Knop, Filip K; Holst, Jens J

2009-01-01

Lixisenatide, under development by sanofi-aventis, is a novel human glucagon-like peptide-1 receptor (GLP-1R) agonist for the treatment of type 2 diabetes mellitus (T2DM; non-insulin dependent diabetes). The structure of lixisenatide, based on exendin-4(1-39) modified C-terminally with six Lys...... of the anticipated effects of lixisenatide on glycemic measures and weight; favorable results would place lixisenatide for consideration among other GLP-1R agonists in the treatment armamentarium for T2DM....

Patients with Obesity Caused by Melanocortin-4 Receptor Mutations Can Be Treated with a Glucagon-like Peptide-1 Receptor Agonist

DEFF Research Database (Denmark)

Iepsen, Eva W; Zhang, Jinyi; Thomsen, Henrik S

2018-01-01

Pathogenic mutations in the appetite-regulating melanocortin-4 receptor (MC4R) represent the most common cause of monogenic obesity with limited treatment options. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) cause weight loss by reducing appetite. We assessed the effect of the GLP-1 RA...... liraglutide 3.0 mg for 16 weeks in 14 obese individuals with pathogenic MC4R mutations (BMI 37.5 ± 6.8) and 28 matched control participants without MC4R mutation (BMI 36.8 ± 4.8). Liraglutide decreased body weight by 6.8 kg ± 1.8 kg in individuals with pathogenic MC4R mutations and by 6.1 kg ± 1.2 kg...... in control participants. Total body fat, waist circumference, and fasting and postprandial glucose concentrations similarly decreased in both groups. Thus, liraglutide induced an equal, clinically significant weight loss of 6% in both groups, indicating that the appetite-reducing effect of liraglutide...

Dipeptidyl peptidase-4 (DPP-4) inhibitors are favourable to glucagon-like peptide-1 (GLP-1) agonists

DEFF Research Database (Denmark)

Madsbad, Sten

2012-01-01

Incretin-based therapies, which include the GLP-1 receptor agonists and DPP-4 inhibitors, use the antidiabetic properties of potentiating the GLP-1 receptor signalling via the regulation of insulin and glucagon secretion, inhibition of gastric emptying and suppression of appetite. Most physicians...... will start antidiabetic treatment with metformin, but adding a GLP-1 receptor agonist as the second drug seems to be optimal since more patients will reach an HbA1c below 7% than with a DPP-4 inhibitor or another oral antidiabetic agents and with minimal risk of hypoglycaemia. The GLP-1 receptor agonists...

Comparison of Linear and Cyclic His-Ala-Val Peptides in Modulating the Blood-Brain Barrier Permeability: Impact on Delivery of Molecules to the Brain.

Science.gov (United States)

Alaofi, Ahmed; On, Ngoc; Kiptoo, Paul; Williams, Todd D; Miller, Donald W; Siahaan, Teruna J

2016-02-01

The aim of this study is to evaluate the effect of peptide cyclization on the blood-brain barrier (BBB) modulatory activity and plasma stability of His-Ala-Val peptides, which are derived from the extracellular 1 domain of human E-cadherin. The activities to modulate the intercellular junctions by linear HAV4 (Ac-SHAVAS-NH2), cyclic cHAVc1 (Cyclo(1,8)Ac-CSHAVASC-NH2), and cyclic cHAVc3 (Cyclo(1,6)Ac-CSHAVC-NH2) were compared in in vitro and in vivo BBB models. Linear HAV4 and cyclic cHAVc1 have the same junction modulatory activities as assessed by in vitro MDCK monolayer model and in situ rat brain perfusion model. In contrast, cyclic cHAVc3 was more effective than linear HAV4 in modulating MDCK cell monolayers and in improving in vivo brain delivery of Gd-DTPA on i.v. administration in Balb/c mice. Cyclic cHAVc3 (t1/2 = 12.95 h) has better plasma stability compared with linear HAV4 (t1/2 = 2.4 h). The duration of the BBB modulation was longer using cHAVc3 (2-4 h) compared with HAV4 (brain delivery of IRdye800cw-PEG (25 kDa) as detected by near IR imaging. The result showed that cyclic cHAVc3 peptide had better activity and plasma stability than linear HAV4 peptide. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Superior reductions in hepatic steatosis and fibrosis with co-administration of a glucagon-like peptide-1 receptor agonist and obeticholic acid in mice.

Science.gov (United States)

Jouihan, Hani; Will, Sarah; Guionaud, Silvia; Boland, Michelle L; Oldham, Stephanie; Ravn, Peter; Celeste, Anthony; Trevaskis, James L

2017-11-01

Nonalcoholic steatohepatitis (NASH) is an unmet need associated with metabolic syndrome. There are no approved therapies for NASH; however, glucagon-like peptide-1 receptor (GLP-1R) and farnesoid-X receptor (FXR) agonists are promising drug targets. We investigated the therapeutic effects of co-administration of a GLP-1R agonist, IP118, with FXR agonist obeticholic acid (OCA) in mice. OCA and IP118 alone and in combination were sub-chronically administered to Lep ob /Lep ob mice with diet-induced NASH or diet-induced obese (DIO) mice. Metabolic (body weight and glucose) and liver (biochemical and histological) endpoints were assessed. NASH severity in Lep ob /Lep ob mice was graded using a customized integrated scoring system. OCA reduced liver weight and lipid in NASH mice (both by -17%) but had no effect on plasma ALT or AST levels. In contrast, IP118 significantly reduced liver weight (-21%), liver lipid (-15%), ALT (-29%), and AST (-27%). The combination of OCA + IP118 further reduced liver weight (-29%), liver lipid (-22%), ALT (-39%), and AST (-36%). Combination therapy was superior to monotherapies in reducing hepatic steatosis, inflammation, and fibrosis. Hepatic improvements with IP118 and OCA + IP118 were associated with reduced body weight (-4.3% and -3.5% respectively) and improved glycemic control in OCA + IP118-treated mice. In DIO mice, OCA + IP118 co-administration reduced body weight (-25.3%) to a greater degree than IP118 alone (-12.5%) and further improved glucose tolerance and reduced hepatic lipid. Our data suggest a complementary or synergistic therapeutic effect of GLP-1R and FXR agonism in mouse models of metabolic disease and NASH. Copyright © 2017 The Authors. Published by Elsevier GmbH.. All rights reserved.

GLP-1 agonists for type 2 diabetes

DEFF Research Database (Denmark)

Jespersen, Maria J; Knop, Filip K; Christensen, Mikkel

2013-01-01

and legal documents in the form of assessment reports from the European Medicines Agency and the United States Food and Drug Administration. EXPERT OPINION: GLP-1-based therapy combines several unique mechanisms of action and have the potential to gain widespread use in the fight against diabetes......Within recent years, glucagon-like peptide 1 receptor agonists (GLP-1-RA) have emerged as a new treatment option for type 2 diabetes. The GLP-1-RA are administered subcutaneously and differ substantially in pharmacokinetic profiles. AREAS COVERED: This review describes the pharmacokinetics...

Effects of gastric inhibitory polypeptide, glucagon-like peptide-1 and glucagon-like peptide-1 receptor agonists on Bone Cell Metabolism.

Science.gov (United States)

Hansen, Morten S S; Tencerova, Michaela; Frølich, Jacob; Kassem, Moustapha; Frost, Morten

2018-01-01

The relationship between gut and skeleton is increasingly recognized as part of the integrated physiology of the whole organism. The incretin hormones gastric inhibitory polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are secreted from the intestine in response to nutrient intake and exhibit several physiological functions including regulation of islet hormone secretion and glucose levels. A number of GLP-1 receptor agonists (GLP-1RAs) are currently used in treatment of type 2 diabetes and obesity. However, GIP and GLP-1 cognate receptors are widely expressed suggesting that incretin hormones mediate effects beyond control of glucose homeostasis, and reports on associations between incretin hormones and bone metabolism have emerged. The aim of this MiniReview was to provide an overview of current knowledge regarding the in vivo and in vitro effects of GIP and GLP-1 on bone metabolism. We identified a total of 30 pre-clinical and clinical investigations of the effects of GIP, GLP-1 and GLP-1RAs on bone turnover markers, bone mineral density (BMD), bone microarchitecture and fracture risk. Studies conducted in cell cultures and rodents demonstrated that GIP and GLP-1 play a role in regulating skeletal homeostasis, with pre-clinical data suggesting that GIP inhibits bone resorption whereas GLP-1 may promote bone formation and enhance bone material properties. These effects are not corroborated by clinical studies. While there is evidence of effects of GIP and GLP-1 on bone metabolism in pre-clinical investigations, clinical trials are needed to clarify whether similar effects are present and clinically relevant in humans. © 2017 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).

Computer-Aided Design of Antimicrobial Peptides

DEFF Research Database (Denmark)

Fjell, Christopher D.; Hancock, Robert E.W.; Jenssen, Håvard

2010-01-01

in antimicrobial activity. Consequently, the majority of peptides put into clinical trials have failed at some point, underlining the importance of a thorough peptide optimization. An important tool in peptide design and optimization is quantitative structure-activity relationship (QSAR) analysis, correlating...... chemical parameters with biological activities of the peptide, using statistical methods. In this review we will discuss two different in silico strategies of computer-aided antibacterial peptide design, a linear correlation model build as an extension of traditional principal component analysis (PCA......) and a non-linear artificial neural network model. Studies on structurally diverse peptides, have concluded that the PCA derived model are able to guide the antibacterial peptide design in a meaningful way, however requiring rather a high homology between the peptides in the test-set and the in silico...

Generalized concentration addition: a method for examining mixtures containing partial agonists.

Science.gov (United States)

Howard, Gregory J; Webster, Thomas F

2009-08-07

Environmentally relevant toxic exposures often consist of simultaneous exposure to multiple agents. Methods to predict the expected outcome of such combinations are critical both to risk assessment and to an accurate judgment of whether combinations are synergistic or antagonistic. Concentration addition (CA) has commonly been used to assess the presence of synergy or antagonism in combinations of similarly acting chemicals, and to predict effects of combinations of such agents. CA has the advantage of clear graphical interpretation: Curves of constant joint effect (isoboles) must be negatively sloped straight lines if the mixture is concentration additive. However, CA cannot be directly used to assess combinations that include partial agonists, although such agents are of considerable interest. Here, we propose a natural extension of CA to a functional form that may be applied to mixtures including full agonists and partial agonists. This extended definition, for which we suggest the term "generalized concentration addition," encompasses linear isoboles with slopes of any sign. We apply this approach to the simple example of agents with dose-response relationships described by Hill functions with slope parameter n=1. The resulting isoboles are in all cases linear, with negative, zero and positive slopes. Using simple mechanistic models of ligand-receptor systems, we show that the same isobole pattern and joint effects are generated by modeled combinations of full and partial agonists. Special cases include combinations of two full agonists and a full agonist plus a competitive antagonist.

Biologically relevant conformational features of linear and cyclic proteolipid protein (PLP) peptide analogues obtained by high-resolution nuclear magnetic resonance and molecular dynamics

Science.gov (United States)

Kordopati, Golfo G.; Tzoupis, Haralambos; Troganis, Anastassios N.; Tsivgoulis, Gerasimos M.; Golic Grdadolnik, Simona; Simal, Carmen; Tselios, Theodore V.

2017-09-01

Proteolipid protein (PLP) is one of the main proteins of myelin sheath that are destroyed during the progress of multiple sclerosis (MS). The immunodominant PLP139-151 epitope is known to induce experimental autoimmune encephalomyelitis (EAE, animal model of MS), wherein residues 144 and 147 are recognized by T cell receptor (TCR) during the formation of trimolecular complex with peptide-antigen and major histocompability complex. The conformational behavior of linear and cyclic peptide analogues of PLP, namely PLP139-151 and cyclic (139-151) (L144, R147) PLP139-151, have been studied in solution by means of nuclear magnetic resonance (NMR) methods in combination with unrestrained molecular dynamics simulations. The results indicate that the side chains of mutated amino acids in the cyclic analogue have different spatial orientation compared with the corresponding side chains of the linear analogue, which can lead to reduced affinity to TCR. NMR experiments combined with theoretical calculations pave the way for the design and synthesis of potent restricted peptides of immunodominant PLP139-151 epitope as well as non peptide mimetics that rises as an ultimate goal.

PARTIAL AGONISTS, FULL AGONISTS, ANTAGONISTS - DILEMMAS OF DEFINITION

NARCIS (Netherlands)

HOYER, D; BODDEKE, HWGM

The absence of selective antagonists makes receptor characterization difficult, and largely dependent on the use of agonists. However, there has been considerable debate as to whether certain drugs acting at G protein-coupled receptors are better described as agonists, partial agonists or

Effects of insulin analogs and glucagon-like peptide-1 receptor agonists on proliferation and cellular energy metabolism in papillary thyroid cancer

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He L

2017-11-01

Full Text Available Liang He,1,* Siliang Zhang,2,* Xiaowen Zhang,3 Rui Liu,2 Haixia Guan,2 Hao Zhang1 1Department of Thyroid Surgery, The First Hospital of China Medical University, Shenyang, Liaoning, 2Department of Endocrinology and Metabolism, The Endocrine Institute and The Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Hospital of China Medical University, Shenyang, Liaoning, 3Department of Endocrinology and Metabolism, Drum Tower Hospital Affiliated to Nanjing University Medical School, Nanjing, People’s Republic of China *These authors contributed equally to this work Purpose: This study was aimed to investigate the expressions of the insulin receptor (IR, insulin-like growth factor receptor (IGF-1R, and glucagon-like peptide-1 receptor (GLP-1R in normal thyroid tissue, papillary thyroid cancer (PTC tissues, and PTC cells, and to examine the possible role of insulin analogs and GLP-1R agonists in cell proliferation and energy metabolism in PTC cells.Methods: The expressions of IR, IGF-1R, and GLP-1R in PTC tissues and PTC cell lines were detected by immunohistochemistry and western blotting, respectively. Cell proliferation was evaluated by the 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide assay. Levels of members of the phosphoinositol-3 kinase/AKT serine/threonine kinase (Akt and mitogen-activated protein kinase/extracellular signal-regulated kinase (Erk signaling pathways were measured by western blotting. Energy metabolism of PTC cell lines was analyzed using a Seahorse Extracellular Flux analyzer.Results: Three receptors could be detected in both PTC tissues and PTC cell lines. Expressions of IGF-1R and GLP-1R were more obvious in PTC than in normal thyroid cells. Neither insulin, four insulin analogs, and two GLP-1R agonists showed significant effects on the proliferation of PTC cells, nor did they influence the levels of Akt/p-Akt and Erk/p-Erk. None of these antidiabetic agents could change the mitochondrial

The cytoplasmic domain close to the transmembrane region of the glucagon-like peptide-1 receptor contains sequence elements that regulate agonist-dependent internalisation.

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Vázquez, Patricia; Roncero, Isabel; Blázquez, Enrique; Alvarez, Elvira

2005-07-01

In order to gain better insight into the molecular events involved in the signal transduction generated through glucagon-like peptide-1 (GLP-1) receptors, we tested the effect of deletions and point mutations within the cytoplasmic tail of this receptor with a view to establishing relationships between signal transduction desensitisation and receptor internalisation. Wild-type and truncated (deletion of the last 27 amino acids (GLPR 435R) and deletion of 44 amino acids (GLPR 418R)) GLP-1 receptors bound the agonist with similar affinity. Deletion of the last 27 amino acids decreased the internalisation rate by 78%, while deletion of 44 amino acids containing all the phosphorylation sites hitherto described in this receptor decreased the internalisation rate by only 47%. Binding of the ligand to both receptors stimulated adenylyl cyclase. In contrast, deletion of the region containing amino acids 419 to 435 (GLPR 419delta435) increased the internalisation rate by 268%, and the replacement of EVQ(408-410) by alanine (GLPR A(408-410)) increased this process to 296%. In both receptors, the efficacy in stimulating adenylate cyclase was decreased. All the receptors studied were internalised by coated pits, except for the receptor with a deletion of the last 44 amino acids, which also had a faster resensitisation rate. Our findings indicate that the neighbouring trans-membrane domain of the carboxyl-terminal tail of the GLP-1 receptor contains sequence elements that regulate agonist-dependent internalisation and transmembrane signalling.

Glucagon-Like Peptide-1 Receptor Agonists for the Treatment of Type 2 Diabetes Mellitus: A Position Statement of the Korean Diabetes Association.

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Kim, Hyun Jin; Park, Seok O; Ko, Seung Hyun; Rhee, Sang Youl; Hur, Kyu Yeon; Kim, Nan Hee; Moon, Min Kyong; Lee, Byung Wan; Kim, Jin Hwa; Choi, Kyung Mook

2017-12-01

The glucagon-like peptide-1 receptor agonists (GLP-1RAs) were recommended as a monotherapy or combination therapy with oral hypoglycemic agents or basal insulin in the position statement of the Korean Diabetes Association 2017 for pharmacological therapy. Many randomized clinical trials and systematic reviews report that GLP-1RAs have considerable glucose-lowering effect and lead to weight reduction and low risk of hypoglycemia when used as a monotherapy or combination therapy. The cardiovascular safety of GLP-1RAs has been assessed in several randomized clinical trials and systematic reviews. The results of cardiovascular outcome trials of long-acting GLP-1RAs (liraglutide, semaglutide) demonstrated cardiovascular benefits in subjects with type 2 diabetes mellitus and a high risk of cardiovascular disease. The GLP-1RA may be a choice of therapy when weight control and avoidance of hypoglycemia are important, and patients with high risk of cardiovascular disease might also favor choosing GLP-1RA. Copyright © 2017 Korean Diabetes Association.

Glucagon-Like Peptide-1 Receptor Agonists for the Treatment of Type 2 Diabetes Mellitus: A Position Statement of the Korean Diabetes Association

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Hyun Jin Kim

2017-12-01

Full Text Available The glucagon-like peptide-1 receptor agonists (GLP-1RAs were recommended as a monotherapy or combination therapy with oral hypoglycemic agents or basal insulin in the position statement of the Korean Diabetes Association 2017 for pharmacological therapy. Many randomized clinical trials and systematic reviews report that GLP-1RAs have considerable glucose-lowering effect and lead to weight reduction and low risk of hypoglycemia when used as a monotherapy or combination therapy. The cardiovascular safety of GLP-1RAs has been assessed in several randomized clinical trials and systematic reviews. The results of cardiovascular outcome trials of long-acting GLP-1RAs (liraglutide, semaglutide demonstrated cardiovascular benefits in subjects with type 2 diabetes mellitus and a high risk of cardiovascular disease. The GLP-1RA may be a choice of therapy when weight control and avoidance of hypoglycemia are important, and patients with high risk of cardiovascular disease might also favor choosing GLP-1RA.

GLP-1 receptor agonists in the treatment of polycystic ovary syndrome.

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Lamos, Elizabeth Mary; Malek, Rana; Davis, Stephen N

2017-04-01

Polycystic ovarian syndrome (PCOS) affects many women of child-bearing age and is characterized by hyperandrogenism, ovulatory and metabolic dysfunction. A primary treatment goal is weight reduction. The weight loss effects of glucagon-like peptide-1 receptor agonists (GLP-1RA), previously demonstrated in diabetic and obese non-diabetic patients, offer a unique opportunity to expand the medical options available to PCOS patients. Areas covered: Available clinical trials of glucagon-like peptide-1 receptor agonist therapy in PCOS were reviewed. Literature was searched from PubMed using appropriate search terms up to November 2016. Expert commentary: The available studies of GLP-1 RA therapy in the treatment of excess body weight in women with PCOS demonstrate that exenatide and liraglutide are effective in weight reduction either as monotherapy or in combination with metformin. A few studies showed that androgens may be modestly decreased and menstrual frequency may be increased. Eating behavior may be improved with liraglutide therapy. Glucose parameters are generally improved. GLP-1RAs were well-tolerated, with nausea being the most significant adverse side effect. Barriers to utilization may be the short duration studies, lack of familiarity of the medication, the route of administration (injection) and the variable outcomes on ovulation and hyperandrogenism.

Glucagon-like peptide-1 receptor agonists in the treatment of type 2 diabetes: Past, present, and future

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Sanjay Kalra

2016-01-01

Full Text Available Glucagon-like peptide-1 (GLP-1–based therapy improves glycaemic control through multiple mechanisms, with a low risk of hypoglycaemia and the additional benefit of clinically relevant weight loss. Since Starling and Bayliss first proposed the existence of intestinal secretions that stimulate the pancreas, tremendous progress has been made in the area of incretins. As a number of GLP-1 receptor agonists (GLP-1 RAs continue to become available, physicians will soon face the challenge of selecting the right option customized to their patient's needs. The following discussion, derived from an extensive literature search using the PubMed database, applying the terms incretin, GLP-1, exenatide, liraglutide, albiglutide, dulaglutide, lixisenatide, semaglutide, and taspoglutide, provides a comprehensive review of existing and upcoming molecules in the GLP-1 RA class in terms of their structure, pharmacological profiles, efficacy, safety, and convenience. Search Methodology: A literature search was conducted using the PubMed database, applying the terms incretin, GLP-1, exenatide, liraglutide, albiglutide, dulaglutide, lixisenatide, semaglutide, and taspoglutide. Relevant articles were those that discussed structural, pharmacokinetic and pharmacodynamic differences, classification, long-acting and short-acting GLP-1 RAs, phase 3 trials, and expert opinions. Additional targeted searches were conducted on diabetes treatment guidelines and reviews on safety, as well as the American Diabetes Association/European Society for Study of Diabetes (ADA/EASD statement on pancreatic safety.

Structure-activity relationships of the unique and potent agouti-related protein (AGRP)-melanocortin chimeric Tyr-c[beta-Asp-His-DPhe-Arg-Trp-Asn-Ala-Phe-Dpr]-Tyr-NH2 peptide template.

Science.gov (United States)

Wilczynski, Andrzej; Wilson, Krista R; Scott, Joseph W; Edison, Arthur S; Haskell-Luevano, Carrie

2005-04-21

The melanocortin receptor system consists of endogenous agonists, antagonists, G-protein coupled receptors, and auxiliary proteins that are involved in the regulation of complex physiological functions such as energy and weight homeostasis, feeding behavior, inflammation, sexual function, pigmentation, and exocrine gland function. Herein, we report the structure-activity relationship (SAR) of a new chimeric hAGRP-melanocortin agonist peptide template Tyr-c[beta-Asp-His-DPhe-Arg-Trp-Asn-Ala-Phe-Dpr]-Tyr-NH(2) that was characterized using amino acids previously reported in other melanocortin agonist templates. Twenty peptides were examined in this study, and six peptides were selected for (1)H NMR and computer-assisted molecular modeling structural analysis. The most notable results include the identification that modification of the chimeric template at the His position with Pro and Phe resulted in ligands that were nM mouse melanocortin-3 receptor (mMC3R) antagonists and nM mouse melanocortin-4 receptor (mMC4R) agonists. The peptides Tyr-c[beta-Asp-His-DPhe-Ala-Trp-Asn-Ala-Phe-Dpr]-Tyr-NH(2) and Tyr-c[beta-Asp-His-DNal(1')-Arg-Trp-Asn-Ala-Phe-Dpr]-Tyr-NH(2) resulted in 730- and 560-fold, respectively, mMC4R versus mMC3R selective agonists that also possessed nM agonist potency at the mMC1R and mMC5R. Structural studies identified a reverse turn occurring in the His-DPhe-Arg-Trp domain, with subtle differences observed that may account for the differences in melanocortin receptor pharmacology. Specifically, a gamma-turn secondary structure involving the DPhe(4) in the central position of the Tyr-c[beta-Asp-Phe-DPhe-Arg-Trp-Asn-Ala-Phe-Dpr]-Tyr-NH(2) peptide may differentiate the mixed mMC3R antagonist and mMC4R agonist pharmacology.

Neurogenic and neurotrophic effects of BDNF peptides in mouse hippocampal primary neuronal cell cultures.

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Maria del Carmen Cardenas-Aguayo

Full Text Available The level of brain-derived neurotrophic factor (BDNF, a member of the neurotrophin family, is down regulated in Alzheimer's disease (AD, Parkinson's disease (PD, depression, stress, and anxiety; conversely the level of this neurotrophin is increased in autism spectrum disorders. Thus, modulating the level of BDNF can be a potential therapeutic approach for nervous system pathologies. In the present study, we designed five different tetra peptides (peptides B-1 to B-5 corresponding to different active regions of BDNF. These tetra peptides were found to be non-toxic, and they induced the expression of neuronal markers in mouse embryonic day 18 (E18 primary hippocampal neuronal cultures. Additionally, peptide B-5 induced the expression of BDNF and its receptor, TrkB, suggesting a positive feedback mechanism. The BDNF peptides induced only a moderate activation (phosphorylation at Tyr 706 of the TrkB receptor, which could be blocked by the Trk's inhibitor, K252a. Peptide B-3, when combined with BDNF, potentiated the survival effect of this neurotrophin on H(2O(2-treated E18 hippocampal cells. Peptides B-3 and B-5 were found to work as partial agonists and as partial antagonists competing with BDNF to activate the TrkB receptor in a dose-dependent manner. Taken together, these results suggest that the described BDNF tetra peptides are neurotrophic, can modulate BDNF signaling in a partial agonist/antagonist way, and offer a novel therapeutic approach to neural pathologies where BDNF levels are dysregulated.

Exendin-4, a glucagon-like peptide 1 receptor agonist, protects against amyloid-β peptide-induced impairment of spatial learning and memory in rats.

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Jia, Xiao-Tao; Ye-Tian; Yuan-Li; Zhang, Ge-Juan; Liu, Zhi-Qin; Di, Zheng-Li; Ying, Xiao-Ping; Fang, Yan; Song, Er-Fei; Qi, Jin-Shun; Pan, Yan-Fang

2016-05-15

Type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD) share specific molecular mechanisms, and agents with proven efficacy in one may be useful against the other. The glucagon-like peptide-1 (GLP-1) receptor agonist exendin-4 has similar properties to GLP-1 and is currently in clinical use for T2DM treatment. Thus, this study was designed to characterize the effects of exendin-4 on the impairment of learning and memory induced by amyloid protein (Aβ) and its probable molecular underlying mechanisms. The results showed that (1) intracerebroventricular (i.c.v.) injection of Aβ1-42 resulted in a significant decline of spatial learning and memory of rats in water maze tests; (2) pretreatment with exendin-4 effectively and dose-dependently protected against the Aβ1-42-induced impairment of spatial learning and memory; (3) exendin-4 treatment significantly decreased the expression of Bax and cleaved caspase-3 and increased the expression of Bcl2 in Aβ1-42-induced Alzheimer's rats. The vision and swimming speed of the rats among all groups in the visible platform tests did not show any difference. These findings indicate that systemic pretreatment with exendin-4 can effectively prevent the behavioral impairment induced by neurotoxic Aβ1-42, and the underlying protective mechanism of exendin-4 may be involved in the Bcl2, Bax and caspase-3 pathways. Thus, the application of exendin-4 or the activation of its signaling pathways may be a promising strategy to ameliorate the degenerative processes observed in AD. Copyright © 2016 Elsevier Inc. All rights reserved.

Stereochemical studies of the monocyclic agouti-related protein (103-122) Arg-Phe-Phe residues: conversion of a melanocortin-4 receptor antagonist into an agonist and results in the discovery of a potent and selective melanocortin-1 agonist.

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Joseph, Christine G; Wang, Xiang S; Scott, Joseph W; Bauzo, Rayna M; Xiang, Zhimin; Richards, Nigel G; Haskell-Luevano, Carrie

2004-12-30

The agouti-related protein (AGRP) is an endogenous antagonist of the centrally expressed melanocortin receptors. The melanocortin-4 receptor (MC4R) is involved in energy homeostasis, food intake, sexual function, and obesity. The endogenous hAGRP protein is 132 amino acids in length, possesses five disulfide bridges at the C-terminus of the molecule, and is expressed in the hypothalamus of the brain. We have previously reported that a monocyclic hAGRP(103-122) peptide is an antagonist at the melanocortin receptors expressed in the brain. Stereochemical inversion from the endogenous l- to d-isomers of single or multiple amino acid modifications in this monocyclic truncated hAGRP sequence resulted in molecules that are converted from melanocortin receptor antagonists into melanocortin receptor agonists. The Asp-Pro-Ala-Ala-Thr-Ala-Tyr-cyclo[Cys-Arg-DPhe-DPhe-Asn-Ala-Phe-Cys]-Tyr-Ala-Arg-Lys-Leu peptide resulted in a 60 nM melanocortin-1 receptor agonist that is 100-fold selective versus the mMC4R, 1000-fold selective versus the mMC3R, and ca. 180-fold selective versus the mMC5R. In attempts to identify putative ligand-receptor interactions that may be participating in the agonist induced stimulation of the MC4R, selected ligands were docked into a homology molecular model of the mMC4R. These modeling studies have putatively identified hAGRP ligand DArg111-mMC4RAsn115 (TM3) and the hAGRP DPhe113-mMC4RPhe176 (TM4) interactions as important for agonist activity.

NKT-cell glycolipid agonist as adjuvant in synthetic vaccine.

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Liu, Zheng; Guo, Jun

2017-11-27

NKT cells are CD1d-restricted, glycolipid antigen-reactive, immunoregulatory T lymphocytes that can serve as a bridge between the innate and adaptive immunities. NKT cells have a wide range of therapeutic application in autoimmunity, transplant biology, infectious disease, cancer, and vaccinology. Rather than triggering "danger signal" and eliciting an innate immune response, αGalCer-based NKT-cell agonist act via a unique mechanism, recruiting NKT cells which play a T helper-like role even without peptide as Th epitope. Importantly, the non-polymorphism of CD1d render glycolipid a universal helper epitope, offering the potential to simplify the vaccine construct capable of eliciting consistent immune response in different individuals. This review details recent advances in the design of synthetic vaccines using NKT-cell agonist as adjuvant, highlighting the role of organic synthesis and conjugation technique to enhance the immunological actives and to simplify the vaccine constructs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Precision and linearity targets for validation of an IFNγ ELISPOT, cytokine flow cytometry, and tetramer assay using CMV peptides

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Lyerly Herbert K

2008-03-01

Full Text Available Abstract Background Single-cell assays of immune function are increasingly used to monitor T cell responses in immunotherapy clinical trials. Standardization and validation of such assays are therefore important to interpretation of the clinical trial data. Here we assess the levels of intra-assay, inter-assay, and inter-operator precision, as well as linearity, of CD8+ T cell IFNγ-based ELISPOT and cytokine flow cytometry (CFC, as well as tetramer assays. Results Precision was measured in cryopreserved PBMC with a low, medium, or high response level to a CMV pp65 peptide or peptide mixture. Intra-assay precision was assessed using 6 replicates per assay; inter-assay precision was assessed by performing 8 assays on different days; and inter-operator precision was assessed using 3 different operators working on the same day. Percent CV values ranged from 4% to 133% depending upon the assay and response level. Linearity was measured by diluting PBMC from a high responder into PBMC from a non-responder, and yielded R2 values from 0.85 to 0.99 depending upon the assay and antigen. Conclusion These data provide target values for precision and linearity of single-cell assays for those wishing to validate these assays in their own laboratories. They also allow for comparison of the precision and linearity of ELISPOT, CFC, and tetramer across a range of response levels. There was a trend toward tetramer assays showing the highest precision, followed closely by CFC, and then ELISPOT; while all three assays had similar linearity. These findings are contingent upon the use of optimized protocols for each assay.

Elabela/Toddler Is an Endogenous Agonist of the Apelin APJ Receptor in the Adult Cardiovascular System, and Exogenous Administration of the Peptide Compensates for the Downregulation of Its Expression in Pulmonary Arterial Hypertension.

Science.gov (United States)

Yang, Peiran; Read, Cai; Kuc, Rhoda E; Buonincontri, Guido; Southwood, Mark; Torella, Rubben; Upton, Paul D; Crosby, Alexi; Sawiak, Stephen J; Carpenter, T Adrian; Glen, Robert C; Morrell, Nicholas W; Maguire, Janet J; Davenport, Anthony P

2017-03-21

monocrotaline-exposed rats. These results show that ELA is an endogenous agonist of the human apelin receptor, exhibits a cardiovascular profile comparable to apelin, and is downregulated in human disease and rodent PAH models, and exogenous peptide can reduce the severity of cardiopulmonary remodeling and function in PAH in rats. This study provides additional proof of principle that an apelin receptor agonist may be of therapeutic use in PAH in humans. © 2017 The Authors.

The effect of various opiate receptor agonists on the seizure threshold in the rat. Is dynorphin an endogenous anticonvulsant?

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Przewłocka, B; Stala, L; Lasoń, W; Przewłocki, R

1983-01-01

The effects of various opiate receptor agonists on the seizure threshold after an intravenous infusion of pentylenetetrazol were investigated in rats. The mu- and epsilon-receptor agonists, morphine (20-40 micrograms) and beta-endorphin (5-10 micrograms) show proconvulsant properties towards clonic and tonic seizures. The delta-receptor agonist (D-Ala2,D-Leu5-enkephalin, DADL 5-40 micrograms) and alpha-neoendorphin (20-40 micrograms) show pro- and anticonvulsant properties towards clonic and tonic seizures, respectively. Anticonvulsant properties of DADL are possibly due to its action on the spinal cord, since after the intrathecal injection this effect is still observed. Similarities between DADL and alpha-neoendorphin suggest that they may act through the same receptor. The kappa-receptor agonist dynorphin A (5-20 micrograms) and its degradation-resistant analogue D-Arg-dynorphin1-13 (10 micrograms) show significant anticonvulsant properties. Our present results suggest that the kappa-receptor agonist dynorphin may act physiologically as an endogenous anticonvulsant, in contrast to other opioid peptides.

The angiotensin type 2 receptor agonist Compound 21 elicits cerebroprotection in endothelin-1 induced ischemic stroke

DEFF Research Database (Denmark)

Joseph, Jason P; Mecca, Adam P; Regenhardt, Robert W

2014-01-01

Evidence indicates that angiotensin II type 2 receptors (AT2R) exert cerebroprotective actions during stroke. A selective non-peptide AT2R agonist, Compound 21 (C21), has been shown to exert beneficial effects in models of cardiac and renal disease, as well as hemorrhagic stroke. Here, we hypothe...

Systematic discovery of new recognition peptides mediating protein interaction networks

DEFF Research Database (Denmark)

Neduva, Victor; Linding, Rune; Su-Angrand, Isabelle

2005-01-01

Many aspects of cell signalling, trafficking, and targeting are governed by interactions between globular protein domains and short peptide segments. These domains often bind multiple peptides that share a common sequence pattern, or "linear motif" (e.g., SH3 binding to PxxP). Many domains...... by interactions between globular protein domains and short peptide segments. These domains often bind multiple peptides that share a common sequence pattern, or "linear motif" (e.g., SH3 binding to PxxP). Many domains are known, though comparatively few linear motifs have been discovered. Their short length...

Do Neuroendocrine Peptides and Their Receptors Qualify as Novel Therapeutic Targets in Osteoarthritis?

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Susanne Grässel

2018-01-01

Full Text Available Joint tissues like synovium, articular cartilage, meniscus and subchondral bone, are targets for neuropeptides. Resident cells of these tissues express receptors for various neuroendocrine-derived peptides including proopiomelanocortin (POMC-derived peptides, i.e., α-melanocyte-stimulating hormone (α-MSH, adrenocorticotropin (ACTH and β-endorphin (β-ED, and sympathetic neuropeptides like vasoactive intestinal peptide (VIP and neuropeptide y (NPY. Melanocortins attained particular attention due to their immunomodulatory and anti-inflammatory effects in several tissues and organs. In particular, α-MSH, ACTH and specific melanocortin-receptor (MCR agonists appear to have promising anti-inflammatory actions demonstrated in animal models of experimentally induced arthritis and osteoarthritis (OA. Sympathetic neuropeptides have obtained increasing attention as they have crucial trophic effects that are critical for joint tissue and bone homeostasis. VIP and NPY are implicated in direct and indirect activation of several anabolic signaling pathways in bone and synovial cells. Additionally, pituitary adenylate cyclase-activating polypeptide (PACAP proved to be chondroprotective and, thus, might be a novel target in OA. Taken together, it appears more and more likely that the anabolic effects of these neuroendocrine peptides or their respective receptor agonists/antagonists may be exploited for the treatment of patients with inflammatory and degenerative joint diseases in the future.

SGLT2 inhibitors or GLP-1 receptor agonists as second-line therapy in type 2 diabetes: patient selection and perspectives.

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Gurgle, Holly E; White, Karen; McAdam-Marx, Carrie

2016-01-01

Controversy exists regarding the selection of second-line therapy for patients with type 2 diabetes mellitus (T2DM) who are unable to achieve glycemic control with metformin therapy alone. Newer pharmacologic treatments for T2DM include glucagon-like peptide-1 receptor agonists and sodium-glucose cotransporter 2 inhibitors. Both the classes of medication are efficacious, exhibit positive effects on weight, and are associated with minimal risk of hypoglycemia. The purpose of this review is to compare the clinical trial and real-world effectiveness data of glucagon-like peptide-1 receptor agonists versus sodium-glucose cotransporter 2 inhibitors related to A1c reduction, weight loss, cost-effectiveness, cardiovascular outcomes, and safety in patients with T2DM. This review summarizes comparative evidence for providers who are determining which of the two classes may be the most appropriate for a specific patient.

Molecular Characterisation of Small Molecule Agonists Effect on the Human Glucagon Like Peptide-1 Receptor Internalisation.

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Thompson, Aiysha; Stephens, Jeffrey W; Bain, Stephen C; Kanamarlapudi, Venkateswarlu

2016-01-01

The glucagon-like peptide receptor (GLP-1R), which is a G-protein coupled receptor (GPCR), signals through both Gαs and Gαq coupled pathways and ERK phosphorylation to stimulate insulin secretion. The aim of this study was to determine molecular details of the effect of small molecule agonists, compounds 2 and B, on GLP-1R mediated cAMP production, intracellular Ca2+ accumulation, ERK phosphorylation and its internalisation. In human GLP-1R (hGLP-1R) expressing cells, compounds 2 and B induced cAMP production but caused no intracellular Ca2+ accumulation, ERK phosphorylation or hGLP-1R internalisation. GLP-1 antagonists Ex(9-39) and JANT-4 and the orthosteric binding site mutation (V36A) in hGLP-1R failed to inhibit compounds 2 and B induced cAMP production, confirming that their binding site distinct from the GLP-1 binding site on GLP-1R. However, K334A mutation of hGLP-1R, which affects Gαs coupling, inhibited GLP-1 as well as compounds 2 and B induced cAMP production, indicating that GLP-1, compounds 2 and B binding induce similar conformational changes in the GLP-1R for Gαs coupling. Additionally, compound 2 or B binding to the hGLP-1R had significantly reduced GLP-1 induced intracellular Ca2+ accumulation, ERK phosphorylation and hGLP-1R internalisation. This study illustrates pharmacology of differential activation of GLP-1R by GLP-1 and compounds 2 and B.

Molecular Characterisation of Small Molecule Agonists Effect on the Human Glucagon Like Peptide-1 Receptor Internalisation.

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Aiysha Thompson

Full Text Available The glucagon-like peptide receptor (GLP-1R, which is a G-protein coupled receptor (GPCR, signals through both Gαs and Gαq coupled pathways and ERK phosphorylation to stimulate insulin secretion. The aim of this study was to determine molecular details of the effect of small molecule agonists, compounds 2 and B, on GLP-1R mediated cAMP production, intracellular Ca2+ accumulation, ERK phosphorylation and its internalisation. In human GLP-1R (hGLP-1R expressing cells, compounds 2 and B induced cAMP production but caused no intracellular Ca2+ accumulation, ERK phosphorylation or hGLP-1R internalisation. GLP-1 antagonists Ex(9-39 and JANT-4 and the orthosteric binding site mutation (V36A in hGLP-1R failed to inhibit compounds 2 and B induced cAMP production, confirming that their binding site distinct from the GLP-1 binding site on GLP-1R. However, K334A mutation of hGLP-1R, which affects Gαs coupling, inhibited GLP-1 as well as compounds 2 and B induced cAMP production, indicating that GLP-1, compounds 2 and B binding induce similar conformational changes in the GLP-1R for Gαs coupling. Additionally, compound 2 or B binding to the hGLP-1R had significantly reduced GLP-1 induced intracellular Ca2+ accumulation, ERK phosphorylation and hGLP-1R internalisation. This study illustrates pharmacology of differential activation of GLP-1R by GLP-1 and compounds 2 and B.

Structure-activity relationship of cyclic peptide penta-c[Asp-His(6)-DPhe(7)-Arg(8)-Trp(9)-Lys]-NH(2) at the human melanocortin-1 and -4 receptors: His(6) substitution.

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Cheung, Adrian Wai-Hing; Danho, Waleed; Swistok, Joseph; Qi, Lida; Kurylko, Grazyna; Rowan, Karen; Yeon, Mitch; Franco, Lucia; Chu, Xin-Jie; Chen, Li; Yagaloff, Keith

2003-04-07

A series of MT-II related cyclic peptides, based on potent but non-selective hMC4R agonist (Penta-c[Asp-His(6)-DPhe(7)-Arg(8)-Trp(9)-Lys]-NH(2)) was prepared in which His(6) residue was systematically substituted. Two of the most interesting peptides identified in this study are Penta-c[Asp-5-ClAtc-DPhe-Arg-Trp-Lys]-NH(2) and Penta-c[Asp-5-ClAtc-DPhe-Cit-Trp-Lys]-NH(2) which are potent hMC4R agonists and are either inactive or weak partial agonists (not tested for their antagonist activities) in hMC1R, hMC3R and hMC5R agonist assays.

SGLT2 inhibitors or GLP-1 receptor agonists as second-line therapy in type 2 diabetes: patient selection and perspectives

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Gurgle HE

2016-06-01

Full Text Available Holly E Gurgle, Karen White, Carrie McAdam-Marx Department of Pharmacotherapy, University of Utah College of Pharmacy, Salt Lake City, UT, USA Abstract: Controversy exists regarding the selection of second-line therapy for patients with type 2 diabetes mellitus (T2DM who are unable to achieve glycemic control with metformin therapy alone. Newer pharmacologic treatments for T2DM include glucagon-like peptide-1 receptor agonists and sodium–glucose cotransporter 2 inhibitors. Both the classes of medication are efficacious, exhibit positive effects on weight, and are associated with minimal risk of hypoglycemia. The purpose of this review is to compare the clinical trial and real-world effectiveness data of glucagon-like peptide-1 receptor agonists versus sodium–glucose cotransporter 2 inhibitors related to A1c reduction, weight loss, cost-effectiveness, cardiovascular outcomes, and safety in patients with T2DM. This review summarizes comparative evidence for providers who are determining which of the two classes may be the most appropriate for a specific patient. Keywords: type 2 diabetes mellitus, GLP-1 receptor agonist, SGLT2 inhibitor, A1c, weight loss, adverse effect

A pepducin derived from the third intracellular loop of FPR2 is a partial agonist for direct activation of this receptor in neutrophils but a full agonist for cross-talk triggered reactivation of FPR2.

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Michael Gabl

Full Text Available We recently described a novel receptor cross-talk mechanism in neutrophils, unique in that the signals generated by the PAF receptor (PAFR and the ATP receptor (P2Y2R transfer formyl peptide receptor 1 (FPR1 from a desensitized (non-signaling state back to an actively signaling state (Forsman H et al., PLoS One, 8:e60169, 2013; Önnheim K, et al., Exp Cell Res, 323∶209, 2014. In addition to the G-protein coupled FPR1, neutrophils also express the closely related receptor FPR2. In this study we used an FPR2 specific pepducin, proposed to work as an allosteric modulator at the cytosolic signaling interface, to determine whether the cross-talk pathway is utilized also by FPR2. The pepducin used contains a fatty acid linked to a peptide sequence derived from the third intracellular loop of FPR2, and it activates as well as desensensitizes this receptor. We now show that neutrophils desensitized with the FPR2-specific pepducin display increased cellular responses to stimulation with PAF or ATP. The secondary PAF/ATP induced response was sensitive to FPR2-specific inhibitors, disclosing a receptor cross-talk mechanism underlying FPR2 reactivation. The pepducin induced an activity in naïve cells similar to that of a conventional FPR2 agonist, but with lower potency (partial efficacy, meaning that the pepducin is a partial agonist. The PAF- or ATP-induced reactivation was, however, much more pronounced when neutrophils had been desensitized to the pepducin as compared to cells desensitized to conventional agonists. The pepducin should thus in this respect be classified as a full agonist. In summary, we demonstrate that desensitized FPR2 can be transferred back to an actively signaling state by receptor cross-talk signals generated through PAFR and P2Y2R, and the difference in agonist potency with respect to pepducin-induced direct receptor activation and cross-talk reactivation of FPR2 puts the concept of functional selectivity in focus.

Nanoparticulate STING agonists are potent lymph node-targeted vaccine adjuvants.

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Hanson, Melissa C; Crespo, Monica P; Abraham, Wuhbet; Moynihan, Kelly D; Szeto, Gregory L; Chen, Stephanie H; Melo, Mariane B; Mueller, Stefanie; Irvine, Darrell J

2015-06-01

Cyclic dinucleotides (CDNs) are agonists of stimulator of IFN genes (STING) and have potential as vaccine adjuvants. However, cyclic di-GMP (cdGMP) injected s.c. shows minimal uptake into lymphatics/draining lymph nodes (dLNs) and instead is rapidly distributed to the bloodstream, leading to systemic inflammation. Here, we encapsulated cdGMP within PEGylated lipid nanoparticles (NP-cdGMP) to redirect this adjuvant to dLNs. Compared with unformulated CDNs, encapsulation blocked systemic dissemination and markedly enhanced dLN accumulation in murine models. Delivery of NP-cdGMP increased CD8+ T cell responses primed by peptide vaccines and enhanced therapeutic antitumor immunity. A combination of a poorly immunogenic liposomal HIV gp41 peptide antigen and NP-cdGMP robustly induced type I IFN in dLNs, induced a greater expansion of vaccine-specific CD4+ T cells, and greatly increased germinal center B cell differentiation in dLNs compared with a combination of liposomal HIV gp41 and soluble CDN. Further, NP-cdGMP promoted durable antibody titers that were substantially higher than those promoted by the well-studied TLR agonist monophosphoryl lipid A and comparable to a much larger dose of unformulated cdGMP, without the systemic toxicity of the latter. These results demonstrate that nanoparticulate delivery safely targets CDNs to the dLNs and enhances the efficacy of this adjuvant. Moreover, this approach can be broadly applied to other small-molecule immunomodulators of interest for vaccines and immunotherapy.

Glutamate receptor agonists

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Vogensen, Stine Byskov; Greenwood, Jeremy R; Bunch, Lennart

2011-01-01

The neurotransmitter (S)-glutamate [(S)-Glu] is responsible for most of the excitatory neurotransmission in the central nervous system. The effect of (S)-Glu is mediated by both ionotropic and metabotropic receptors. Glutamate receptor agonists are generally a-amino acids with one or more...... stereogenic centers due to strict requirements in the agonist binding pocket of the activated state of the receptor. By contrast, there are many examples of achiral competitive antagonists. The present review addresses how stereochemistry affects the activity of glutamate receptor ligands. The review focuses...... mainly on agonists and discusses stereochemical and conformational considerations as well as biostructural knowledge of the agonist binding pockets, which is useful in the design of glutamate receptor agonists. Examples are chosen to demonstrate how stereochemistry not only determines how the agonist...

Liraglutide Versus Lixisenatide: Long-Term Cost-Effectiveness of GLP-1 Receptor Agonist Therapy for the Treatment of Type 2 Diabetes in Spain

OpenAIRE

Mezquita-Raya, Pedro; Ram?rez de Arellano, Antonio; Kragh, Nana; Vega-Hernandez, Gabriela; P?hlmann, Johannes; Valentine, William J.; Hunt, Barnaby

2017-01-01

Introduction Glucagon-like peptide-1 (GLP-1) receptor agonists are used successfully in the treatment of patients with type 2 diabetes as they are associated with low hypoglycemia rates, weight loss and improved glycemic control. This study compared, in the Spanish setting, the cost-effectiveness of liraglutide 1.8?mg versus lixisenatide 20??g, both GLP-1 receptor agonists, for patients with type 2 diabetes who had not achieved glycemic control targets on metformin monotherapy. Methods The IM...

Glucagon-Like Peptide-1 Receptor Agonist Use and Renal Impairment: A Retrospective Analysis of an Electronic Health Records Database in the U.S. Population.

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Boye, Kristina S; Botros, Fady T; Haupt, Axel; Woodward, Brad; Lage, Maureen J

2018-04-01

The study characterizes the use of glucagon-like peptide-1 receptor agonists (GLP-1 RAs) in patients with type 2 diabetes (T2D) with and without renal impairment and examines the effects of such use on the clinical outcomes of estimated glomerular filtration rate (eGFR) and glycated hemoglobin (A1c). Data from the Practice Fusion electronic health records database from 1 January 2012 through 30 April 2015 were used. Adults with T2D who received serum creatinine laboratory tests and initiated therapy with a GLP-1 RA (N = 3225) or other glucose-lowering agent (GLA) (N = 37,074) were included in the analysis. The GLP-1 RA cohort was matched to cohorts initiating therapy any other GLA, and multivariable analyses examined the association between GLP-1 RA use and changes in eGFR or A1c at 1 year after therapy initiation. In this study, only 5.7% of patients with an eGFR of Eli Lilly and Company.

Solution structures of the linear leaderless bacteriocins enterocin 7A and 7B resemble carnocyclin A, a circular antimicrobial peptide.

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Lohans, Christopher T; Towle, Kaitlyn M; Miskolzie, Mark; McKay, Ryan T; van Belkum, Marco J; McMullen, Lynn M; Vederas, John C

2013-06-11

Leaderless bacteriocins are a class of ribosomally synthesized antimicrobial peptides that are produced by certain Gram-positive bacteria without an N-terminal leader section. These bacteriocins are of great interest due to their potent inhibition of many Gram-positive organisms, including food-borne pathogens such as Listeria and Clostridium spp. We now report the NMR solution structures of enterocins 7A and 7B, leaderless bacteriocins recently isolated from Enterococcus faecalis 710C. These are the first three-dimensional structures to be reported for bacteriocins of this class. Unlike most other linear Gram-positive bacteriocins, enterocins 7A and 7B are highly structured in aqueous conditions. Both peptides are primarily α-helical, adopting a similar overall fold. The structures can be divided into three separate α-helical regions: the N- and C-termini are both α-helical, separated by a central kinked α-helix. The overall structures bear an unexpected resemblance to carnocyclin A, a 60-residue peptide that is cyclized via an amide bond between the C- and N-termini and has a saposin fold. Because of synergism observed for other two-peptide leaderless bacteriocins, it was of interest to probe possible binding interactions between enterocins 7A and 7B. However, despite synergistic activity observed between these peptides, no significant binding interaction was observed based on NMR and isothermal calorimetry.

Cardiovascular safety and benefits of GLP-1 receptor agonists

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Dalsgaard, Niels B; Brønden, Andreas; Lauritsen, Tina Vilsbøll

2017-01-01

INTRODUCTION: Glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1RAs) constitute a class of drugs for the treatment of type 2 diabetes, and currently, six different GLP-1RAs are approved. Besides improving glycemic control, the GLP-1RAs have other beneficial effects such as weight loss...... and a low risk of hypoglycemia. Treatment with the GLP-1RA lixisenatide has been shown to be safe in patients with type 2 diabetes and recent acute coronary syndrome. Furthermore, liraglutide and semaglutide have been shown to reduce cardiovascular (CV) disease (CVD) risk in type 2 diabetes patients...

Activation of Relaxin Family Receptor 1 from different mammalian species by relaxin peptide and small molecule agonist ML290

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Zaohua eHuang

2015-08-01

Full Text Available Relaxin peptide (RLN, which signals through the relaxin family peptide 1 (RXFP1 GPCR receptor, has shown therapeutic effects in an acute heart failure clinical trial. We have identified a small molecule agonist of human RXFP1, ML290; however, it does not activate the mouse receptor. To find a suitable animal model for ML290 testing and to gain mechanistic insights into the interaction of various ligands with RXFP1, we have cloned rhesus macaque, pig, rabbit, and guinea pig RXFP1s and analyzed their activation by RLN and ML290. HEK293T cells expressing macaque or pig RXFP1 responded to relaxin and ML290 treatment as measured by an increase of cAMP production. Guinea pig RXFP1 responded to relaxin but had very low response to ML290 treatment only at highest concentrations used. The rabbit RXFP1 amino acid sequence was the most divergent, with a number of unique substitutions within the ectodomain and the 7-transmembrane domain (7TM. Two splice variants of rabbit RXFP1 derived through alternative splicing of the forth exon were identified. In contrast to the other species, rabbit RXFP1s were activated by ML290, but not with human, pig, mouse, or rabbit relaxins. Using FLAG-tagged constructs, we have shown that both rabbit RXFP1 variants are expressed on the cell surface. No binding of human Eu-labeled relaxin to rabbit RXFP1 was detected, suggesting that in this species RXFP1 might be non-functional. We used chimeric rabbit-human and guinea pig-human constructs to identify regions important for RLN or ML290 receptor activation. Chimeras with the human ectodomain and rabbit 7TM domain were activated by RLN, whereas substitution of part of the guinea pig 7TM domain with the human sequence only partially restored ML290 activation, confirming the allosteric mode of action for the two ligands. Our data demonstrate that macaque and pig models can be used for ML290 testing.

Model of the complex of Parathyroid hormone-2 receptor and Tuberoinfundibular peptide of 39 residues

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Persson Bengt

2010-10-01

Full Text Available Abstract Background We aim to propose interactions between the parathyroid hormone-2 receptor (PTH2R and its ligand the tuberoinfundibular peptide of 39 residues (TIP39 by constructing a homology model of their complex. The two related peptides parathyroid hormone (PTH and parathyroid hormone related protein (PTHrP are compared with the complex to examine their interactions. Findings In the model, the hydrophobic N-terminus of TIP39 is buried in a hydrophobic part of the central cavity between helices 3 and 7. Comparison of the peptide sequences indicates that the main discriminator between the agonistic peptides TIP39 and PTH and the inactive PTHrP is a tryptophan-phenylalanine replacement. The model indicates that the smaller phenylalanine in PTHrP does not completely occupy the binding site of the larger tryptophan residue in the other peptides. As only TIP39 causes internalisation of the receptor and the primary difference being an aspartic acid in position 7 of TIP39 that interacts with histidine 396 in the receptor, versus isoleucine/histidine residues in the related hormones, this might be a trigger interaction for the events that cause internalisation. Conclusions A model is constructed for the complex and a trigger interaction for full agonistic activation between aspartic acid 7 of TIP39 and histidine 396 in the receptor is proposed.

A novel dual GLP-1 and GIP incretin receptor agonist is neuroprotective in a mouse model of Parkinson's disease by reducing chronic inflammation in the brain.

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Cao, Lijun; Li, Dongfang; Feng, Peng; Li, Lin; Xue, Guo-Fang; Li, Guanglai; Hölscher, Christian

2016-04-13

The incretins glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are growth factors. GLP-1 mimetics are on the market as treatments for type 2 diabetes. Both GLP-1 and GIP mimetics have shown neuroprotective properties in previous studies. In addition, the GLP-1 mimetic exendin-4 has shown protective effects in a clinical trial in Parkinson's disease (PD) patients. Novel GLP-1/GIP dual-agonist peptides have been developed to treat diabetes. Here, we report the neuroprotective effects of a novel dual agonist (DA-JC1) in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. MPTP was injected once daily (20 mg/kg intraperitoneally) for 7 days and the dual agonist was coinjected once daily (50 nmol/kg intraperitoneally). We found that the drug reduced most of the MPTP-induced motor impairments in the rotarod, open-field locomotion, and muscle strength test. The number of tyrosine hydroxylase-positive neurons in the substantia nigra and striatum was reduced by MPTP and increased by DA-JC1. Synapse numbers (synaptophysin expression) were reduced in the substantia nigra and the striatum by MPTP and DA-JC1 reversed this effect. The activation of a chronic inflammation response by MPTP was considerably reduced by the dual agonist (DA) (astroglia and microglia activation). Therefore, dual agonists show promise as a novel treatment of PD.

Antibodies against the melanocortin-4 receptor act as inverse agonists in vitro and in vivo.

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Peter, Jean-Christophe; Nicholson, Janet R; Heydet, Déborah; Lecourt, Anne-Catherine; Hoebeke, Johan; Hofbauer, Karl G

2007-06-01

Functionally active antibodies (Abs) against central G-protein-coupled receptors have not yet been reported. We selected the hypothalamic melanocortin-4 receptor (MC4-R) as a target because of its crucial role in the regulation of energy homeostasis. A 15 amino acid sequence of the N-terminal (NT) domain was used as an antigen. This peptide showed functional activity in surface plasmon resonance experiments and in studies on HEK-293 cells overexpressing the human MC4-R (hMC4-R). Rats immunized against the NT peptide produced specific antibodies, which were purified and characterized in vitro. In HEK-293 cells, rat anti-NT Abs showed specific immunofluorescence labeling of hMC4-R. They reduced the production of cAMP under basal conditions and after stimulation with a synthetic MC4-R agonist. Rats immunized against the NT peptide developed a phenotype consistent with MC4-R blockade, that is, increased food intake and body weight, increased liver and fat pad weight, and elevated plasma triglycerides. In a separate experiment in rats, an increase in food intake could be produced after injection of purified Abs into the third ventricle. Similar results were obtained in rats injected with anti-NT Abs raised in rabbits. Our data show for the first time that active immunization of rats against the NT sequence of the MC4-R results in specific Abs, which appear to stimulate food intake by acting as inverse agonists in the hypothalamus.

Oligomerization of a Glucagon-like Peptide 1 Analog: Bridging Experiment and Simulations

DEFF Research Database (Denmark)

Frederiksen, Tine Maja; Sønderby, Pernille; Ryberg, Line A.

2015-01-01

The glucagon-like peptide 1 (GLP-1) analog, liraglutide, is a GLP-1 agonist and is used in the treatment of type-2 diabetes mellitus and obesity. From a pharmaceutical perspective, it is important to know the oligomerization state of liraglutide with respect to stability. Compared to GLP-1...

Glucagon-Like Peptide-1 (GLP-1) Receptor Agonists in the Treatment of Obese Women with Polycystic Ovary Syndrome.

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Tzotzas, Themistoklis; Karras, Spyridon N; Katsiki, Niki

2017-01-01

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in females and is often associated with a number of cardiometabolic disorders such as central obesity, dyslipidaemia, hypertension, insulin resistance, hyperinsulinaemia, glucose intolerance and type 2 diabetes mellitus (T2DM). Glucagon-like peptide-1 (GLP-1), a gut hormone secreted after a meal, enhances glucosestimulated insulin secretion and additionally suppresses appetite and gastric motility. Most studies found impaired GLP-1 kinetics in obese individuals, whereas small studies in PCOS reported reduced, normal or even elevated GLP-1 levels. Apart from their efficacy in patients with T2DM, some GLP-1 receptor agonists (GLP-1 RAs) have been successfully tested in terms of both efficiency and safety in obese individuals without diabetes and liraglutide 3 mg once daily has been approved as an antiobesity drug in the USA and the European Union. Recently, some small trials of short duration using GLP-1 RAs as monotherapy or combined with metformin in obese PCOS women showed positive results regarding weight reduction and a decrease in testosterone levels but without significant effects on insulin levels, insulin sensitivity and menstrual patterns. Longer term studies with more patients and higher doses of liraglutide (as this drug is already approved for obese individuals) are required to determine the precise indications of GLP-1 RAs in PCOS and to evaluate safety issues. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

MRM screening/biomarker discovery with linear ion trap MS: a library of human cancer-specific peptides

International Nuclear Information System (INIS)

Yang, Xu; Lazar, Iulia M

2009-01-01

The discovery of novel protein biomarkers is essential in the clinical setting to enable early disease diagnosis and increase survivability rates. To facilitate differential expression analysis and biomarker discovery, a variety of tandem mass spectrometry (MS/MS)-based protein profiling techniques have been developed. For achieving sensitive detection and accurate quantitation, targeted MS screening approaches, such as multiple reaction monitoring (MRM), have been implemented. MCF-7 breast cancer protein cellular extracts were analyzed by 2D-strong cation exchange (SCX)/reversed phase liquid chromatography (RPLC) separations interfaced to linear ion trap MS detection. MS data were interpreted with the Sequest-based Bioworks software (Thermo Electron). In-house developed Perl-scripts were used to calculate the spectral counts and the representative fragment ions for each peptide. In this work, we report on the generation of a library of 9,677 peptides (p < 0.001), representing ~1,572 proteins from human breast cancer cells, that can be used for MRM/MS-based biomarker screening studies. For each protein, the library provides the number and sequence of detectable peptides, the charge state, the spectral count, the molecular weight, the parameters that characterize the quality of the tandem mass spectrum (p-value, DeltaM, Xcorr, DeltaCn, Sp, no. of matching a, b, y ions in the spectrum), the retention time, and the top 10 most intense product ions that correspond to a given peptide. Only proteins identified by at least two spectral counts are listed. The experimental distribution of protein frequencies, as a function of molecular weight, closely matched the theoretical distribution of proteins in the human proteome, as provided in the SwissProt database. The amino acid sequence coverage of the identified proteins ranged from 0.04% to 98.3%. The highest-abundance proteins in the cellular extract had a molecular weight (MW)<50,000. Preliminary experiments have

Quantitative Structure-Activity Relationships and Docking Studies of Calcitonin Gene-Related Peptide Antagonists

DEFF Research Database (Denmark)

Jenssen, Håvard; Mehrabian, Mohadeseh; Kyani, Anahita

2012-01-01

Defining the role of calcitonin gene-related peptide in migraine pathogenesis could lead to the application of calcitonin gene-related peptide antagonists as novel migraine therapeutics. In this work, quantitative structure-activity relationship modeling of biological activities of a large range...... of calcitonin gene-related peptide antagonists was performed using a panel of physicochemical descriptors. The computational studies evaluated different variable selection techniques and demonstrated shuffling stepwise multiple linear regression to be superior over genetic algorithm-multiple linear regression....... The linear quantitative structure-activity relationship model revealed better statistical parameters of cross-validation in comparison with the non-linear support vector regression technique. Implementing only five peptide descriptors into this linear quantitative structure-activity relationship model...

Multiple Factors Related to the Secretion of Glucagon-Like Peptide-1

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XingChun Wang

2015-01-01

Full Text Available The glucagon-like peptide-1 is secreted by intestinal L cells in response to nutrient ingestion. It regulates the secretion and sensitivity of insulin while suppressing glucagon secretion and decreasing postprandial glucose levels. It also improves beta-cell proliferation and prevents beta-cell apoptosis induced by cytotoxic agents. Additionally, glucagon-like peptide-1 delays gastric emptying and suppresses appetite. The impaired secretion of glucagon-like peptide-1 has negative influence on diabetes, hyperlipidemia, and insulin resistance related diseases. Thus, glucagon-like peptide-1-based therapies (glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase-4 inhibitors are now well accepted in the management of type 2 diabetes. The levels of glucagon-like peptide-1 are influenced by multiple factors including a variety of nutrients. The component of a meal acts as potent stimulants of glucagon-like peptide-1 secretion. The levels of its secretion change with the intake of different nutrients. Some drugs also have influence on GLP-1 secretion. Bariatric surgery may improve metabolism through the action on GLP-1 levels. In recent years, there has been a great interest in developing effective methods to regulate glucagon-like peptide-1 secretion. This review summarizes the literature on glucagon-like peptide-1 and related factors affecting its levels.

Characterisation of the Novel Mixed Mu-NOP Peptide Ligand Dermorphin-N/OFQ (DeNo.

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Mark F Bird

Full Text Available Opioid receptors are currently classified as Mu (μ, Delta (δ, Kappa (κ plus the opioid related nociceptin/orphanin FQ (N/OFQ peptide receptor (NOP. Despite compelling evidence for interactions and benefits of targeting more than one receptor type in producing analgesia, clinical ligands are Mu agonists. In this study we have designed a Mu-NOP agonist named DeNo. The Mu agonist component is provided by dermorphin, a peptide isolated from the skin of Phyllomedusa frogs and the NOP component by the endogenous agonist N/OFQ.We have assessed receptor binding profile of DeNo and compared with dermorphin and N/OFQ. In a series of functional screens we have assessed the ability to (i increase Ca2+ in cells coexpressing recombinant receptors and a the chimeric protein Gαqi5, (ii stimulate the binding of GTPγ[35S], (iii inhibit cAMP formation, (iv activate MAPKinase, (v stimulate receptor-G protein and arrestin interaction using BRET, (vi electrically stimulated guinea pig ileum (gpI assay and (vii ability to produce analgesia via the intrathecal route in rats.DeNo bound to Mu (pKi; 9.55 and NOP (pKi; 10.22 and with reasonable selectivity. This translated to increased Ca2+ in Gαqi5 expressing cells (pEC50 Mu 7.17; NOP 9.69, increased binding of GTPγ[35S] (pEC50 Mu 7.70; NOP 9.50 and receptor-G protein interaction in BRET (pEC50 Mu 8.01; NOP 9.02. cAMP formation was inhibited and arrestin was activated (pEC50 Mu 6.36; NOP 8.19. For MAPK DeNo activated p38 and ERK1/2 at Mu but only ERK1/2 at NOP. In the gpI DeNO inhibited electrically-evoked contractions (pEC50 8.63 that was sensitive to both Mu and NOP antagonists. DeNo was antinociceptive in rats.Collectively these data validate the strategy used to create a novel bivalent Mu-NOP peptide agonist by combining dermorphin (Mu and N/OFQ (NOP. This molecule behaves essentially as the parent compounds in vitro. In the antonocicoeptive assays employed in this study DeNo displays only weak antinociceptive

Frog secretions and hunting magic in the upper Amazon: identification of a peptide that interacts with an adenosine receptor.

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Daly, J W; Caceres, J; Moni, R W; Gusovsky, F; Moos, M; Seamon, K B; Milton, K; Myers, C W

1992-11-15

A frog used for "hunting magic" by several groups of Panoan-speaking Indians in the borderline between Brazil and Peru is identified as Phyllomedusa bicolor. This frog's skin secretion, which the Indians introduce into the body through fresh burns, is rich in peptides. These include vasoactive peptides, opioid peptides, and a peptide that we have named adenoregulin, with the sequence GLWSKIKEVGKEAAKAAAKAAGKAALGAVSEAV as determined from mass spectrometry and Edman degradation. The natural peptide may contain a D amino acid residue, since it is not identical in chromatographic properties to the synthetic peptide. Adenoregulin enhances binding of agonists to A1 adenosine receptors; it is accompanied in the skin secretion by peptides that inhibit binding. The vasoactive peptide sauvagine, the opioid peptides, and adenoregulin and related peptides affect behavior in mice and presumably contribute to the behavioral sequelae observed in humans.

Acetone-Linked Peptides: A Convergent Approach for Peptide Macrocyclization and Labeling.

Science.gov (United States)

Assem, Naila; Ferreira, David J; Wolan, Dennis W; Dawson, Philip E

2015-07-20

Macrocyclization is a broadly applied approach for overcoming the intrinsically disordered nature of linear peptides. Herein, it is shown that dichloroacetone (DCA) enhances helical secondary structures when introduced between peptide nucleophiles, such as thiols, to yield an acetone-linked bridge (ACE). Aside from stabilizing helical structures, the ketone moiety embedded in the linker can be modified with diverse molecular tags by oxime ligation. Insights into the structure of the tether were obtained through co-crystallization of a constrained S-peptide in complex with RNAse S. The scope of the acetone-linked peptides was further explored through the generation of N-terminus to side chain macrocycles and a new approach for generating fused macrocycles (bicycles). Together, these studies suggest that acetone linking is generally applicable to peptide macrocycles with a specific utility in the synthesis of stabilized helices that incorporate functional tags. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Peptidomic Identification of Cysteine-Rich Peptides from Plants.

Science.gov (United States)

Hemu, Xinya; Serra, Aida; Darwis, Dina A; Cornvik, Tobias; Sze, Siu Kwan; Tam, James P

2018-01-01

Plant cysteine-rich peptides (CRPs) constitute a majority of plant-derived peptides with high molecular diversity. This protocol describes a rapid and efficient peptidomic approach to identify a whole spectrum of CRPs in a plant extract and decipher their molecular diversity and bioprocessing mechanism. Cyclotides from C. ternatea are used as the model CRPs to demonstrate our methodology. Cyclotides exist naturally in both cyclic and linear forms, although the linear forms (acyclotide) are generally present at much lower concentrations. Both cyclotides and acyclotides require linearization of their backbone prior to fragmentation and sequencing. A novel and practical three-step chemoenzymatic treatment was developed to linearize and distinguish both forms: (1) N-terminal acetylation that pre-labels the acyclotides; (2) conversion of Cys into pseudo-Lys through aziridine-mediated S-alkylation to reduce disulfide bonds and to increase the net charge of peptides; and (3) opening of cyclic backbones by the novel asparaginyl endopeptidase butelase 2 that cleaves at the native bioprocessing site. The treated peptides are subsequently analyzed by liquid chromatography coupled to mass spectrometry using electron transfer dissociation fragmentation and sequences are identified by matching the MS/MS spectra directly with the transcriptomic database.

Improved glucose control and reduced body weight in rodents with dual mechanism of action peptide hybrids.

Directory of Open Access Journals (Sweden)

James L Trevaskis

Full Text Available Combination therapy is being increasingly used as a treatment paradigm for metabolic diseases such as diabetes and obesity. In the peptide therapeutics realm, recent work has highlighted the therapeutic potential of chimeric peptides that act on two distinct receptors, thereby harnessing parallel complementary mechanisms to induce additive or synergistic benefit compared to monotherapy. Here, we extend this hypothesis by linking a known anti-diabetic peptide with an anti-obesity peptide into a novel peptide hybrid, which we termed a phybrid. We report on the synthesis and biological activity of two such phybrids (AC164204 and AC164209, comprised of a glucagon-like peptide-1 receptor (GLP1-R agonist, and exenatide analog, AC3082, covalently linked to a second generation amylin analog, davalintide. Both molecules acted as full agonists at their cognate receptors in vitro, albeit with reduced potency at the calcitonin receptor indicating slightly perturbed amylin agonism. In obese diabetic Lep(ob/Lep (ob mice sustained infusion of AC164204 and AC164209 reduced glucose and glycated haemoglobin (HbA1c equivalently but induced greater weight loss relative to exenatide administration alone. Weight loss was similar to that induced by combined administration of exenatide and davalintide. In diet-induced obese rats, both phybrids dose-dependently reduced food intake and body weight to a greater extent than exenatide or davalintide alone, and equal to co-infusion of exenatide and davalintide. Phybrid-mediated and exenatide + davalintide-mediated weight loss was associated with reduced adiposity and preservation of lean mass. These data are the first to provide in vivo proof-of-concept for multi-pathway targeting in metabolic disease via a peptide hybrid, demonstrating that this approach is as effective as co-administration of individual peptides.

Actions of vasoactive intestinal peptide and secretin on chief cells prepared from guinea pig stomach

International Nuclear Information System (INIS)

Sutliff, V.E.; Raufman, J.P.; Jensen, R.T.; Gardner, J.D.

1986-01-01

Vasoactive intestinal peptide and secretin increased cellular cAMP and pepsinogen secretion in dispersed chief cells from guinea pig gastric mucosa. With each peptide there was a close correlation between the dose-response curve for changes in cellular cAMP and that for changes in pepsinogen secretion. Vasoactive intestinal peptide- (10-28) and secretin- (5-27) had no agonist activity and antagonized the actions of vasoactive intestinal peptide and secretin on cellular cAMP and pepsinogen secretion. Studies of binding of 125 I-vasoactive intestinal peptide and of 125 -secretin indicated that gastric chief cells possess four classes of binding sites for vasoactive intestinal peptide and secretin and that occupation of two of these classes of binding sites correlates with the abilities of vasoactive intestinal peptide and secretin to increase cellular cAMP and pepsinogen secretion. What function, in any, is mediated by occupation by the other two classes of binding sites remains to be determined

Characterization of cyclic peptides containing disulfide bonds

OpenAIRE

Johnson, Mindy; Liu, Mingtao; Struble, Elaine; Hettiarachchi, Kanthi

2015-01-01

Unlike linear peptides, analysis of cyclic peptides containing disulfide bonds is not straightforward and demands indirect methods to achieve a rigorous proof of structure. Three peptides that belong to this category, p-Cl-Phe-DPDPE, DPDPE, and CTOP, were analyzed and the results are presented in this paper. The great potential of two dimensional NMR and ESI tandem mass spectrometry was harnessed during the course of peptide characterizations. A new RP-HPLC method for the analysis of trifluor...

Role of sulfate ester in influencing biological activity of cholecystokinin-related peptides

International Nuclear Information System (INIS)

Vinayek, R.; Jensen, R.T.; Gardner, J.D.

1987-01-01

In dispersed acini from guinea pig, mouse, or rat pancreas cholecystokinin-(27-33) is a full agonist, and removing the sulfate ester from the tyrosine residue in position 27 caused a 100- to 300-fold decrease in potency with no change in efficacy. In dispersed acini from mouse or rat pancreas, cholecystokinin-(27-32)-NH 2 is a partial agonist, and removing the sulfate ester from the tyrosine in position 27 abolished the efficacy. The desulfated peptide was able, however, to interact with [ 125 I] CCK receptors with a potency that was threefold less than that of cholecystokinin-(27-32)-NH 2 and therefore functioned as a cholecystokinin receptor antagonist. In dispersed acini from guinea pig pancreas cholecystokinin-(27-32)-NH 2 is a cholecystokinin receptor antagonist. Removing the sulfate ester from the tyrosine residue in position 27 of cholecystokinin-(27-32)-NH 2 caused a fourfold decrease in potency but did not abolish the ability of the peptide to interact with cholecystokinin receptors; therefore, desulfated cholecystokinin-(27-32)-NH 2 functioned as a cholecystokinin receptor antagonist

High constitutive signaling of the ghrelin receptor--identification of a potent inverse agonist

DEFF Research Database (Denmark)

Holst, Birgitte; Cygankiewicz, Adam; Jensen, Tine Halkjaer

2003-01-01

Ghrelin is a GH-releasing peptide that also has an important role as an orexigenic hormone-stimulating food intake. By measuring inositol phosphate turnover or by using a reporter assay for transcriptional activity controlled by cAMP-responsive elements, the ghrelin receptor showed strong, ligand......-independent signaling in transfected COS-7 or human embryonic kidney 293 cells. Ghrelin and a number of the known nonpeptide GH secretagogues acted as agonists stimulating inositol phosphate turnover further. In contrast, the low potency ghrelin antagonist, [D-Arg1,D-Phe5,D-Trp7,9,Leu11]-substance P was surprisingly...... found to be a high potency (EC50 = 5.2 nm) full inverse agonist as it decreased the constitutive signaling of the ghrelin receptor down to that observed in untransfected cells. The homologous motilin receptor functioned as a negative control as it did not display any sign of constitutive activity...

Fine-mapping of immunodominant linear B-cell epitopes of the Staphylococcus aureus SEB antigen using short overlapping peptides.

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Zhuo Zhao

Full Text Available Staphylococcal enterotoxin B (SEB is one of the most potent Staphylococcus aureus exotoxins (SEs. Due to its conserved sequence and stable structure, SEB might be a good candidate antigen for MRSA vaccines. Although cellular immune responses to SEB are well-characterized, much less is known regarding SEB-specific humoral immune responses, particularly regarding detailed epitope mapping. In this study, we utilized a recombinant nontoxic mutant of SEB (rSEB and an AlPO4 adjuvant to immunize BALB/c mice and confirmed that rSEB can induce a high antibody level and effective immune protection against MRSA infection. Next, the antisera of immunized mice were collected, and linear B cell epitopes within SEB were finely mapped using a series of overlapping synthetic peptides. Three immunodominant B cell epitopes of SEB were screened by ELISA, including a novel epitope, SEB205-222, and two known epitopes, SEB97-114 and SEB247-261. Using truncated peptides, an ELISA was performed with peptide-KLH antisera, and the core sequence of the three immunodominant B cell epitopes were verified as SEB97-112, SEB207-222, and SEB247-257. In vitro, all of the immunodominant epitope-specific antisera (anti-SEB97-112, anti-SEB207-222 and anti-SEB247-257 were observed to inhibit SEB-induced T cell mitogenesis and cytokine production from splenic lymphocytes of BALB/c mice. The homology analysis indicated that SEB97-112 and SEB207-222 were well-conserved among different Staphylococcus aureus strains. The 3D crystal structure of SEB indicated that SEB97-112 was in the loop region inside SEB, whereas SEB207-222 and SEB247-257 were in the β-slice region outside SEB. In summary, the fine-mapping of linear B-cell epitopes of the SEB antigen in this study will be useful to understand anti-SEB immunity against MRSA infection further and will be helpful to optimize MRSA vaccine designs that are based on the SEB antigen.

Strategies to improve outcome after islet transplantation using the GLP-1 receptor agonist, extendin-4

OpenAIRE

Sharma, Amit

2007-01-01

Transplantation of pancreatic islets into the liver via the portal vein has emerged as a treatment option for patients with type I diabetes mellitus. However, loss of functional beta cell mass during isolation and following implantation is a major obstacle in obtaining good long-term results. Exendin-4, a glucagonlike peptide-1 (GLP-1) receptor agonist, improves glucose homeostasis in patients with diabetes. It also has anti-apoptotic and beta cell proliferative properties t...

D-Arg0-Bradykinin-Arg-Arg, a Latent Vasoactive Bradykinin B2 Receptor Agonist Metabolically Activated by Carboxypeptidases

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Hélène Bachelard

2018-03-01

Full Text Available We previously reported hypotensive and vasodilator effects from C-terminally extended bradykinin (BK sequences that behave as B2 receptor (B2R agonists activated by vascular or plasma peptidases. D-Arg0-BK-Arg-Arg (r-BK-RR is a novel prodrug peptide hypothetically activated by two catalytic cycles of Arg-carboxypeptidases (CPs to release the direct agonist D-Arg0-BK. N-terminally extending the BK sequence with D-Arg0 in the latter peptide was meant to block the second kinin inactivation pathway in importance, aminopeptidase P. The affinity of r-BK and r-BK-RR for recombinant B2R was assessed using a [3H]BK binding displacement assay. Their pharmacology was evaluated in human isolated umbilical vein, a contractile bioassay for the B2R, in a morphological assay involving the endocytosis of B2R-green fusion protein (GFP and in anesthetized rats instrumented to record hemodynamic responses to bolus intravenous injection of both peptides. r-BK exhibited an affinity equal to that of BK for the rat B2R, while r-BK-RR was 61-fold less potent. In the vein and the B2R-GFP internalization assay, r-BK was a direct agonist unaffected by the blockade of angiotensin converting enzyme (ACE with enalaprilat, or Arg-CPs with Plummer’s inhibitor. However, the in vitro effects of r-BK-RR were reduced by these inhibitors, more so by enalaprilat. In anesthetized rats, r-BK and r-BK-RR were equipotent hypotensive agents and their effects were inhibited by icatibant (a B2R antagonist. The hypotensive effects of r-BK were potentiated by enalaprilat, but not influenced by the Arg-CPs inhibitor, which is consistent with a minor role of Arg-CPs in the metabolism of r-BK. However, in rats pretreated with both enalaprilat and Plummer’s inhibitor, the hypotensive responses and the duration of the hypotensive episode to r-BK were significantly potentiated. The hypotensive responses to r-BK-RR were not affected by enalaprilat, but were reduced by pre-treatment with the Arg

Identification and in Vivo Evaluation of Liver X Receptor β-Selective Agonists for the Potential Treatment of Alzheimer’s Disease

Energy Technology Data Exchange (ETDEWEB)

Stachel, Shawn J.; Zerbinatti, Celina; Rudd, Michael T.; Cosden, Mali; Suon, Sokreine; Nanda, Kausik K.; Wessner, Keith; DiMuzio, Jillian; Maxwell, Jill; Wu, Zhenhua; Uslaner, Jason M.; Michener, Maria S.; Szczerba, Peter; Brnardic, Edward; Rada, Vanessa; Kim, Yuntae; Meissner, Robert; Wuelfing, Peter; Yuan, Yang; Ballard, Jeanine; Holahan, Marie; Klein, Daniel J.; Lu, Jun; Fradera, Xavier; Parthasarathy, Gopal; Uebele, Victor N.; Chen, Zhongguo; Li, Yingjie; Li, Jian; Cooke, Andrew J.; Bennett, D. Jonathan; Bilodeau, Mark T.; Renger, John (Merck); (WuXi App Tec)

2016-04-14

Herein, we describe the development of a functionally selective liver X receptor β (LXRβ) agonist series optimized for Emax selectivity, solubility, and physical properties to allow efficacy and safety studies in vivo. Compound 9 showed central pharmacodynamic effects in rodent models, evidenced by statistically significant increases in apolipoprotein E (apoE) and ATP-binding cassette transporter levels in the brain, along with a greatly improved peripheral lipid safety profile when compared to those of full dual agonists. These findings were replicated by subchronic dosing studies in non-human primates, where cerebrospinal fluid levels of apoE and amyloid-β peptides were increased concomitantly with an improved peripheral lipid profile relative to that of nonselective compounds. These results suggest that optimization of LXR agonists for Emax selectivity may have the potential to circumvent the adverse lipid-related effects of hepatic LXR activity.

Divergent unprotected peptide macrocyclisation by palladium-mediated cysteine arylation.

Science.gov (United States)

Rojas, Anthony J; Zhang, Chi; Vinogradova, Ekaterina V; Buchwald, Nathan H; Reilly, John; Pentelute, Bradley L; Buchwald, Stephen L

2017-06-01

Macrocyclic peptides are important therapeutic candidates due to their improved physicochemical properties in comparison to their linear counterparts. Here we detail a method for a divergent macrocyclisation of unprotected peptides by crosslinking two cysteine residues with bis-palladium organometallic reagents. These synthetic intermediates are prepared in a single step from commercially available aryl bis-halides. Two bioactive linear peptides with cysteine residues at i , i + 4 and i , i + 7 positions, respectively, were cyclised to introduce a diverse array of aryl and bi-aryl linkers. These two series of macrocyclic peptides displayed similar linker-dependent lipophilicity, phospholipid affinity, and unique volume of distributions. Additionally, one of the bioactive peptides showed target binding affinity that was predominantly affected by the length of the linker. Collectively, this divergent strategy allowed rapid and convenient access to various aryl linkers, enabling the systematic evaluation of the effect of appending unit on the medicinal properties of macrocyclic peptides.

The physiology of glucagon-like peptide 1

DEFF Research Database (Denmark)

Holst, Jens Juul

2007-01-01

Glucagon-like peptide 1 (GLP-1) is a 30-amino acid peptide hormone produced in the intestinal epithelial endocrine L-cells by differential processing of proglucagon, the gene which is expressed in these cells. The current knowledge regarding regulation of proglucagon gene expression in the gut...... and in the brain and mechanisms responsible for the posttranslational processing are reviewed. GLP-1 is released in response to meal intake, and the stimuli and molecular mechanisms involved are discussed. GLP-1 is extremely rapidly metabolized and inactivated by the enzyme dipeptidyl peptidase IV even before...... postprandial glucose excursions. It also inhibits gastrointestinal motility and secretion and thus acts as an enterogastrone and part of the "ileal brake" mechanism. GLP-1 also appears to be a physiological regulator of appetite and food intake. Because of these actions, GLP-1 or GLP-1 receptor agonists...

Treatment of antipsychotic-associated obesity with a GLP-1 receptor agonist--protocol for an investigator-initiated prospective, randomised, placebo-controlled, double-blinded intervention study

DEFF Research Database (Denmark)

Ishøy, Pelle L; Knop, Filip K; Broberg, Brian V

2014-01-01

-associated obesity are limited and insufficient. Glucagon-like peptide-1 (GLP-1) receptor agonists are approved for the treatment of type 2 diabetes, but their bodyweight-lowering effects have also been recognised in patients with non-diabetes. The primary endpoint of this trial is weight loss after 3 months...... of treatment with a GLP-1 receptor agonist (exenatide once weekly) in patients with non-diabetic schizophrenia with antipsychotic-associated obesity. Secondary endpoints include physiological and metabolic measurements, various psychopathological and cognitive measures, and structural and functional brain MRI....

Decapeptides as effective agonists from L-amino acids biologically equivalent to the luteinizing hormone-releasing hormone

International Nuclear Information System (INIS)

Folkers, K.; Bowers, C.Y.; Tang, P.L.; Kubota, M.

1986-01-01

Apparently, no agonist has been found that is comparable in potency to the luteinizing hormone-releasing hormone (LHRH) for release of LH and follicle-stimulating hormone (FSH) without substitutions with unnatural or D forms of natural amino acids. Of 139 known agonist analogs of LHRH, two were active in the range of 65%. The four LHRHs known to occur in nature involve a total of six amino acids (Tyr, His, Leu, Trp, Arg, Gln) in positions 5, 7, and 8. There are 16 possible peptides with these six amino acids in positions 5, 7, and 8, of which 4 are the known LHRHs, and 2 more were synthesized. The authors have synthesized the 10 new peptides and assayed 11 in vivo and in vitro, and they found not only 1 but a total of 5 that have activity equivalent to or greater than that of LHRH for the release of LH and/or FSH under at least one assay condition. These five are as follows: [His 5 ,Trp 7 ,Gln 8 ]LHRH; [His 5 ,Trp 7 ,Leu 8 ]LHRH; [His 5 ,Trp 7 ]LHRH; [Trp 7 ]LHRH; [His 5 ]LHRH. These structures are a basis for the design of antagonists without Arg 8 toward avoiding histamine release. Complete inhibition of LH and FSH release in vivo may be induced by joint use of Arg 8 and Gln 8 or Leu 8 antagonists. These potent agonists, related to LHRH, may be therapeutically useful in disorders of reproduction, the central nervous system, and for the control of hormone-dependent carcinomas. Radioreceptor assays and radioimmunoassays were utilized

Combining GLP-1 receptor agonists with insulin

DEFF Research Database (Denmark)

Holst, Jens Juul; Vilsbøll, T

2013-01-01

Due to the increasing prevalence of type 2 diabetes mellitus (T2DM), the emergent trend towards diagnosis in younger patients and the progressive nature of this disease, many more patients than before now require insulin to maintain glycaemic control. However, there is a degree of inertia among...... physicians and patients regarding the initiation and intensification of insulin therapy, in part due to concerns about the associated weight gain and increased risk of hypoglycaemia. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) increase insulin release and suppress glucagon secretion in a glucose......, compared with insulin, the antihyperglycaemic efficacy of GLP-1RAs is limited. The combination of a GLP-1RA and insulin might thus be highly effective for optimal glucose control, ameliorating the adverse effects typically associated with insulin. Data from clinical studies support the therapeutic...

1,2,3-Triazole Rings as a Disulfide Bond Mimetic in Chimeric AGRP-Melanocortin Peptides: Design, Synthesis, and Functional Characterization.

Science.gov (United States)

Tala, Srinivasa R; Singh, Anamika; Lensing, Cody J; Schnell, Sathya M; Freeman, Katie T; Rocca, James R; Haskell-Luevano, Carrie

2018-05-16

The melanocortin system is involved in the regulation of complex physiological functions, including energy and weight homeostasis, feeding behavior, inflammation, sexual function, pigmentation, and exocrine gland function. The five melanocortin receptors that belong to the superfamily of G protein-coupled receptors (GPCRs) are regulated by endogenously expressed agonists and antagonists. The aim of this study was to explore the potential of replacing the disulfide bridge in chimeric AGRP-melanocortin peptide Tyr-c[Cys-His-d-Phe-Arg-Trp-Asn-Ala-Phe-Cys]-Tyr-NH 2 (1) with 1,2,3-triazole moieties. A series of 1,2,3-triazole-bridged peptidomimetics were designed, synthesized, and pharmacologically evaluated at the mouse melanocortin receptors. The ligands possessed nanomolar to micromolar agonist cAMP signaling potency. A key finding was that the disulfide bond in peptide 1 can be replaced with the monotriazole ring with minimal effect on the functional activity at the melanocortin receptors. The 1,5-disubstituted triazole-bridged peptide 6 showed equipotent functional activity at the mMC3R and modest 5-fold decreased agonist potency at the mMC4R compared to those of 1. Interestingly, the 1,4- and 1,5-disubstituted isomers of the triazole ring resulted in different selectivities at the receptor subtypes, indicating subtle structural features that may be exploited in the generation of selective melanocortin ligands. Introducing cyclic and acyclic bis-triazole moieties into chimeric AGRP template 1 generally decreased agonist activity. These results will be useful for the further design of neuronal chemical probes for the melanocortin receptors as well as in other receptor systems.

Structure, synthesis, and activity of dermaseptin b, a novel vertebrate defensive peptide from frog skin: relationship with adenoregulin.

Science.gov (United States)

Mor, A; Amiche, M; Nicolas, P

1994-05-31

A novel antimicrobial peptide, designated dermaseptin b, was isolated from the skin of the arboreal frog Phyllomedusa bicolor. This 27-residue peptide amide is basic, containing 3 lysine residues that punctuate an alternating hydrophobic and hydrophilic sequence. In helix-inducing solvent, dermaseptin b adopts an amphipathic alpha-helical conformation that most closely resembles class L amphipathic helixes, with all lysine residues on the polar face of the helix. The peptide exhibits growth inhibition activity in vitro against a broad spectrum of pathogenic microorganisms including yeast and bacteria as well as various filamentous fungi that are responsible for severe opportunistic infections accompanying acquired immunodeficiency syndrome and the use of immunosuppressive agents. Maximized pairwise sequence alignment of dermaseptin b and dermaseptin s, a 34-residue antimicrobial peptide previously isolated from Phyllomedusa sauvagii, reveals 81% amino acid identity. No other significant similarity was found between dermaseptin b and any prokaryotic or eukaryotic protein, but similarity was found with adenoregulin (38% amino acid postional identity), a 33-residue peptide that enhances binding of agonists to the A1 adenosine receptor. The synthetic replicates of dermaseptin b and adenoregulin displayed similar but nonidentical spectra of antimicrobial activity, and both peptides were devoid of lytic effect on mammalian cells. Accordingly, the observation that adenoregulin enhances binding of agonists to the adenosine receptor may in fact be a consequence of its ability to alter the structure of biological membranes and to produce signal transduction via interactions with the lipid bilayer, bypassing cell surface receptor interactions.

Epobis is a Nonerythropoietic and Neuroprotective Agonist of the Erythropoietin Receptor with Anti-Inflammatory and Memory Enhancing Effects

DEFF Research Database (Denmark)

Dmytriyeva, Oksana; Pankratova, Stanislava; Korshunova, Irina

2016-01-01

, but systemic administration of Epobis in rats delays the clinical signs of experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis, and the peptide has long-term, but not short-term, effects on working memory, detected as an improved social memory 3 days after administration....... These data reveal Epobis to be a nonerythropoietic and neuroprotective EPO receptor agonist with anti-inflammatory and memory enhancing properties....

Neuritogenic and neuroprotective properties of peptide agonists of the fibroblast growth factor receptor

DEFF Research Database (Denmark)

Li, Shizhong; Bock, Elisabeth Marianne; Berezin, Vladimir

2010-01-01

of protein structure, in silico modeling and biological studies have recently resulted in the identification of FGFR binding peptides derived from various FGFs and NCAM mimicking the effects of these molecules with regard to their neuritogenic and neuroprotective properties. This review focuses on recently...

Cationic antimicrobial peptides inactivate Shiga toxin-encoding bacteriophages

Science.gov (United States)

Del Cogliano, Manuel E.; Hollmann, Axel; Martinez, Melina; Semorile, Liliana; Ghiringhelli, Pablo D.; Maffía, Paulo C.; Bentancor, Leticia V.

2017-12-01

Shiga toxin (Stx) is the principal virulence factor during Shiga toxin-producing Escherichia coli (STEC) infections. We have previously reported the inactivation of bacteriophage encoding Stx after treatment with chitosan, a linear polysaccharide polymer with cationic properties. Cationic antimicrobial peptides (cAMPs) are short linear aminoacidic sequences, with a positive net charge, which display bactericidal or bacteriostatic activity against a wide range of bacterial species. They are promising novel antibiotics since they have shown bactericidal effects against multiresistant bacteria. To evaluate whether cationic properties are responsible for bacteriophage inactivation, we tested seven cationic peptides with proven antimicrobial activity as anti-bacteriophage agents, and one random sequence cationic peptide with no antimicrobial activity as a control. We observed bacteriophage inactivation after incubation with five cAMPs, but no inactivating activity was observed with the random sequence cationic peptide or with the non alpha helical cAMP Omiganan. Finally, to confirm peptide-bacteriophage interaction, zeta potential was analyzed by following changes on bacteriophage surface charges after peptide incubation. According to our results we could propose that: 1) direct interaction of peptides with phage is a necessary step for bacteriophage inactivation, 2) cationic properties are necessary but not sufficient for bacteriophage inactivation, and 3) inactivation by cationic peptides could be sequence (or structure) specific. Overall our data suggest that these peptides could be considered a new family of molecules potentially useful to decrease bacteriophage replication and Stx expression.

Cationic Antimicrobial Peptides Inactivate Shiga Toxin-Encoding Bacteriophages

Directory of Open Access Journals (Sweden)

Manuel E. Del Cogliano

2017-12-01

Full Text Available Shiga toxin (Stx is the principal virulence factor during Shiga toxin-producing Escherichia coli (STEC infections. We have previously reported the inactivation of bacteriophage encoding Stx after treatment with chitosan, a linear polysaccharide polymer with cationic properties. Cationic antimicrobial peptides (cAMPs are short linear aminoacidic sequences, with a positive net charge, which display bactericidal or bacteriostatic activity against a wide range of bacterial species. They are promising novel antibiotics since they have shown bactericidal effects against multiresistant bacteria. To evaluate whether cationic properties are responsible for bacteriophage inactivation, we tested seven cationic peptides with proven antimicrobial activity as anti-bacteriophage agents, and one random sequence cationic peptide with no antimicrobial activity as a control. We observed bacteriophage inactivation after incubation with five cAMPs, but no inactivating activity was observed with the random sequence cationic peptide or with the non-alpha helical cAMP Omiganan. Finally, to confirm peptide-bacteriophage interaction, zeta potential was analyzed by following changes on bacteriophage surface charges after peptide incubation. According to our results we could propose that: (1 direct interaction of peptides with phage is a necessary step for bacteriophage inactivation, (2 cationic properties are necessary but not sufficient for bacteriophage inactivation, and (3 inactivation by cationic peptides could be sequence (or structure specific. Overall our data suggest that these peptides could be considered a new family of molecules potentially useful to decrease bacteriophage replication and Stx expression.

Treatment Strategy for Type 2 Diabetes with Obesity: Focus on Glucagon-like Peptide-1 Receptor Agonists.

Science.gov (United States)

Ji, Qiuhe

2017-06-01

The progressive nature of type 2 diabetes mellitus (T2DM) calls for step-wise intensification of therapy for maintaining normal glycemic levels and lowering cardiovascular (CV) risk. Because obesity is a prominent risk factor and comorbidity of T2DM, it further elevates the CV risk in T2DM. Therefore, it is vital to manage weight, obesity, and glycemic parameters for effective T2DM management. Few oral antidiabetic drugs (sulfonylureas and thiazolidinediones) and insulin are not suitable for obese patients with T2DM because these drugs cause weight gain. The present review discusses the place of glucagon-like peptide-1 receptor agonists (GLP-1RAs) in the treatment of obese patients with T2DM and the significance of these drugs in the prevention of future CV risk in patients with T2DM. A literature search of PubMed and EMBASE was conducted by using the search terms T2DM, GLP-1RAs, obesity, and cardiovascular complication. Randomized controlled trials measuring the effect of GLP-1RAs versus that of placebo on CV outcomes were included in the review. GLP-1RAs have emerged as a therapeutic alternative; these drugs exert their actions by providing glycemic control, improving insulin resistance and ö̇-cell function, and reducing weight. The risk of hypoglycemia with GLP-1RAs is minimal; however, GLP-1RAs are associated with gastrointestinal adverse events and raise concerns regarding pancreatitis. Combining GLP-1RAs with insulin analogues results in higher efficacy, a lowered insulin dose, and reduced insulin-related hypoglycemia and weight gain. Longer acting GLP-1RAs are also associated with improvement in medication adherence. Improvement in CV risk factors such as blood pressure and lipid profile further increases their usability for improving CV outcomes. Overall, the properties of GLP-1RAs make them suitable for combination with oral antidiabetic drugs in the early stages of T2DM and with insulins in the later stages for optimizing comprehensive management of the

Negative cooperativity in binding of muscarinic receptor agonists and GDP as a measure of agonist efficacy.

Science.gov (United States)

Jakubík, J; Janíčková, H; El-Fakahany, E E; Doležal, V

2011-03-01

Conventional determination of agonist efficacy at G-protein coupled receptors is measured by stimulation of guanosine-5'-γ-thiotriphosphate (GTPγS) binding. We analysed the role of guanosine diphosphate (GDP) in the process of activation of the M₂ muscarinic acetylcholine receptor and provide evidence that negative cooperativity between agonist and GDP binding is an alternative measure of agonist efficacy. Filtration and scintillation proximity assays measured equilibrium binding as well as binding kinetics of [³⁵S]GTPγS and [³H]GDP to a mixture of G-proteins as well as individual classes of G-proteins upon binding of structurally different agonists to the M₂ muscarinic acetylcholine receptor. Agonists displayed biphasic competition curves with the antagonist [³H]-N-methylscopolamine. GTPγS (1 µM) changed the competition curves to monophasic with low affinity and 50 µM GDP produced a similar effect. Depletion of membrane-bound GDP increased the proportion of agonist high-affinity sites. Carbachol accelerated the dissociation of [³H]GDP from membranes. The inverse agonist N-methylscopolamine slowed GDP dissociation and GTPγS binding without changing affinity for GDP. Carbachol affected both GDP association with and dissociation from G(i/o) G-proteins but only its dissociation from G(s/olf) G-proteins. These findings suggest the existence of a low-affinity agonist-receptor conformation complexed with GDP-liganded G-protein. Also the negative cooperativity between GDP and agonist binding at the receptor/G-protein complex determines agonist efficacy. GDP binding reveals differences in action of agonists versus inverse agonists as well as differences in activation of G(i/o) versus G(s/olf) G-proteins that are not identified by conventional GTPγS binding. © 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society.

Peptide mimic for influenza vaccination using nonnatural combinatorial chemistry

Science.gov (United States)

Miles, John J.; Tan, Mai Ping; Dolton, Garry; Galloway, Sarah A.E.; Laugel, Bruno; Makinde, Julia; Matthews, Katherine K.; Watkins, Thomas S.; Wong, Yide; Clark, Richard J.; Pentier, Johanne M.; Attaf, Meriem; Lissina, Anya; Ager, Ann; Gallimore, Awen; Gras, Stephanie; Rossjohn, Jamie; Burrows, Scott R.; Cole, David K.; Price, David A.

2018-01-01

Polypeptide vaccines effectively activate human T cells but suffer from poor biological stability, which confines both transport logistics and in vivo therapeutic activity. Synthetic biology has the potential to address these limitations through the generation of highly stable antigenic “mimics” using subunits that do not exist in the natural world. We developed a platform based on D–amino acid combinatorial chemistry and used this platform to reverse engineer a fully artificial CD8+ T cell agonist that mirrored the immunogenicity profile of a native epitope blueprint from influenza virus. This nonnatural peptide was highly stable in human serum and gastric acid, reflecting an intrinsic resistance to physical and enzymatic degradation. In vitro, the synthetic agonist stimulated and expanded an archetypal repertoire of polyfunctional human influenza virus–specific CD8+ T cells. In vivo, specific responses were elicited in naive humanized mice by subcutaneous vaccination, conferring protection from subsequent lethal influenza challenge. Moreover, the synthetic agonist was immunogenic after oral administration. This proof-of-concept study highlights the power of synthetic biology to expand the horizons of vaccine design and therapeutic delivery. PMID:29528337

Two new bradykinin-related peptides from the venom of the social wasp Protopolybia exigua (Saussure).

Science.gov (United States)

Mendes, Maria Anita; Palma, Mario Sergio

2006-11-01

Two bradykinin-related peptides (Protopolybiakinin-I and Protopolybiakinin-II) were isolated from the venom of the social wasp Protopolybia exigua by RP-HPLC, and sequenced by Edman degradation method. Peptide sequences of Protopolybiakinin-I and Protopolybiakinin-II were DKNKKPIRVGGRRPPGFTR-OH and DKNKKPIWMAGFPGFTPIR-OH, respectively. Synthetic peptides with identical sequences to the bradykinin-related peptides and their biological functions were characterized. Protopolybiakinin-I caused less potent constriction of the isolated rat ileum muscles than bradykinin (BK). In addition, it caused degranulation of mast cells which was seven times more potent than BK. This peptide causes algesic effects due to the direct activation of B(2)-receptors. Protopolybiakinin-II is not an agonist of rat ileum muscle and had no algesic effects. However, Protopolybiakinin-II was found to be 10 times more potent as a mast cell degranulator than BK. The amino acid sequence of Protopolybiakinin-I is the longest among the known wasp kinins.

Multiple and sequential data acquisition method: an improved method for fragmentation and detection of cross-linked peptides on a hybrid linear trap quadrupole Orbitrap Velos mass spectrometer.

Science.gov (United States)

Rudashevskaya, Elena L; Breitwieser, Florian P; Huber, Marie L; Colinge, Jacques; Müller, André C; Bennett, Keiryn L

2013-02-05

The identification and validation of cross-linked peptides by mass spectrometry remains a daunting challenge for protein-protein cross-linking approaches when investigating protein interactions. This includes the fragmentation of cross-linked peptides in the mass spectrometer per se and following database searching, the matching of the molecular masses of the fragment ions to the correct cross-linked peptides. The hybrid linear trap quadrupole (LTQ) Orbitrap Velos combines the speed of the tandem mass spectrometry (MS/MS) duty circle with high mass accuracy, and these features were utilized in the current study to substantially improve the confidence in the identification of cross-linked peptides. An MS/MS method termed multiple and sequential data acquisition method (MSDAM) was developed. Preliminary optimization of the MS/MS settings was performed with a synthetic peptide (TP1) cross-linked with bis[sulfosuccinimidyl] suberate (BS(3)). On the basis of these results, MSDAM was created and assessed on the BS(3)-cross-linked bovine serum albumin (BSA) homodimer. MSDAM applies a series of multiple sequential fragmentation events with a range of different normalized collision energies (NCE) to the same precursor ion. The combination of a series of NCE enabled a considerable improvement in the quality of the fragmentation spectra for cross-linked peptides, and ultimately aided in the identification of the sequences of the cross-linked peptides. Concurrently, MSDAM provides confirmatory evidence from the formation of reporter ions fragments, which reduces the false positive rate of incorrectly assigned cross-linked peptides.

Incretin-based treatment of type 2 diabetes: glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase-4 inhibitors

DEFF Research Database (Denmark)

Deacon, Carolyn F

2007-01-01

Incretins are gut peptides that potentiate nutrient-stimulated insulin secretion following meal ingestion. Activities of the dominant incretins, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide, include glucose-dependent stimulation of insulin secretion and, in preclin...... and liraglutide) and DPP-4 inhibitors that act to increase concentrations of endogenous intact incretins (e.g. sitagliptin and vildagliptin). Clinical trials of these incretin-based therapies have shown them to be effective in improving glycaemic control in patients with T2DM....

Exendin-4, but not glucagon-like peptide-1, is cleared exclusively by glomerular filtration in anaesthetised pigs

DEFF Research Database (Denmark)

Simonsen, L; Holst, Jens Juul; Deacon, C F

2006-01-01

AIMS/HYPOTHESIS: The insulinotropic hormone, glucagon-like peptide-1 (GLP-1), is rapidly degraded in vivo as a result of the combination of extensive enzymatic degradation and renal extraction. The GLP-1 receptor agonist, exendin-4, has a longer duration of action, and has recently been approved ...

Imaging of urokinase-type plasminogen activator receptor expression using a 64Cu-labeled linear peptide antagonist by microPET

DEFF Research Database (Denmark)

Li, Zi-Bo; Niu, Gang; Wang, Hui

2008-01-01

for positron emission tomography (PET) imaging. A linear, high-affinity uPAR-binding peptide antagonist AE105 was conjugated with 1,4,7,10-tetraazadodecane-N,N',N'',N'''-tetraacetic acid (DOTA) and labeled with (64)Cu for microPET imaging of mice bearing U87MG human glioblastoma (uPAR positive) and MDA-MB-435...... human breast cancer (uPAR negative). RESULTS: Surface plasmon resonance measurements show that AE105 with DOTA conjugated at the alpha-amino group (DOTA-AE105) has high affinity toward uPAR. microPET imaging reveals a rapid and high accumulation of (64)Cu-DOTA-AE105 in uPAR-positive U87MG tumors (10.......8 +/- 1.5%ID/g at 4.5 hours, n = 3) but not in uPAR-negative MDA-MB-435 tumors (1.2 +/- 0.6%ID/g at 4.5 hours, n = 3). Specificity of this peptide-based imaging of uPAR was validated by further control experiments. First, a nonbinding variant of AE105 carrying a single amino acid replacement (Trp...

BIOACTIVE PEPTIDES OF THE COW MILK WHEY PROTEINS (Bos taurus

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A. V. Iukalo

2013-10-01

Full Text Available Data on the biological functions of milk whey proteins, which are implemented at the level of their proteolytic degradation products — bioactive peptides have been reviewed. The main functions of these proteins is to provide the amino acid nutrition of mammals in the early stages of development, as well as the transport of fatty acids, retinol, involved in the synthesis of lactose, ions of calcium and iron, immune protection, antimicrobial action, etc. However, in recent years, it has been found that milk proteins like casein are precursors of biologically active peptides. Аngiotensin — converting enzyme, opioid peptides which are opiate receptor agonists, anti–microbial peptides, peptides with immunomodulatory and hypocholesterolemic action, and peptides affecting motility have been found among the products of proteolytic degradation of ?-lactoglobulin, ?-laktoalbumin, lactoferrin and milk whey albumin. Also data on the possible participation of peptides from milk whey proteins in the implementation of the biological functions of both the assimilation of calcium, antioxidant effect, the regulation of appetite, anticarcinogenic are provided. The authors assume that the phenomenon of bioactive peptides formation could be considered as an additional function of natural food proteins, which gives advantages to the mammals and has a positive effect on their development in the postnatal period. Ways of bioactive peptides formation, their resistance to action of proteolytic enzymes, the ability to cross into the bloodstream and have biological effects have been also discussed. Up to date, only a few products with bioactive peptides from milk whey proteins are obtained. Further studies of their structure, mechanism of action, ways of formation and methods of isolation are required for their wider use. Formation of functional products based on bioactive peptides from milk whey proteins will allow efficient use of milk whey, which is often a

Body temperature and cardiac changes induced by peripherally administered oxytocin, vasopressin and the non-peptide oxytocin receptor agonist WAY 267,464: a biotelemetry study in rats

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Hicks, C; Ramos, L; Reekie, T; Misagh, G H; Narlawar, R; Kassiou, M; McGregor, I S

2014-01-01

Background and Purpose There is current interest in oxytocin (OT) as a possible therapeutic in psychiatric disorders. However, the usefulness of OT may be constrained by peripheral autonomic effects, which may involve an action at both OT and vasopressin V1A receptors. Here, we characterized the cardiovascular and thermoregulatory effects of OT, vasopressin (AVP) and the non-peptide OT receptor agonist WAY 267,464 in rats, and assessed the relative involvement of the OT and V1A receptors in these effects. Experimental Approach Biotelemetry in freely moving male Wistar rats was used to examine body temperature and heart rate after OT (0.01 – 1 mg kg−1; i.p.), AVP (0.001 – 0.1 mg kg−1; i.p.) or WAY 267,464 (10 and 100 mg kg−1; i.p.). The actions of the OT receptor antagonist Compound 25 (C25, 5 and 10 mg kg−1) and V1A receptor antagonist SR49059 (1 and 10 mg kg−1) were studied, as well as possible V1A receptor antagonist effects of WAY 267,464. Key Results OT and AVP dose-dependently reduced body temperature and heart rate. WAY 267,464 had similar, but more modest, effects. SR49059, but not C25, prevented the hypothermia and bradycardia induced by OT and AVP. WAY 267,464 (100 mg·kg−1) prevented the effects of OT, and to some extent AVP. Conclusions and Implications Peripherally administered OT and AVP have profound cardiovascular and thermoregulatory effects that appear to principally involve the V1A receptor rather than the OT receptor. Additionally, WAY 267,464 is not a simple OT receptor agonist, as it has functionally relevant V1A antagonist actions. PMID:24641248

Body temperature and cardiac changes induced by peripherally administered oxytocin, vasopressin and the non-peptide oxytocin receptor agonist WAY 267,464: a biotelemetry study in rats.

Science.gov (United States)

Hicks, C; Ramos, L; Reekie, T; Misagh, G H; Narlawar, R; Kassiou, M; McGregor, I S

2014-06-01

There is current interest in oxytocin (OT) as a possible therapeutic in psychiatric disorders. However, the usefulness of OT may be constrained by peripheral autonomic effects, which may involve an action at both OT and vasopressin V1A receptors. Here, we characterized the cardiovascular and thermoregulatory effects of OT, vasopressin (AVP) and the non-peptide OT receptor agonist WAY 267,464 in rats, and assessed the relative involvement of the OT and V1A receptors in these effects. Biotelemetry in freely moving male Wistar rats was used to examine body temperature and heart rate after OT (0.01 - 1 mg kg(-1); i.p.), AVP (0.001 - 0.1 mg kg(-1); i.p.) or WAY 267,464 (10 and 100 mg kg(-1); i.p.). The actions of the OT receptor antagonist Compound 25 (C25, 5 and 10 mg kg(-1)) and V1A receptor antagonist SR49059 (1 and 10 mg kg(-1)) were studied, as well as possible V1A receptor antagonist effects of WAY 267,464. OT and AVP dose-dependently reduced body temperature and heart rate. WAY 267,464 had similar, but more modest, effects. SR49059, but not C25, prevented the hypothermia and bradycardia induced by OT and AVP. WAY 267,464 (100 mg·kg(-1)) prevented the effects of OT, and to some extent AVP. Peripherally administered OT and AVP have profound cardiovascular and thermoregulatory effects that appear to principally involve the V1A receptor rather than the OT receptor. Additionally, WAY 267,464 is not a simple OT receptor agonist, as it has functionally relevant V1A antagonist actions. © 2014 The British Pharmacological Society.

Glucagon-like peptide-1 receptor ligand interactions: structural cross talk between ligands and the extracellular domain.

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Graham M West

Full Text Available Activation of the glucagon-like peptide-1 receptor (GLP-1R in pancreatic β-cells potentiates insulin production and is a current therapeutic target for the treatment of type 2 diabetes mellitus (T2DM. Like other class B G protein-coupled receptors (GPCRs, the GLP-1R contains an N-terminal extracellular ligand binding domain. N-terminal truncations on the peptide agonist generate antagonists capable of binding to the extracellular domain, but not capable of activating full length receptor. The main objective of this study was to use Hydrogen/deuterium exchange (HDX to identify how the amide hydrogen bonding network of peptide ligands and the extracellular domain of GLP-1R (nGLP-1R were altered by binding interactions and to then use this platform to validate direct binding events for putative GLP-1R small molecule ligands. The HDX studies presented here for two glucagon-like peptide-1 receptor (GLP-1R peptide ligands indicates that the antagonist exendin-4[9-39] is significantly destabilized in the presence of nonionic detergents as compared to the agonist exendin-4. Furthermore, HDX can detect stabilization of exendin-4 and exendin-4[9-39] hydrogen bonding networks at the N-terminal helix [Val19 to Lys27] upon binding to the N-terminal extracellular domain of GLP-1R (nGLP-1R. In addition we show hydrogen bonding network stabilization on nGLP-1R in response to ligand binding, and validate direct binding events with the extracellular domain of the receptor for putative GLP-1R small molecule ligands.

Physiology and Emerging Biochemistry of the Glucagon-Like Peptide-1 Receptor

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Francis S. Willard

2012-01-01

Full Text Available The glucagon-like peptide-1 (GLP-1 receptor is one of the best validated therapeutic targets for the treatment of type 2 diabetes mellitus (T2DM. Over several years, the accumulation of basic, translational, and clinical research helped define the physiologic roles of GLP-1 and its receptor in regulating glucose homeostasis and energy metabolism. These efforts provided much of the foundation for pharmaceutical development of the GLP-1 receptor peptide agonists, exenatide and liraglutide, as novel medicines for patients suffering from T2DM. Now, much attention is focused on better understanding the molecular mechanisms involved in ligand induced signaling of the GLP-1 receptor. For example, advancements in biophysical and structural biology techniques are being applied in attempts to more precisely determine ligand binding and receptor occupancy characteristics at the atomic level. These efforts should better inform three-dimensional modeling of the GLP-1 receptor that will help inspire more rational approaches to identify and optimize small molecule agonists or allosteric modulators targeting the GLP-1 receptor. This article reviews GLP-1 receptor physiology with an emphasis on GLP-1 induced signaling mechanisms in order to highlight new molecular strategies that help determine desired pharmacologic characteristics for guiding development of future nonpeptide GLP-1 receptor activators.

A novel dual GLP-1 and GIP incretin receptor agonist is neuroprotective in a mouse model of Parkinson’s disease by reducing chronic inflammation in the brain

OpenAIRE

Lijun, Cao; Li, Dongfang; Feng, Peng; Li, Lin; Xue, Guofang; Li, Guanglai; Holscher, Christian

2016-01-01

The incretins glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are growth factors. GLP-1 mimetics are on the market as treatments for type 2 diabetes. Both GLP-1 and GIP mimetics have shown neuroprotective properties in previous studies. In addition, the GLP-1 mimetic exendin-4 has shown protective effects in a clinical trial in Parkinson’s disease (PD) patients. Novel GLP-1/GIP dual-agonist peptides have been developed to treat diabetes. Here, we report ...

Characterization of peptide-oligonucleotide heteroconjugates by mass spectrometry.

OpenAIRE

Jensen, O N; Kulkarni, S; Aldrich, J V; Barofsky, D F

1996-01-01

Two peptide-oligothymidylic acids, prepared by joining an 11 residue synthetic peptide containing one internal carboxyl group (Asp side chain) to amino-linker-5'pdT6 and amino-linker-5'pdT10 oligonucleotides, were analyzed by matrix-assisted laser desorption/ionization (MALDI) on a linear time-of-flight mass spectrometer and by electrospray ionization (ESI) on a triple-quadrupole system. These synthetic compounds model peptide-nucleic acid heteroconjugates encountered in antisense research an...

Agonist-induced platelet reactivity correlates with bleeding in haemato-oncological patients.

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Batman, B; van Bladel, E R; van Hamersveld, M; Pasker-de Jong, P C M; Korporaal, S J A; Urbanus, R T; Roest, M; Boven, L A; Fijnheer, R

2017-11-01

Prophylactic platelet transfusions are administered to prevent bleeding in haemato-oncological patients. However, bleeding still occurs, despite these transfusions. This practice is costly and not without risk. Better predictors of bleeding are needed, and flow cytometric evaluation of platelet function might aid the clinician in identifying patients at risk of bleeding. This evaluation can be performed within the hour and is not hampered by low platelet count. Our objective was to assess a possible correlation between bleeding and platelet function in thrombocytopenic haemato-oncological patients. Inclusion was possible for admitted haemato-oncology patients aged 18 years and above. Furthermore, an expected need for platelet transfusions was necessary. Bleeding was graded according to the WHO bleeding scale. Platelet reactivity to stimulation by either adenosine diphosphate (ADP), cross-linked collagen-related peptide (CRP-xL), PAR1- or PAR4-activating peptide (AP) was measured using flow cytometry. A total of 114 evaluations were available from 21 consecutive patients. Platelet reactivity in response to stimulation by all four studied agonists was inversely correlated with significant bleeding. Odds ratios (OR) for bleeding were 0·28 for every unit increase in median fluorescence intensity (MFI) [95% confidence interval (CI) 0·11-0·73] for ADP; 0·59 [0·40-0·87] for CRP-xL; 0·59 [0·37-0·94] for PAR1-AP; and 0·43 [0·23-0·79] for PAR4-AP. The platelet count was not correlated with bleeding (OR 0·99 [0·96-1·02]). Agonist-induced platelet reactivity was significantly correlated to bleeding. Platelet function testing could provide a basis for a personalized transfusion regimen, in which platelet transfusions are limited to those at risk of bleeding. © 2017 International Society of Blood Transfusion.

Mody-3: novel HNF1A mutation and the utility of glucagon-like peptide (GLP)-1 receptor agonist therapy.

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Docena, Maricor K; Faiman, Charles; Stanley, Christine M; Pantalone, Kevin M

2014-02-01

An estimated 1 to 2% of cases of diabetes mellitus have a monogenic basis; however, delayed diagnosis and misdiagnosis as type 1 and 2 diabetes are common. Correctly identifying the molecular basis of an individual's diabetes may significantly alter the management approach to both the patient and his or her relatives. We describe a case of mature onset diabetes of the young (MODY) with sufficient evidence to support the classification of a novel HNF1A (hepatocyte nuclear factor-1-α) mutation as a cause of MODY-3. A 21-year-old Caucasian female presented to our office with a diagnosis of noninsulin-dependent diabetes mellitus (NIDDM) at age 10; glycemia was initially managed with oral antidiabetic (OAD) agents and insulin detemir. The patient reported a strong family history of early-onset NIDDM in both her mother and maternal grandmother, both of whom eventually required insulin therapy to control glycemia. The patient's medical and family history were highly suggestive of maturity-onset diabetes of the young (MODY), and genetic testing was performed. Genetic screening detected a mutation p. Arg200Trp in the HNF1A gene in the patient, her mother, and maternal grandmother, suggesting a diagnosis of MODY-3. This finding resulted in a change of antidiabetic therapy in all 3 patients, including the addition of once-daily liraglutide therapy, which helped improve their glycemic control. Our case report supports the classification of the p. Arg200Trp mutation as a cause of MODY-3. The findings also suggest that glucagon-like peptide-1 (GLP-1) receptor agonist therapy may be of value in managing glycemia in patients with MODY-3.

Endomorphin-2: a biased agonist at the μ-opioid receptor.

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Rivero, Guadalupe; Llorente, Javier; McPherson, Jamie; Cooke, Alex; Mundell, Stuart J; McArdle, Craig A; Rosethorne, Elizabeth M; Charlton, Steven J; Krasel, Cornelius; Bailey, Christopher P; Henderson, Graeme; Kelly, Eamonn

2012-08-01

Previously we correlated the efficacy for G protein activation with that for arrestin recruitment for a number of agonists at the μ-opioid receptor (MOPr) stably expressed in HEK293 cells. We suggested that the endomorphins (endomorphin-1 and -2) might be biased toward arrestin recruitment. In the present study, we investigated this phenomenon in more detail for endomorphin-2, using endogenous MOPr in rat brain as well as MOPr stably expressed in HEK293 cells. For MOPr in neurons in brainstem locus ceruleus slices, the peptide agonists [d-Ala(2),N-Me-Phe(4),Gly(5)-ol]-enkephalin (DAMGO) and endomorphin-2 activated inwardly rectifying K(+) current in a concentration-dependent manner. Analysis of these responses with the operational model of pharmacological agonism confirmed that endomorphin-2 had a much lower operational efficacy for G protein-mediated responses than did DAMGO at native MOPr in mature neurons. However, endomorphin-2 induced faster desensitization of the K(+) current than did DAMGO. In addition, in HEK293 cells stably expressing MOPr, the ability of endomorphin-2 to induce phosphorylation of Ser375 in the COOH terminus of the receptor, to induce association of arrestin with the receptor, and to induce cell surface loss of receptors was much more efficient than would be predicted from its efficacy for G protein-mediated signaling. Together, these results indicate that endomorphin-2 is an arrestin-biased agonist at MOPr and the reason for this is likely to be the ability of endomorphin-2 to induce greater phosphorylation of MOPr than would be expected from its ability to activate MOPr and to induce activation of G proteins.

The proteolytically stable peptidomimetic Pam-(Lys-βNSpe)6-NH2 selectively inhibits human neutrophil activation via formyl peptide receptor 2.

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Skovbakke, Sarah Line; Heegaard, Peter M H; Larsen, Camilla J; Franzyk, Henrik; Forsman, Huamei; Dahlgren, Claes

2015-01-15

Immunomodulatory host defense peptides (HDPs) are considered to be lead compounds for novel anti-sepsis and anti-inflammatory agents. However, development of drugs based on HDPs has been hampered by problems with toxicity and low bioavailability due to in vivo proteolysis. Here, a subclass of proteolytically stable HDP mimics consisting of lipidated α-peptide/β-peptoid oligomers was investigated for their effect on neutrophil function. The most promising compound, Pam-(Lys-βNSpe)6-NH2, was shown to inhibit formyl peptide receptor 2 (FPR2) agonist-induced neutrophil granule mobilization and release of reactive oxygen species. The potency of Pam-(Lys-βNSpe)6-NH2 was comparable to that of PBP10, the most potent FPR2-selective inhibitor known. The immunomodulatory effects of structural analogs of Pam-(Lys-βNSpe)6-NH2 emphasized the importance of both the lipid and peptidomimetic parts. By using imaging flow cytometry in primary neutrophils and FPR-transfected cell lines, we found that a fluorescently labeled analog of Pam-(Lys-βNSpe)6-NH2 interacted selectively with FPR2. Furthermore, the interaction between Pam-(Lys-βNSpe)6-NH2 and FPR2 was found to prevent binding of the FPR2-specific activating peptide agonist Cy5-WKYMWM, while the binding of an FPR1-selective agonist was not inhibited. To our knowledge, Pam-(Lys-βNSpe)6-NH2 is the first HDP mimic found to inhibit activation of human neutrophils via direct interaction with FPR2. Hence, we consider Pam-(Lys-βNSpe)6-NH2 to be a convenient tool in the further dissection of the role of FPR2 in inflammation and homeostasis as well as for investigation of the importance of neutrophil stimulation in anti-infective therapy involving HDPs. Copyright © 2014 Elsevier Inc. All rights reserved.

Adjunctive Role of Glucagon-Like Peptide-1 Receptor Agonists in the Management of Type 1 Diabetes Mellitus.

Science.gov (United States)

Harris, Kira B; Boland, Cassie L

2016-09-01

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are commonly used in combination with insulin to manage type 2 diabetes mellitus, and four agents are currently approved for this indication: exenatide, liraglutide, dulaglutide, and albiglutide. The distinctive properties of GLP-1 RAs-potential hemoglobin A1c (A1C) reduction, weight loss, potential to reduce insulin doses, and lower hypoglycemia risk-have made these agents potential treatment options for patients with type 1 diabetes mellitus (T1DM) as well. These positive effects are due to glucose-dependent insulin secretion, reduced glucagon secretion, increased satiety, and delayed gastric emptying. Patients with T1DM are unable to suppress glucagon during meals, which contributes to postprandial hyperglycemia and may be improved with GLP-1 therapy. In this review, we evaluated the available literature on the clinical efficacy and safety of GLP-1 RAs in patients with T1DM. We conducted a search of the PubMed (1966-May 2016) and Ovid (1946-May 2016) databases. Abstracts presented at the scientific and clinical sessions of the American Diabetes Association and the American Association of Clinical Endocrinologists were also searched. The references of the published articles were also reviewed to identify additional studies appropriate for inclusion. All identified articles published in English were evaluated. Studies were included if they evaluated the clinical use or safety of GLP-1 RAs in patients with T1DM. Twelve studies were included, with four evaluating exenatide, one evaluating exenatide extended release, and seven evaluating liraglutide. Both exenatide and liraglutide showed significant reductions in hemoglobin A1C, plasma glucose concentration, body weight, and insulin doses when administered to patients with T1DM already receiving insulin therapy, without increasing the occurrence of hypoglycemia. Adverse effects were mostly gastrointestinal in nature but were mild and transient. Patients who may

Virtual screening using combinatorial cyclic peptide libraries reveals protein interfaces readily targetable by cyclic peptides.

Science.gov (United States)

Duffy, Fergal J; O'Donovan, Darragh; Devocelle, Marc; Moran, Niamh; O'Connell, David J; Shields, Denis C

2015-03-23

Protein-protein and protein-peptide interactions are responsible for the vast majority of biological functions in vivo, but targeting these interactions with small molecules has historically been difficult. What is required are efficient combined computational and experimental screening methods to choose among a number of potential protein interfaces worthy of targeting lead macrocyclic compounds for further investigation. To achieve this, we have generated combinatorial 3D virtual libraries of short disulfide-bonded peptides and compared them to pharmacophore models of important protein-protein and protein-peptide structures, including short linear motifs (SLiMs), protein-binding peptides, and turn structures at protein-protein interfaces, built from 3D models available in the Protein Data Bank. We prepared a total of 372 reference pharmacophores, which were matched against 108,659 multiconformer cyclic peptides. After normalization to exclude nonspecific cyclic peptides, the top hits notably are enriched for mimetics of turn structures, including a turn at the interaction surface of human α thrombin, and also feature several protein-binding peptides. The top cyclic peptide hits also cover the critical "hot spot" interaction sites predicted from the interaction crystal structure. We have validated our method by testing cyclic peptides predicted to inhibit thrombin, a key protein in the blood coagulation pathway of important therapeutic interest, identifying a cyclic peptide inhibitor with lead-like activity. We conclude that protein interfaces most readily targetable by cyclic peptides and related macrocyclic drugs may be identified computationally among a set of candidate interfaces, accelerating the choice of interfaces against which lead compounds may be screened.

Structural basis for the enhanced activity of cyclic antimicrobial peptides : The case of BPC194

NARCIS (Netherlands)

Mika, Jacek T.; Moiset, Gemma; Cirac, Anna D.; Feliu, Lidia; Bardaji, Eduard; Planas, Marta; Sengupta, Durba; Marrink, Siewert J.; Poolman, Bert

We report the molecular basis for the differences in activity of cyclic and linear antimicrobial peptides. We iteratively performed atomistic molecular dynamics simulations and biophysical measurements to probe the interaction of a cyclic antimicrobial peptide and its inactive linear analogue with

Comparative biodistribution of 12 {sup 111}In-labelled gastrin/CCK2 receptor-targeting peptides

Energy Technology Data Exchange (ETDEWEB)

Laverman, Peter; Joosten, Lieke; Eek, Annemarie; Roosenburg, Susan; Oyen, Wim J.G.; Boerman, Otto C. [Radboud University Nijmegen Medical Centre, Department of Nuclear Medicine, Nijmegen (Netherlands); Peitl, Petra Kolenc [University Medical Centre Ljubljana, Department of Nuclear Medicine, Ljubljana (Slovenia); Maina, Theodosia [National Center for Scientific Research Demokritos, Molecular Radiopharmacy, Institute of Radioisotopes-Radiodiagnostic Products, Athens (Greece); Maecke, Helmut [University Hospital Freiburg, Department of Nuclear Medicine, Freiburg (Germany); Aloj, Luigi [Fondazione ' ' G. Pascale' ' , Department of Nuclear Medicine, Istituto Nazionale Tumouri, Naples (Italy); Guggenberg, Elisabeth von [Innsbruck Medical University, Department of Nuclear Medicine, Innsbruck (Austria); Sosabowski, Jane K. [Queen Mary, University of London, Centre for Molecular Oncology and Imaging, Institute of Cancer, Barts and The London School of Medicine and Dentistry, London (United Kingdom); Jong, Marion de [Erasmus MC, Department of Nuclear Medicine, Rotterdam (Netherlands); Reubi, Jean-Claude [University of Berne, Institute of Pathology, Berne (Switzerland)

2011-08-15

Cholecystokinin 2 (CCK-2) receptor overexpression has been demonstrated in various tumours such as medullary thyroid carcinomas and small-cell lung cancers. Due to this high expression, CCK-2 receptors might be suitable targets for radionuclide imaging and/or radionuclide therapy. Several CCK-2 receptor-binding radiopeptides have been developed and some have been tested in patients. Here we aimed to compare the in vivo tumour targeting properties of 12 {sup 111}In-labelled 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-conjugated gastrin/CCK2 receptor-binding peptides. Two CCK8-based peptides and ten gastrin-based peptide analogues were tested. All peptides were conjugated with DOTA and labelled with {sup 111}In. Biodistribution studies were performed in mice with subcutaneous CCK2/gastrin receptor-expressing tumours and with receptor-negative tumours contralaterally. Biodistribution was studied by counting dissected tissues at 1 and 4 h after injection. Both the CCK analogues displayed relatively low tumour uptake (approximately 2.5%ID/g) as compared to minigastrin analogues. Two linear minigastrin peptides (MG0 and sargastrin) displayed moderate tumour uptake at both 1 and 4 h after injection, but also very high kidney uptake (both higher than 48%ID/g). The linear MG11, lacking the penta-Glu sequence, showed lower tumour uptake and also low kidney uptake. Varying the N-terminal Glu residues in the minigastrin analogues led to improved tumour targeting properties, with PP-F11 displaying the optimal biodistribution. Besides the monomeric linear peptides, a cyclized peptide and a divalent peptide were tested. Based on these studies, optimal peptides for peptide receptor radionuclide targeting of CCK2/gastrin receptor-expressing tumours were the linear minigastrin analogue with six D-Glu residues (PP-F11), the divalent analogue MGD5 and the cyclic peptide cyclo-MG1. These peptides combined high tumour uptake with low kidney retention, and may

Epobis is a Nonerythropoietic and Neuroprotective Agonist of the Erythropoietin Receptor with Anti-Inflammatory and Memory Enhancing Effects

Directory of Open Access Journals (Sweden)

Oksana Dmytriyeva

2016-01-01

Full Text Available The cytokine erythropoietin (EPO stimulates proliferation and differentiation of erythroid progenitor cells. Moreover, EPO has neuroprotective, anti-inflammatory, and antioxidative effects, but the use of EPO as a neuroprotective agent is hampered by its erythropoietic activity. We have recently designed the synthetic, dendrimeric peptide, Epobis, derived from the sequence of human EPO. This peptide binds the EPO receptor and promotes neuritogenesis and neuronal cell survival. Here we demonstrate that Epobis in vitro promotes neuritogenesis in primary motoneurons and has anti-inflammatory effects as demonstrated by its ability to decrease TNF release from activated AMJ2-C8 macrophages and rat primary microglia. When administered systemically Epobis is detectable in both plasma and cerebrospinal fluid, demonstrating that the peptide crosses the blood-brain barrier. Importantly, Epobis is not erythropoietic, but systemic administration of Epobis in rats delays the clinical signs of experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis, and the peptide has long-term, but not short-term, effects on working memory, detected as an improved social memory 3 days after administration. These data reveal Epobis to be a nonerythropoietic and neuroprotective EPO receptor agonist with anti-inflammatory and memory enhancing properties.

Corticotropin-releasing factor peptide antagonists: design, characterization and potential clinical relevance.

Science.gov (United States)

Rivier, Jean E; Rivier, Catherine L

2014-04-01

Elusive for more than half a century, corticotropin-releasing factor (CRF) was finally isolated and characterized in 1981 from ovine hypothalami and shortly thereafter, from rat brains. Thirty years later, much has been learned about the function and localization of CRF and related family members (Urocortins 1, 2 and 3) and their 2 receptors, CRF receptor type 1 (CRFR1) and CRF receptor type 2 (CRFR2). Here, we report the stepwise development of peptide CRF agonists and antagonists, which led to the CRFR1 agonist Stressin1; the long-acting antagonists Astressin2-B which is specific for CRFR2; and Astressin B, which binds to both CRFR1 and CRFR2.This analog has potential for the treatment of CRF-dependent diseases in the periphery, such as irritable bowel syndrome. Copyright © 2013 Elsevier Inc. All rights reserved.

Renal effects of DPP-4 inhibitor sitagliptin or GLP-1 receptor agonist liraglutide in overweight patients with type 2 diabetes : A 12-week, randomized, double-blind, placebo-controlled trial

NARCIS (Netherlands)

Tonneijck, Lennart; Smits, Mark M.; Muskiet, Marcel H A; Hoekstra, Trynke; Kramer, Mark H H; Danser, A. H Jan; Ter Wee, Piet M.; Diamant, Michaela; Joles, Jaap A.; Van Raalte, Daniël H.

2016-01-01

OBJECTIVE To investigate effects of dipeptidyl peptidase-4 inhibitor (DPP-4I) sitagliptin or glucagon-like peptide 1 (GLP-1) receptor agonist liraglutide treatment on renal hemodynamics, tubular functions, and markers of renal damage in overweight patients with type 2 diabetes without chronic kidney

Non-nucleotide Agonists Triggering P2X7 Receptor Activation and Pore Formation

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Francesco Di Virgilio

2018-02-01

Full Text Available The P2X7 receptor (P2X7R is a ligand-gated plasma membrane ion channel belonging to the P2X receptor subfamily activated by extracellular nucleotides. General consensus holds that the physiological (and maybe the only agonist is ATP. However, scattered evidence generated over the last several years suggests that ATP might not be the only agonist, especially at inflammatory sites. Solid data show that NAD+ covalently modifies the P2X7R of mouse T lymphocytes, thus lowering the ATP threshold for activation. Other structurally unrelated agents have been reported to activate the P2X7R via a poorly understood mechanism of action: (a the antibiotic polymyxin B, possibly a positive allosteric P2X7R modulator, (b the bactericidal peptide LL-37, (c the amyloidogenic β peptide, and (d serum amyloid A. Some agents, such as Alu-RNA, have been suggested to activate the P2X7R acting on the intracellular N- or C-terminal domains. Mode of P2X7R activation by these non-nucleotide ligands is as yet unknown; however, these observations raise the intriguing question of how these different non-nucleotide ligands may co-operate with ATP at inflammatory or tumor sites. New information obtained from the cloning and characterization of the P2X7R from exotic mammalian species (e.g., giant panda and data from recent patch-clamp studies are strongly accelerating our understanding of P2X7R mode of operation, and may provide hints to the mechanism of activation of P2X7R by non-nucleotide ligands.

The epileptogenic spectrum of opiate agonists.

Science.gov (United States)

Snead, O C; Bearden, L J

1982-11-01

The present authors gave mu, delta, kappa, epsilon and sigma opiate receptor agonists intracerebroventricularly to rats both singly and in combination while monitoring the electroencephalogram from cortical and depth electrodes. Dose-response curves were plotted with naloxone against the changes produced by each agonist, and the effect of a number of anticonvulsant drugs on agonist-induced seizures was ascertained. Each opiate agonist produced a different seizure pattern with a different naloxone dose-response curve and anticonvulsant profile. The order of convulsive potency was epsilon greater than delta greater than mu greater than sigma much greater than kappa. Petit mal-like seizure activity was unique to the delta agonist, leucine-enkephalin, while only the mu agonist, morphine produced generalized convulsive seizures. These experiments raise the possibility that opiate systems in the brain may be involved in the pathogenesis of a wide spectrum of seizure disorders.

Acylation of Therapeutic Peptides

DEFF Research Database (Denmark)

Trier, Sofie; Henriksen, Jonas Rosager; Jensen, Simon Bjerregaard

) , which promotes intestinal growth and is used to treat bowel disorders such as inflammatory bowel diseases and short bowel syndrome, and the 32 amino acid salmon calcitonin (sCT), which lowers blood calcium and is employed in the treatment of post-menopausal osteoporosis and hypercalcemia. The two...... peptides are similar in size and structure, but oppositely charged at physiological pH. Both peptides were acylated with linear acyl chains of systematically increasing length, where sCT was furthermore acylated at two different positions on the peptide backbone. For GLP-2, we found that increasing acyl...... remained optimal overall. The results indicate that rational acylation of GLP-2 can increase its in vitro intestinal absorption, alone or in combination with permeation enhancers, and are consistent with the initial project hypothesis. For sCT, an unpredicted effect of acylation largely superseded...

Melanocortin Receptor Agonists Facilitate Oxytocin-Dependent Partner Preference Formation in the Prairie Vole.

Science.gov (United States)

Modi, Meera E; Inoue, Kiyoshi; Barrett, Catherine E; Kittelberger, Kara A; Smith, Daniel G; Landgraf, Rainer; Young, Larry J

2015-07-01

The central melanocortin (MC) system has been widely studied for its effects on food intake and sexual behavior. However, the MC system, and more specifically the MC4 receptor (MC4R), also interacts with neurochemical systems that regulate socioemotional behaviors, including oxytocin (OT) and dopamine. In monogamous prairie voles, OT and dopamine interact to promote partner preference formation, a laboratory measure of an enduring social bond between mates. Here we investigated the effects of MC receptor activation on partner preference formation in prairie voles, as well as the interaction between the MC and OT systems during this process. Peripheral administration of the brain penetrant MC3/4R receptor peptide agonist, Melanotan II (MTII), and the highly selective, small-molecule MC4R agonist, Pf-446687, enhanced partner preference formation in the prairie vole, but not in the non-monogamous meadow vole. MTII-induced partner preferences were enduring, as they were present 1 week after drug manipulation. The prosocial effects of MCR agonists may be mediated, in part, through modulation of OT, as coadministration of an OT receptor antagonist prevented MTII-induced partner preferences. MTII also selectively activated hypothalamic OT neurons and potentiated central OT release. As OT has been shown to enhance some aspects of social cognition in humans, our data suggest that the MC4R may be a viable therapeutic target for enhancing social function in psychiatric disorders, including autism spectrum disorders and schizophrenia, potentially through activation of the OT system.

Synthesis and evaluation of amphiphilic peptides as nanostructures and drug delivery tools

Science.gov (United States)

Sayeh, Naser Ali

conjugates although one limitation lies in the effort of controlling the rate of drug release. The encapsulated or complexed drugs tend to be released rapidly (before reaching the target site) and in the dendrimer--drug conjugates, it is the chemical linkage that controls the drug release. Thus, future studies in this field are urgently required to create more efficient and stable biomaterials. Peptides are considered as efficient vectors for achieving optimal cellular uptake. The potential use of peptides as drug delivery vectors received much attention by the discovery of several cell-penetrating peptides (CPPs). The first CPPs discovered in 1988, that were sequences from HIV-1 encoded TAT protein, TAT (48--60), and penetrated very efficiently through cell membranes of cultured mammalian cells. CPPs are a class of diverse peptides, typically with 8--25 amino acids, and unlike most peptides, they can cross the cellular membrane with more efficiency. CPPs have also shown to undergo self-assembly and generate nanostructures. The generation of self-assembled peptides and nanostructures occur through various types of interactions between functional groups of amino acid residues, such as electrostatic, hydrophobic, and hydrogen bonding. Appropriate design and functionalization of peptides are critical for generating nanostructures. Chemically CPPs are classified into two major groups: linear and cyclic peptides. It has been previously reported that linear peptides containing hydrophilic and hydrophobic amino acids could act as membrane protein stabilizers. These compounds are short hydrophilic or amphiphilic peptides that have positively charged amino acids, such as arginine, lysine or histidine, which can interact with the negative charge phospholipids layer on the cell membrane and translocate the cargo into the cells. Conjugation to cationic linear CPPs, such as TAT, penetratin, or oligoarginine efficiently improves the cellular uptake of large hydrophilic molecules, but the

Software-aided approach to investigate peptide structure and metabolic susceptibility of amide bonds in peptide drugs based on high resolution mass spectrometry.

Directory of Open Access Journals (Sweden)

Tatiana Radchenko

Full Text Available Interest in using peptide molecules as therapeutic agents due to high selectivity and efficacy is increasing within the pharmaceutical industry. However, most peptide-derived drugs cannot be administered orally because of low bioavailability and instability in the gastrointestinal tract due to protease activity. Therefore, structural modifications peptides are required to improve their stability. For this purpose, several in-silico software tools have been developed such as PeptideCutter or PoPS, which aim to predict peptide cleavage sites for different proteases. Moreover, several databases exist where this information is collected and stored from public sources such as MEROPS and ExPASy ENZYME databases. These tools can help design a peptide drug with increased stability against proteolysis, though they are limited to natural amino acids or cannot process cyclic peptides, for example. We worked to develop a new methodology to analyze peptide structure and amide bond metabolic stability based on the peptide structure (linear/cyclic, natural/unnatural amino acids. This approach used liquid chromatography / high resolution, mass spectrometry to obtain the analytical data from in vitro incubations. We collected experimental data for a set (linear/cyclic, natural/unnatural amino acids of fourteen peptide drugs and four substrate peptides incubated with different proteolytic media: trypsin, chymotrypsin, pepsin, pancreatic elastase, dipeptidyl peptidase-4 and neprilysin. Mass spectrometry data was analyzed to find metabolites and determine their structures, then all the results were stored in a chemically aware manner, which allows us to compute the peptide bond susceptibility by using a frequency analysis of the metabolic-liable bonds. In total 132 metabolites were found from the various in vitro conditions tested resulting in 77 distinct cleavage sites. The most frequent observed cleavage sites agreed with those reported in the literature. The

Synthesis of a cyclic fibrin-like peptide and its analysis by fast atom bombardment mass spectrometry

International Nuclear Information System (INIS)

Young, J.D.; Costello, C.E.; Langenhove, A. van; Haber, E.; Matsueda, G.R.

1983-01-01

For immunochemical purposes, a cyclic 12 peptide was synthesized to model the γ-γ-chain cross-link site in human fibrin. The model was based upon the structure proposed by Chen and Doolittle which is characterized by two reciprocating epsilon-(γ-Glu)Lys bonds between adjacent fibrin γ-chains oriented in an antiparallel manner. To achieve the antiparallel orientation of the peptide backbone, Pro and Gly were inserted at positions 6 and 7 of the linear 12-peptide: acetyl-Gly-Glu-Gln-His-His-Pro-Gly-Gly-Gly-Ala-Lys-Gly-amide. The insertions were made to facilitate a reverse turn of the peptide during the last synthetic step, which was formation of the epsilon-(γ-Glu)Lys bond between Glu at position 2 and Lys at position 11 with diphenylphosphorylazide. The resulting cyclic peptide represented half of the symmetrical cross-linked region in clotted fibrin. Following purification by HPLC, both linear and cyclic 12-peptides were analyzed by fast atom bombardment mass spectrometry. Abundant molecular protonated ions were observed for both peptides. In addition, the amino acid sequence of the linear peptide and the location of the epsilon-(γ-Glu)Lys bond in the cyclized peptide could be verified. (author)

Structural changes of the ligand and of the receptor alters the receptor preference for neutrophil activating peptides starting with a 3 formylmethionyl group

DEFF Research Database (Denmark)

Forsman, Huamei; Winther, Malene; Gabl, Michael

2015-01-01

Pathogenic Staphylococcus aureus strains produce N-formylmethionyl containing peptides, of which the tetrapeptide fMIFL is a potent activator of the neutrophil formyl peptide receptor 1 (FPR1) and the PSMα2 peptide is a potent activator of the closely related FPR2. Variants derived from these two...... peptide activators were used to disclose the structural determinants for receptor interaction. Removal of five amino acids from the C-terminus of PSMα2 gave rise to a peptide that had lost the receptor-independent neutrophil permeabilizing effect, whereas neutrophil activation capacity as well as its...... preference for FPR2 was retained. Shorter peptides, PSMα21–10 and PSMα21–5, activate neutrophils, but the receptor preference for these peptides was switched to FPR1. The fMIFL-PSM5–16 peptide, in which the N-terminus of PSMα21–16 was replaced by the sequence fMIFL, was a dual agonist for FPR1/FPR2, whereas...

Evaluation of partial beta-adrenoceptor agonist activity.

Science.gov (United States)

Lipworth, B J; Grove, A

1997-01-01

A partial beta-adrenoceptor (beta-AR) agonist will exhibit opposite agonist and antagonist activity depending on the prevailing degree of adrenergic tone or the presence of a beta-AR agonist with higher intrinsic activity. In vivo partial beta-AR agonist activity will be evident at rest with low endogenous adrenergic tone, as for example with chronotropicity (beta 1/beta 2), inotropicity (beta 1) or peripheral vasodilatation and finger tremor (beta 2). beta-AR blocking drugs which have partial agonist activity may exhibit a better therapeutic profile when used for hypertension because of maintained cardiac output without increased systemic vascular resistance, along with an improved lipid profile. In the presence of raised endogenous adrenergic tone such as exercise or an exogenous full agonist, beta-AR subtype antagonist activity will become evident in terms of effects on exercise induced heart rate (beta 1) and potassium (beta 2) responses. Reduction of exercise heart rate will occur to a lesser degree in the case of a beta-adrenoceptor blocker with partial beta 1-AR agonist activity compared with a beta-adrenoceptor blocker devoid of partial agonist activity. This may result in reduced therapeutic efficacy in the treatment of angina on effort when using beta-AR blocking drugs with partial beta 1-AR agonist activity. Effects on exercise hyperkalaemia are determined by the balance between beta 2-AR partial agonist activity and endogenous adrenergic activity. For predominantly beta 2-AR agonist such as salmeterol and salbutamol, potentiation of exercise hyperkalaemia occurs. For predominantly beta 2-AR antagonists such as carteolol, either potentiation or attenuation of exercise hyperkalaemia occurs at low and high doses respectively. beta 2-AR partial agonist activity may also be expressed as antagonism in the presence of an exogenous full agonist, as for example attenuation of fenoterol induced responses by salmeterol. Studies are required to investigate whether

A Tetrameric Peptide Derived from Bovine Lactoferricin Exhibits Specific Cytotoxic Effects against Oral Squamous-Cell Carcinoma Cell Lines.

Science.gov (United States)

Solarte, Víctor A; Rosas, Jaiver E; Rivera, Zuly J; Arango-Rodríguez, Martha L; García, Javier E; Vernot, Jean-Paul

2015-01-01

Several short linear peptides derived from cyclic bovine lactoferricin were synthesized and tested for their cytotoxic effect against the oral cavity squamous-cell carcinoma (OSCC) cell lines CAL27 and SCC15. As a control, an immortalized and nontumorigenic cell line, Het-1A, was used. Linear peptides based on the RRWQWR core sequence showed a moderate cytotoxic effect and specificity towards tumorigenic cells. A tetrameric peptide, LfcinB(20-25)4, containing the RRWQWR motif, exhibited greater cytotoxic activity (>90%) in both OSCC cell lines compared to the linear lactoferricin peptide or the lactoferrin protein. Additionally, this tetrameric peptide showed the highest specificity towards tumorigenic cells among the tested peptides. Interestingly, this effect was very fast, with cell shrinkage, severe damage to cell membrane permeability, and lysis within one hour of treatment. Our results are consistent with a necrotic effect rather than an apoptotic one and suggest that this tetrameric peptide could be considered as a new candidate for the therapeutic treatment of OSCC.

Vitamin D receptor agonists inhibit pro-inflammatory cytokine production from the respiratory epithelium in cystic fibrosis.

LENUS (Irish Health Repository)

McNally, P

2011-07-22

BACKGROUND: 1,25-Dihydroxycholecalciferol (1,25(OH)(2)D(3)) has been shown to mitigate epithelial inflammatory responses after antigen exposure. Patients with cystic fibrosis (CF) are at particular risk for vitamin D deficiency. This may contribute to the exaggerated inflammatory response to pulmonary infection in CF. METHODS: CF respiratory epithelial cell lines were exposed to Pseudomonas aeruginosa lipopolysaccharide (LPS) and Pseudomonas conditioned medium (PCM) in the presence or absence of 1,25(OH)(2)D(3) or a range of vitamin D receptor (VDR) agonists. Levels of IL-6 and IL-8 were measured in cell supernatants, and cellular total and phosphorylated IκBα were determined. Levels of human cathelicidin antimicrobial peptide (hCAP18) mRNA and protein were measured in cells after treatment with 1,25(OH)(2)D(3). RESULTS: Pretreatment with 1,25(OH)(2)D(3) was associated with significant reductions in IL-6 and IL-8 protein secretion after antigen exposure, a finding reproduced with a range of low calcaemic VDR agonists. 1,25(OH)(2)D(3) treatment led to a decrease in IκBα phosphorylation and increased total cellular IκBα. Treatment with 1,25(OH)(2)D(3) was associated with an increase in hCAP18\\/LL-37 mRNA and protein levels. CONCLUSIONS: Both 1,25(OH)(2)D(3) and other VDR agonists significantly reduce the pro-inflammatory response to antigen challenge in CF airway epithelial cells. VDR agonists have significant therapeutic potential in CF.

[Safety and tolerability of GLP-1 receptor agonists].

Science.gov (United States)

Soldevila, Berta; Puig-Domingo, Manel

2014-09-01

Glucagon-like peptide-1 receptor agonists (GLP-1ra) are a new group of drugs with a glucose-lowering action due to their incretin effect. The GLP-1 receptor is expressed in various human tissues, which could be related to the pleiotropic effects of human GLP-1, as well as to the adverse effects described in patients treated with GLP-1ra. The risk of hypoglycaemia is low, which is one of the main considerations in the safety of this family of compounds and is also important to patients with diabetes. The most frequent adverse effect is nausea, which usually occurs at the start of treatment and is transient in 20-60% of affected patients. This article also reviews the information available on antibody formation, the potential effect on the thyroid gland, and the controversial association between this group of drugs with pancreatitis and cancer. Copyright © 2014 Elsevier España, S.L.U. All rights reserved.

RFamide Peptides: Structure, Function, Mechanisms and Pharmaceutical Potential

Science.gov (United States)

Findeisen, Maria; Rathmann, Daniel; Beck-Sickinger, Annette G.

2011-01-01

Different neuropeptides, all containing a common carboxy-terminal RFamide sequence, have been characterized as ligands of the RFamide peptide receptor family. Currently, five subgroups have been characterized with respect to their N-terminal sequence and hence cover a wide pattern of biological functions, like important neuroendocrine, behavioral, sensory and automatic functions. The RFamide peptide receptor family represents a multiligand/multireceptor system, as many ligands are recognized by several GPCR subtypes within one family. Multireceptor systems are often susceptible to cross-reactions, as their numerous ligands are frequently closely related. In this review we focus on recent results in the field of structure-activity studies as well as mutational exploration of crucial positions within this GPCR system. The review summarizes the reported peptide analogs and recently developed small molecule ligands (agonists and antagonists) to highlight the current understanding of the pharmacophoric elements, required for affinity and activity at the receptor family. Furthermore, we address the biological functions of the ligands and give an overview on their involvement in physiological processes. We provide insights in the knowledge for the design of highly selective ligands for single receptor subtypes to minimize cross-talk and to eliminate effects from interactions within the GPCR system. This will support the drug development of members of the RFamide family.

RFamide Peptides: Structure, Function, Mechanisms and Pharmaceutical Potential

Directory of Open Access Journals (Sweden)

Maria Findeisen

2011-09-01

Full Text Available Different neuropeptides, all containing a common carboxy-terminal RFamide sequence, have been characterized as ligands of the RFamide peptide receptor family. Currently, five subgroups have been characterized with respect to their N-terminal sequence and hence cover a wide pattern of biological functions, like important neuroendocrine, behavioral, sensory and automatic functions. The RFamide peptide receptor family represents a multiligand/multireceptor system, as many ligands are recognized by several GPCR subtypes within one family. Multireceptor systems are often susceptible to cross-reactions, as their numerous ligands are frequently closely related. In this review we focus on recent results in the field of structure-activity studies as well as mutational exploration of crucial positions within this GPCR system. The review summarizes the reported peptide analogs and recently developed small molecule ligands (agonists and antagonists to highlight the current understanding of the pharmacophoric elements, required for affinity and activity at the receptor family. Furthermore, we address the biological functions of the ligands and give an overview on their involvement in physiological processes. We provide insights in the knowledge for the design of highly selective ligands for single receptor subtypes to minimize cross-talk and to eliminate effects from interactions within the GPCR system. This will support the drug development of members of the RFamide family.

Effects of gastric inhibitory polypeptide, glucagon-like peptide-1 and glucagon-like peptide-1 receptor agonists on Bone Cell Metabolism

DEFF Research Database (Denmark)

Hansen, Morten S S; Tencerova, Michaela; Frølich, Jacob

2018-01-01

The relationship between gut and skeleton is increasingly recognised as part of the integrated physiology of the whole organism. The incretin hormones gastric inhibitory polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are secreted from the intestine in response to nutrient intake and exhibi......-clinical investigations, clinical trials are needed to clarify if similar effects are present and clinically relevant in humans. This article is protected by copyright. All rights reserved....

Toll-like receptor-2 agonist-allergen coupling efficiently redirects Th2 cell responses and inhibits allergic airway eosinophilia.

Science.gov (United States)

Krishnaswamy, Jayendra Kumar; Jirmo, Adan Chari; Baru, Abdul Mannan; Ebensen, Thomas; Guzmán, Carlos A; Sparwasser, Tim; Behrens, Georg M N

2012-12-01

Toll-like receptor (TLR) agonists beneficially modulate allergic airway inflammation. However, the efficiency of TLR agonists varies considerably, and their exact cellular mechanisms (especially of TLR 2/6 agonists) are incompletely understood. We investigated at a cellular level whether the administration of the pharmacologically improved TLR2/6 agonist S-[2,3-bispalmitoyiloxy-(2R)-propyl]-R-cysteinyl-amido-monomethoxy polyethylene glycol (BPP) conjugated to antigenic peptide (BPP-OVA) could divert an existing Th2 response and influence airway eosinophilia. The effects of BPP-OVA on airway inflammation were assessed in a classic murine sensitization/challenge model and an adoptive transfer model, which involved the adoptive transfer of in vitro differentiated ovalbumin (OVA)-specific Th2 cells. Functional T-cell stimulation by lung dendritic cells (DCs) was determined both in vitro and in vivo, combined with a cytokine secretion analysis. A single mucosal application of BPP-OVA efficiently delivered antigen, led to TLR2-mediated DC activation, and resulted in OVA-specific T-cell proliferation via lung DCs in vivo. In alternative models of allergic airway disease, a single administration of BPP-OVA before OVA challenge (but not BPP alone) significantly reduced airway eosinophilia, most likely through altered antigen-specific T-cell stimulation via DCs. Analyses of adoptively transferred Th2-biased cells after BPP-OVA administration in vivo suggested that BPP-OVA guides antigen-specific Th2 cells to produce significantly higher amounts of IFN-γ upon allergen challenge. In conclusion, our data show for the first time that a single mucosal administration of a TLR 2/6 agonist-allergen conjugate can provoke IFN-γ responses in Th2-biased cells and alleviate allergic airway inflammation.

Confirmation of a new conserved linear epitope of Lyssavirus nucleoprotein.

Science.gov (United States)

Xinjun, Lv; Xuejun, Ma; Lihua, Wang; Hao, Li; Xinxin, Shen; Pengcheng, Yu; Qing, Tang; Guodong, Liang

2012-05-01

Bioinformatics analysis was used to predict potential epitopes of Lyssavirus nucleoprotein and highlighted some distinct differences in the quantity and localization of the epitopes disclosed by epitope analysis of monoclonal antibodies against Lyssavirus nucleoprotein. Bioinformatics analysis showed that the domain containing residues 152-164 of Lyssavirus nucleoprotein was a conserved linear epitope that had not been reported previously. Immunization of two rabbits with the corresponding synthetic peptide conjugated to the Keyhole Limpe hemocyanin (KLH) macromolecule resulted in a titer of anti-peptide antibody above 1:200,000 in rabbit sera as detected by indirect enzyme-linked immunosorbent assay (ELISA). Western blot analysis demonstrated that the anti-peptide antibody recognized denatured Lyssavirus nucleoprotein in sodium dodecylsulfonate-polyacrylate gel electrophoresis (SDS-PAGE). Affinity chromatography purification and FITC-labeling of the anti-peptide antibody in rabbit sera was performed. FITC-labeled anti-peptide antibody could recognize Lyssavirus nucleoprotein in BSR cells and canine brain tissues even at a 1:200 dilution. Residues 152-164 of Lyssavirus nucleoprotein were verified as a conserved linear epitope in Lyssavirus. Copyright © 2012 Elsevier B.V. All rights reserved.

Are beta2-agonists responsible for increased mortality in heart failure?

LENUS (Irish Health Repository)

Bermingham, Margaret

2012-02-01

AIMS: Previous large-scale, retrospective studies have shown increased mortality in heart failure (HF) patients using beta2-agonists (B2As). We further examined the relationship between B2A use and mortality in a well-characterized population by adjusting for natriuretic peptide levels as a measure of HF severity. METHODS AND RESULTS: This was a retrospective cohort study of patients attending an HF Disease Management Programme with mean follow-up of 2.9 +\\/- 2.4 years. Chart review confirmed B2A use, dose and duration of use, and documented pulmonary function evaluation. The primary endpoint was the effect of B2A use compared with no B2A use on mortality using unadjusted and adjusted Kaplan-Meier survival curves. Data were available for 1294 patients (age 70.6 +\\/- 11.5 years) of whom 64% were male and 22.2% were taking B2As. beta2-Agonist users were older, more likely to be male, to have smoked, to have chronic obstructive pulmonary disease (COPD) and asthma, and less likely to take beta-blockers. Multivariable associates of mortality included: B-type natriuretic peptide (BNP), coronary artery disease, age, and beta-blocker use. Unadjusted mortality rates for B2A users were found to be significantly higher than non-B2A users [hazard ratio (HR) 1.304, 95% confidence interval (CI) 1.030-1.652, P= 0.028]. However, when adjusted for age, sex, medication, co-morbidity, smoking, COPD, and BNP differences, overall mortality rates were similar [HR 1.043, 95% CI (0.771-1.412), P= 0.783]. CONCLUSION: Unlike previous reports, this retrospective evaluation of B2A therapy in HF patients shows no relationship with long-term mortality when adjusted for population differences including BNP. Large, prospective studies are required to define the risk\\/benefit ratio of B2As in patients with heart failure.

A Tetrameric Peptide Derived from Bovine Lactoferricin Exhibits Specific Cytotoxic Effects against Oral Squamous-Cell Carcinoma Cell Lines

Directory of Open Access Journals (Sweden)

Víctor A. Solarte

2015-01-01

Full Text Available Several short linear peptides derived from cyclic bovine lactoferricin were synthesized and tested for their cytotoxic effect against the oral cavity squamous-cell carcinoma (OSCC cell lines CAL27 and SCC15. As a control, an immortalized and nontumorigenic cell line, Het-1A, was used. Linear peptides based on the RRWQWR core sequence showed a moderate cytotoxic effect and specificity towards tumorigenic cells. A tetrameric peptide, LfcinB(20–254, containing the RRWQWR motif, exhibited greater cytotoxic activity (>90% in both OSCC cell lines compared to the linear lactoferricin peptide or the lactoferrin protein. Additionally, this tetrameric peptide showed the highest specificity towards tumorigenic cells among the tested peptides. Interestingly, this effect was very fast, with cell shrinkage, severe damage to cell membrane permeability, and lysis within one hour of treatment. Our results are consistent with a necrotic effect rather than an apoptotic one and suggest that this tetrameric peptide could be considered as a new candidate for the therapeutic treatment of OSCC.

Antimicrobial Peptides from Plants

Directory of Open Access Journals (Sweden)

James P. Tam

2015-11-01

Full Text Available Plant antimicrobial peptides (AMPs have evolved differently from AMPs from other life forms. They are generally rich in cysteine residues which form multiple disulfides. In turn, the disulfides cross-braced plant AMPs as cystine-rich peptides to confer them with extraordinary high chemical, thermal and proteolytic stability. The cystine-rich or commonly known as cysteine-rich peptides (CRPs of plant AMPs are classified into families based on their sequence similarity, cysteine motifs that determine their distinctive disulfide bond patterns and tertiary structure fold. Cystine-rich plant AMP families include thionins, defensins, hevein-like peptides, knottin-type peptides (linear and cyclic, lipid transfer proteins, α-hairpinin and snakins family. In addition, there are AMPs which are rich in other amino acids. The ability of plant AMPs to organize into specific families with conserved structural folds that enable sequence variation of non-Cys residues encased in the same scaffold within a particular family to play multiple functions. Furthermore, the ability of plant AMPs to tolerate hypervariable sequences using a conserved scaffold provides diversity to recognize different targets by varying the sequence of the non-cysteine residues. These properties bode well for developing plant AMPs as potential therapeutics and for protection of crops through transgenic methods. This review provides an overview of the major families of plant AMPs, including their structures, functions, and putative mechanisms.

Short peptides allowing preferential detection of Candida albicans hyphae.

Science.gov (United States)

Kaba, Hani E J; Pölderl, Antonia; Bilitewski, Ursula

2015-09-01

Whereas the detection of pathogens via recognition of surface structures by specific antibodies and various types of antibody mimics is frequently described, the applicability of short linear peptides as sensor molecules or diagnostic tools is less well-known. We selected peptides which were previously reported to bind to recombinant S. cerevisiae cells, expressing members of the C. albicans Agglutinin-Like-Sequence (ALS) cell wall protein family. We slightly modified amino acid sequences to evaluate peptide sequence properties influencing binding to C. albicans cells. Among the selected peptides, decamer peptides with an "AP"-N-terminus were superior to shorter peptides. The new decamer peptide FBP4 stained viable C. albicans cells more efficiently in their mature hyphal form than in their yeast form. Moreover, it allowed distinction of C. albicans from other related Candida spp. and could thus be the basis for the development of a useful tool for the diagnosis of invasive candidiasis.

Peptide chemistry toolbox - Transforming natural peptides into peptide therapeutics.

Science.gov (United States)

Erak, Miloš; Bellmann-Sickert, Kathrin; Els-Heindl, Sylvia; Beck-Sickinger, Annette G

2018-06-01

The development of solid phase peptide synthesis has released tremendous opportunities for using synthetic peptides in medicinal applications. In the last decades, peptide therapeutics became an emerging market in pharmaceutical industry. The need for synthetic strategies in order to improve peptidic properties, such as longer half-life, higher bioavailability, increased potency and efficiency is accordingly rising. In this mini-review, we present a toolbox of modifications in peptide chemistry for overcoming the main drawbacks during the transition from natural peptides to peptide therapeutics. Modifications at the level of the peptide backbone, amino acid side chains and higher orders of structures are described. Furthermore, we are discussing the future of peptide therapeutics development and their impact on the pharmaceutical market. Copyright © 2018 Elsevier Ltd. All rights reserved.

Receptor binding properties and antinociceptive effects of chimeric peptides consisting of a micro-opioid receptor agonist and an ORL1 receptor antagonist.

Science.gov (United States)

Kawano, Susumu; Ito, Risa; Nishiyama, Miharu; Kubo, Mai; Matsushima, Tomoko; Minamisawa, Motoko; Ambo, Akihiro; Sasaki, Yusuke

2007-07-01

Receptor binding properties and antinociceptive activities of chimeric peptides linked by spacers were investigated. The peptides consisted of the micro-opioid receptor ligand dermorphin (Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH(2)) or its analog YRFB (Tyr-D-Arg-Phe-betaAla-NH(2)) linked to the ORL1 receptor ligand Ac-Arg-Tyr-Tyr-Arg-Ile-Lys-NH(2) (Ac-RYYRIK-NH(2)). All chimeric peptides were found to possess high receptor binding affinities for both micro-opioid and ORL1 receptors in mouse brain membranes although their binding affinities for both receptors in spinal membranes were significantly lower. Among them, chimeric peptide 2, which consists of dermorphin and Ac-RYYRIK-NH(2) connected by a long spacer, had the highest binding affinity towards both receptors. In the tail-flick test following intrathecal (i.t.) administration to mice, all chimeric peptides showed potent and dose-dependent antinociceptive activities with an ED(50) of 1.34-4.51 (pmol/mouse), nearly comparable to dermorphin alone (ED(50); 1.08 pmol/mouse). In contrast to their micro-opioid receptor binding profiles, intracerebroventricular (i.c.v.) administration of the chimeric peptides resulted in much less potent antinociceptive activity (ED(50) 5.55-100peptides, and the regulation of mu-opioid receptor-mediated antinociception in brain. The present chimeric peptides may be useful as pharmacological tools for studies on micro-opioid receptor/ORL1 receptor heterodimers.

Upregulation of α7 Nicotinic Receptors by Acetylcholinesterase C-Terminal Peptides

Science.gov (United States)

Bond, Cherie E.; Zimmermann, Martina; Greenfield, Susan A.

2009-01-01

Background The alpha-7 nicotinic acetylcholine receptor (α7-nAChR) is well known as a potent calcium ionophore that, in the brain, has been implicated in excitotoxicity and hence in the underlying mechanisms of neurodegenerative disorders such as Alzheimer's disease. Previous research implied that the activity of this receptor may be modified by exposure to a peptide fragment derived from the C-terminal region of the enzyme acetylcholinesterase. This investigation was undertaken to determine if the functional changes observed could be attributed to peptide binding interaction with the α7-nAChR, or peptide modulation of receptor expression. Methodology/Principal Findings This study provides evidence that two peptides derived from the C-terminus of acetylcholinesterase, not only selectively displace specific bungarotoxin binding at the α7-nAChR, but also alter receptor binding properties for its familiar ligands, including the alternative endogenous agonist choline. Of more long-term significance, these peptides also induce upregulation of α7-nAChR mRNA and protein expression, as well as enhancing receptor trafficking to the plasma membrane. Conclusions/Significance The results reported here demonstrate a hitherto unknown relationship between the α7-nAChR and the non-enzymatic functions of acetylcholinesterase, mediated independently by its C-terminal domain. Such an interaction may prove valuable as a pharmacological tool, prompting new approaches for understanding, and combating, the process of neurodegeneration. PMID:19287501

MIPs are ancestral ligands for the sex peptide receptor.

Science.gov (United States)

Kim, Young-Joon; Bartalska, Katarina; Audsley, Neil; Yamanaka, Naoki; Yapici, Nilay; Lee, Ju-Youn; Kim, Yong-Chul; Markovic, Milica; Isaac, Elwyn; Tanaka, Yoshiaki; Dickson, Barry J

2010-04-06

Upon mating, females of many animal species undergo dramatic changes in their behavior. In Drosophila melanogaster, postmating behaviors are triggered by sex peptide (SP), which is produced in the male seminal fluid and transferred to female during copulation. SP modulates female behaviors via sex peptide receptor (SPR) located in a small subset of internal sensory neurons that innervate the female uterus and project to the CNS. Although required for postmating responses only in these female sensory neurons, SPR is expressed broadly in the CNS of both sexes. Moreover, SPR is also encoded in the genomes of insects that lack obvious SP orthologs. These observations suggest that SPR may have additional ligands and functions. Here, we identify myoinhibitory peptides (MIPs) as a second family of SPR ligands that is conserved across a wide range of invertebrate species. MIPs are potent agonists for Drosophila, Aedes, and Aplysia SPRs in vitro, yet are unable to trigger postmating responses in vivo. In contrast to SP, MIPs are not produced in male reproductive organs, and are not required for postmating behaviors in Drosophila females. We conclude that MIPs are evolutionarily conserved ligands for SPR, which are likely to mediate functions other than the regulation of female reproductive behaviors.

G protein- and agonist-bound serotonin 5-HT2A receptor model activated by steered molecular dynamics simulations

DEFF Research Database (Denmark)

Ísberg, Vignir; Balle, Thomas; Sander, Tommy

2011-01-01

molecular dynamics (MD) simulations. The driving force for the transformation was the addition of several known intermolecular and receptor interhelical hydrogen bonds enforcing the necessary helical and rotameric movements. Subsquent MD simulations without constraints confirmed the stability......A 5-HT(2A) receptor model was constructed by homology modeling based on the ß(2)-adrenergic receptor and the G protein-bound opsin crystal structures. The 5-HT(2A) receptor model was transferred into an active conformation by an agonist ligand and a G(aq) peptide in four subsequent steered...

Simultaneous determination of β-agonists and monitoring in bovine tissues by liquid chromatography-tandem mass spectrometry

Directory of Open Access Journals (Sweden)

Kyunghun Jeong

2018-01-01

Full Text Available The misuse of β-agonists leads to a potential risk to public health and is forbidden in many countries. We developed a rapid, sensitive and reliable multi-residue detection method for zilpaterol, ractopamine, and clenbuterol in bovine tissues by liquid chromatography–tandem mass spectrometry. Residues were extracted in ethyl acetate after protein precipitation, and then analyzed by the developed method. Good linearities (R2 > 0.99 were observed, and the recoveries of zilpaterol, ractopamine, and clenbuterol were 99%, 74%, and 102%, respectively. The limits of quantitation for zilpaterol, ractopamine, and clenbuterol were 1.3, 5.0, and 1.7 ng/g, respectively. The method is also applied successfully to bovine tissues within the Korean National Residue Programme. None of the 3 β-agonists were detected from 50 domestic samples. However, zilpaterol (6.3 ng/g was quantified in one out of the 50 imported samples. The application of this method will be helpful in quality control analysis of β-agonists residues in bovine tissues.

Structural organization and spectroscopy of peptide-actinide(IV) complexes

International Nuclear Information System (INIS)

Dahou, S.

2010-01-01

The contamination of living organisms by actinide elements is at the origin of both radiological and chemical toxicity that may lead to severe dysfunction. Most of the data available on the actinide interaction with biological systems are macroscopic physiological measurements and are lacking a molecular description of the systems. Because of the intricacy of these systems, classical biochemical methods are difficult to implement. Our strategy consisted in designing simplified biomimetic peptides, and describing the corresponding intramolecular interactions with actinides. A carboxylic pentapeptide of the form DDPDD has been at the starting point of this work in order to further assess the influence of the peptide sequence on the topology of the complexes.To do so, various linear (Asp/Ala permutations, peptoids) and cyclic analogues have been synthesized. Furthermore, in order to include the hydroxamic function (with a high affinity for Fe(III)) in the peptide, both desferrioxamine and acetohydroxamic acid have been investigated. However because of difficulties in synthesis, we have not been able to test these peptides. Three actinide cations have been considered at oxidation state +IV (Th, Np, Pu) and compared to Fe(III), often considered as a biological surrogate of Pu(IV). The spatial arrangement of the peptide around the cation has been probed by spectrophotometry and X-ray Absorption Spectroscopy. The spectroscopic data and EXAFS data adjustment lead us to rationalize the topology of the complexes as a function of the peptide sequence: mix hydroxy polynuclear species for linear and cyclic peptides, mononuclear for the desferrioxamine complexes. Furthermore, significant differences have appeared between Fe(III) and actinide(IV), related to differences of reactivity in aqueous medium. (author)

Crystal structure of glucagon-like peptide-1 in complex with the extracellular domain of the glucagon-like peptide-1 receptor.

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Underwood, Christina Rye; Garibay, Patrick; Knudsen, Lotte Bjerre; Hastrup, Sven; Peters, Günther H; Rudolph, Rainer; Reedtz-Runge, Steffen

2010-01-01

GLP-1 (glucagon-like peptide-1) is an incretin released from intestinal L-cells in response to food intake. Activation of the GLP-1 receptor potentiates the synthesis and release of insulin from pancreatic beta-cells in a glucose-dependent manner. The GLP-1 receptor belongs to class B of the G-protein-coupled receptors, a subfamily characterized by a large N-terminal extracellular ligand binding domain. Exendin-4 and GLP-1 are 50% identical, and exendin-4 is a full agonist with similar affinity and potency for the GLP-1 receptor. We recently solved the crystal structure of the GLP-1 receptor extracellular domain in complex with the competitive antagonist exendin-4(9-39). Interestingly, the isolated extracellular domain binds exendin-4 with much higher affinity than the endogenous agonist GLP-1. Here, we have solved the crystal structure of the extracellular domain in complex with GLP-1 to 2.1 Aresolution. The structure shows that important hydrophobic ligand-receptor interactions are conserved in agonist- and antagonist-bound forms of the extracellular domain, but certain residues in the ligand-binding site adopt a GLP-1-specific conformation. GLP-1 is a kinked but continuous alpha-helix from Thr(13) to Val(33) when bound to the extracellular domain. We supplemented the crystal structure with site-directed mutagenesis to link the structural information of the isolated extracellular domain with the binding properties of the full-length receptor. The data support the existence of differences in the binding modes of GLP-1 and exendin-4 on the full-length GLP-1 receptor.

Dopaminergic agonists for hepatic encephalopathy

DEFF Research Database (Denmark)

Als-Nielsen, B; Gluud, L L; Gluud, C

2004-01-01

Hepatic encephalopathy may be associated with an impairment of the dopaminergic neurotransmission. Dopaminergic agonists may therefore have a beneficial effect on patients with hepatic encephalopathy.......Hepatic encephalopathy may be associated with an impairment of the dopaminergic neurotransmission. Dopaminergic agonists may therefore have a beneficial effect on patients with hepatic encephalopathy....

TRC210258, a novel TGR5 agonist, reduces glycemic and dyslipidemic cardiovascular risk in animal models of diabesity

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Zambad SP

2013-12-01

Full Text Available Shitalkumar P Zambad, Davinder Tuli, Anoop Mathur, Sameer A Ghalsasi, Anita R Chaudhary, Shailesh Deshpande, Ramesh C Gupta, Vijay Chauthaiwale, Chaitanya DuttTorrent Research Centre, Torrent Pharmaceuticals Ltd, Gujarat, IndiaBackground: Patients with diabesity have a significantly increased risk of developing cardiovascular disease. Therefore, therapy addressing the multiple metabolic abnormalities linked with diabesity and leading to further reduction of cardiovascular risk is highly desirable. Activation of the TGR5 receptor holds therapeutic potential for diabesity. In the present study, we evaluated the efficacy of TRC210258, a novel TGR5 agonist, in clinically relevant animal models of diabesity.Methods: A novel small molecule, TRC210258 (N-(4-chlorophenyl-2-(4-fluoro phenoxy-N-methylimidazo (1, 2-a pyrimidine-3-carboxamide, was synthesized. The in vitro TGR5 receptor activation potential of TRC210258 was assessed by cyclic adinosine monophosphate (cAMP assay and cAMP-responsive element reporter assay using cells overexpressing the human TGR5 receptor. The effect of TRC210258 on glucagon-like peptide-1 release was evaluated in vitro using a human enteroendocrine cell line. The effect of TRC210258 on energy expenditure and glycemic control was evaluated in high-fat diet-induced obese mice. Additionally, the effect of TRC210258 on dyslipidemic parameters was determined in high fat-fed hamsters.Results: TRC210258 demonstrated potent TGR5 agonist activity, with enhanced glucagon-like peptide-1 release and energy expenditure. Treatment with TRC210258 resulted in better glycemic control and improved parameters of dyslipidemia such as plasma triglyceride, low-density lipoprotein cholesterol, and non-high-density lipoprotein cholesterol levels. Treatment with TRC210258 also improved emerging dyslipidemic cardiovascular risk parameters, including remnant cholesterol and triglyceride clearance.Conclusion: This study highlights the potential of TRC

Beta-agonists and animal welfare

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The use of beta-agonists in animal feed is a high profile topic within the U.S. as consumers and activist groups continue to question its safety. The only beta-agonist currently available for use in swine is ractopamine hydrochloride (RAC). This is available as Paylean™ (Elanco Animal Health – FDA a...

Monitoring β-arrestin recruitment via β-lactamase enzyme fragment complementation: purification of peptide E as a low-affinity ligand for mammalian bombesin receptors.

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Yuichi Ikeda

Full Text Available Identification of cognate ligands for G protein-coupled receptors (GPCRs provides a starting point for understanding novel regulatory mechanisms. Although GPCR ligands have typically been evaluated through the activation of heterotrimeric G proteins, recent studies have shown that GPCRs signal not only through G proteins but also through β-arrestins. As such, monitoring β-arrestin signaling instead of G protein signaling will increase the likelihood of identifying currently unknown ligands, including β-arrestin-biased agonists. Here, we developed a cell-based assay for monitoring ligand-dependent GPCR-β-arrestin interaction via β-lactamase enzyme fragment complementation. Inter alia, β-lactamase is a superior reporter enzyme because of its cell-permeable fluorescent substrate. This substrate makes the assay non-destructive and compatible with fluorescence-activated cell sorting (FACS. In a reporter cell, complementary fragments of β-lactamase (α and ω were fused to β-arrestin 2 and GPCR, respectively. Ligand stimulation initiated the interaction of these chimeric proteins (β-arrestin-α and GPCR-ω, and this inducible interaction was measured through reconstituted β-lactamase activity. Utilizing this system, we screened various mammalian tissue extracts for agonistic activities on human bombesin receptor subtype 3 (hBRS3. We purified peptide E as a low-affinity ligand for hBRS3, which was also found to be an agonist for the other two mammalian bombesin receptors such as gastrin-releasing peptide receptor (GRPR and neuromedin B receptor (NMBR. Successful purification of peptide E has validated the robustness of this assay. We conclude that our newly developed system will facilitate the discovery of GPCR ligands.

An altered gp100 peptide ligand with decreased binding by TCR and CD8alpha dissects T cell cytotoxicity from production of cytokines and activation of NFAT

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Niels eSchaft

2013-09-01

Full Text Available Altered peptide ligands (APLs provide useful tools to study T cell activation and potentially direct immune responses to improve treatment of cancer patients. To better understand and exploit APLs, we studied the relationship between APLs and T cell function in more detail. Here, we tested a broad panel of gp100(280-288 APLs with respect to T cell cytotoxicity, production of cytokines and activation of Nuclear Factor of Activated T cells (NFAT by human T cells gene-engineered with a gp100-HLA-A2-specific TCRalpha/beta. We demonstrated that gp100-specific cytotoxicity, production of cytokines, and activation of NFAT were not affected by APLs with single amino acid substitutions, except for an APL with an amino acid substitution at position 3 (APL A3, which did not elicit any T cell response. A gp100 peptide with a double amino acid mutation (APL S4S6 elicited T cell cytotoxicity and production of IFNgamma, and to a lesser extent TNFalpha, IL-4, and IL-5, but not production of IL-2 and IL-10, or activation of NFAT. Notably, TCR-mediated functions showed decreases in sensitivities for S4S6 versus gp100 wt peptide, which were minor for cytotoxicity but at least a 1000-fold more prominent for the production of cytokines. TCR-engineered T cells did not bind A3-HLA-A2, but did bind S4S6-HLA-A2 although to a lowered extent compared to wt peptide-HLA-A2. Moreover, S4S6-induced T cell function demonstrated an enhanced dependency on CD8alpha. Taken together, most gp100 APLs functioned as agonists, but A3 and S4S6 peptides acted as a null ligand and partial agonist, respectively. Our results further suggest that TCR-mediated cytotoxicity can be dissected from production of cytokines and activation of NFAT, and that the agonist potential of peptide mutants relates to the extent of binding by TCR and CD8alpha. These findings may facilitate the design of APLs to advance the study of T cell activation and their use for therapeutic applications.

Role and development of GLP-1 receptor agonists in the management of diabetes

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Chee W Chia

2009-05-01

Full Text Available Chee W Chia, Josephine M EganNational Institutes of Health, National Institute on Aging, Intramural Research Program, Baltimore, Maryland, USAAbstract: Glucagon-like peptide-1 (GLP-1 is a hormone secreted from enteroendocrine L cells of the intestine in response to food. Exogenous GLP-1 administration at pharmacological doses results in many effects that are beneficial for treating type 2 diabetes, these include: (1 an increase in insulin secretion from β cells; (2 a suppression of glucagon secretion from α cells in the presence of hyperglycemia but not hypoglycemia; (3 a delay in gastric emptying and gut motility which in turns delays absorption of ingested nutrients and dampens post-prandial glucose excursion; and (4 an increase in the duration of postprandial satiety therefore suppressing appetite and decreasing food intake which eventually leads to weight loss. However, GLP-1 is subject to rapid enzymatic degradation, and therefore, not suitable for long-term treatment. A synthetic enzyme-resistant GLP-1 receptor agonist that reproduces the biological effects of GLP-1 is in use and more are under development. This review aims at providing a summary of the properties of GLP-1 and the development of GLP-1-based therapies for treatment of diabetes.Keywords: incretin, GLP-1, GLP-1R agonist, diabetes

Chimeric relaxin peptides highlight the role of the A-chain in the function of H2 relaxin.

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Hossain, Mohammed Akhter; Wade, John D; Bathgate, Ross A D

2012-05-01

Human gene-2 (H2) relaxin is a member of the insulin-relaxin peptide superfamily. Because of the potential clinical applications of H2 relaxin, there is a need for novel analogs that have improved biological activity and receptor specificity. In this respect, we have chemically assembled chimeric peptides consisting of the B-chain of H2 relaxin in combination with A-chains from other insulin/relaxin family members. The peptides were prepared using solid phase peptide synthesis together with regioselective disulfide bond formation and characterized by RP-HPLC, MALDI-TOF MS and amino acid analysis. Their in vitro activity was assessed in RXFP1 or RXFP2 expressing cells. Replacement of the H2 relaxin A-chain resulted in parallel losses of binding affinity and activity on RXFP1. Not surprisingly H1A-H2B demonstrated the highest activity as the H1 A-chain shares high homology with H2 relaxin whereas INSLA-H2B, which shows low homology, had very poor activity. Importantly A-chain replacements had a dramatic effect on RXFP2 activity similar to previous results demonstrating different modes of activation of A-chain variants on RXFP1 and RXFP2. H3A-H2B is particularly interesting as it displays moderate activity at RXFP1 but poor activity at RXFP2 indicating that it may be a template for specific RXFP1 agonist development. Our study confirms that the activity of H2 relaxin at both RXFP1 and RXFP2 relies on interactions with both the B- and A-chains, and also provide new biochemical insights into the mechanism of relaxin action that the A-chain needs to be in native or near-native form for strong RXFP1 or RXFP2 agonist activity. Copyright © 2012 Elsevier Inc. All rights reserved.

[BIOLOGICAL ACTIVITY OF ANTIMICROBIAL PEPTIDES FROM CHICKENS THROMBOCYTES].

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Sycheva, M V; Vasilchenko, A S; Rogozhin, E A; Pashkova, T M; Popova, L P; Kartashova, O L

2016-01-01

Isolation and study of biological activity of antimicrobial peptides from chickens thrombocytes. Peptides from chickens thrombocytes, obtained by reverse-phase high-performance liquid chromatography method with stepped and linear gradients of concentration increase of the organic solvent were used in the study. Their antimicrobial activity was determined by microtitration method in broth; mechanism of biological effect--by using fluorescent spectroscopy method with DNA-tropic dyes. Individual fractions of peptides were isolated from chickens thrombocytes, that possess antimicrobial activity against Staphylococcus aureus P209 and Escherichia coli K12. A disruption of integrity of barrier structures of microorganisms under the effect of thrombocyte antimicrobial peptides and predominance of cells with damaged membrane in the population of E. coli was established. The data obtained on antimicrobial activity and mechanism of bactericidal effect of the peptide fractions from chickens thrombocytes isolated for the first time expand the understanding of functional properties of chickens thrombocytes and open a perspective for their further study with the aim of use as antimicrobial means.

Improved proteolytic stability and potent activity against Leishmania infantum trypanothione reductase of α/β-peptide foldamers conjugated to cell-penetrating peptides.

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de Lucio, Héctor; Gamo, Ana María; Ruiz-Santaquiteria, Marta; de Castro, Sonia; Sánchez-Murcia, Pedro A; Toro, Miguel A; Gutiérrez, Kilian Jesús; Gago, Federico; Jiménez-Ruiz, Antonio; Camarasa, María-José; Velázquez, Sonsoles

2017-11-10

The objective of the current study was to enhance the proteolytic stability of peptide-based inhibitors that target critical protein-protein interactions at the dimerization interface of Leishmania infantum trypanothione reductase (Li-TryR) using a backbone modification strategy. To achieve this goal we carried out the synthesis, proteolytic stability studies and biological evaluation of a small library of α/β 3 -peptide foldamers of different length (from 9-mers to 13-mers) and different α→β substitution patterns related to prototype linear α-peptides. We show that several 13-residue α/β 3 -peptide foldamers retain inhibitory potency against the enzyme (in both activity and dimerization assays) while they are far less susceptible to proteolytic degradation than an analogous α-peptide. The strong dependence of the binding affinities for Li-TryR on the length of the α,β-peptides is supported by theoretical calculations on conformational ensembles of the resulting complexes. The conjugation of the most proteolytically stable α/β-peptide with oligoarginines results in a molecule with potent activity against L. infantum promastigotes and amastigotes. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

A linear programming model for protein inference problem in shotgun proteomics.

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Huang, Ting; He, Zengyou

2012-11-15

Assembling peptides identified from tandem mass spectra into a list of proteins, referred to as protein inference, is an important issue in shotgun proteomics. The objective of protein inference is to find a subset of proteins that are truly present in the sample. Although many methods have been proposed for protein inference, several issues such as peptide degeneracy still remain unsolved. In this article, we present a linear programming model for protein inference. In this model, we use a transformation of the joint probability that each peptide/protein pair is present in the sample as the variable. Then, both the peptide probability and protein probability can be expressed as a formula in terms of the linear combination of these variables. Based on this simple fact, the protein inference problem is formulated as an optimization problem: minimize the number of proteins with non-zero probabilities under the constraint that the difference between the calculated peptide probability and the peptide probability generated from peptide identification algorithms should be less than some threshold. This model addresses the peptide degeneracy issue by forcing some joint probability variables involving degenerate peptides to be zero in a rigorous manner. The corresponding inference algorithm is named as ProteinLP. We test the performance of ProteinLP on six datasets. Experimental results show that our method is competitive with the state-of-the-art protein inference algorithms. The source code of our algorithm is available at: https://sourceforge.net/projects/prolp/. zyhe@dlut.edu.cn. Supplementary data are available at Bioinformatics Online.

Improving serodiagnosis of human and canine leishmaniasis with recombinant Leishmania braziliensis cathepsin l-like protein and a synthetic peptide containing its linear B-cell epitope.

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Daniel Menezes-Souza

2015-01-01

Full Text Available The early and correct diagnosis of human leishmaniasis is essential for disease treatment. Another important step in the control of visceral leishmaniasis is the identification of infected dogs, which are the main domestic reservoir of L. infantum. Recombinant proteins and synthetic peptides based on Leishmania genes have emerged as valuable targets for serodiagnosis due to their increased sensitivity, specificity and potential for standardization. Cathepsin L-like genes are surface antigens that are secreted by amastigotes and have little similarity to host proteins, factors that enable this protein as a good target for serodiagnosis of the leishmaniasis.We mapped a linear B-cell epitope within the Cathepsin L-like protein from L. braziliensis. A synthetic peptide containing the epitope and the recombinant protein was evaluated for serodiagnosis of human tegumentary and visceral leishmaniasis, as well as canine visceral leishmaniasis.The recombinant protein performed best for human tegumentary and canine visceral leishmaniasis, with 96.30% and 89.33% accuracy, respectively. The synthetic peptide was the best to discriminate human visceral leishmaniasis, with 97.14% specificity, 94.55% sensitivity and 96.00% accuracy. Comparison with T. cruzi-infected humans and dogs suggests that the identified epitope is specific to Leishmania parasites, which minimizes the likelihood of cross-reactions.

Acute effects of the glucagon-like peptide-1 receptor agonist, exenatide, on blood pressure and heart rate responses to intraduodenal glucose infusion in type 2 diabetes.

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Thazhath, Sony S; Marathe, Chinmay S; Wu, Tongzhi; Chang, Jessica; Khoo, Joan; Kuo, Paul; Checklin, Helen L; Bound, Michelle J; Rigda, Rachael S; Horowitz, Michael; Jones, Karen L; Rayner, Christopher K

2017-01-01

To evaluate the effects of the glucagon-like peptide-1 receptor agonist, exenatide, on blood pressure and heart rate during an intraduodenal glucose infusion in type 2 diabetes. Nine subjects with type 2 diabetes were randomised to receive intravenous exenatide or saline control in a crossover design. Glucose (3 kcal min -1 ) was infused via an intraduodenal manometry catheter for 60 min. Blood pressure, heart rate, and the frequency and amplitude of duodenal pressure waves were measured at regular intervals. Gastrointestinal symptoms were monitored using 100 mm visual analogue scales. During intraduodenal glucose infusion (0-60 min), diastolic (p (0-60)  = 0.03) and mean arterial (p (0-60)  = 0.03) blood pressures and heart rate (p (0-60)  = 0.06; p (0-120)  = 0.03)) were higher with exenatide compared to placebo. The increase in the area under the curve for diastolic blood pressure and mean arterial blood pressure was related directly to the suppression of the duodenal motility index with exenatide compared to control (p = 0.007 and 0.04, respectively). In type 2 diabetes, intravenous exenatide increases mean arterial blood pressure and heart rate during an intraduodenal glucose infusion, supporting the need for further research with exenatide for its potential use in postprandial hypotension. © The Author(s) 2016.

Modification of kindled amygdaloid seizures by opiate agonists and antagonists.

Science.gov (United States)

Albertson, T E; Joy, R M; Stark, L G

1984-03-01

The effects of 19 opiate agonists and antagonists on kindled amygdaloid seizures in the rat were studied. The mu agonists tended to reduce the length of elicited afterdischarges and behavioral ranks, while markedly increasing postictal electroencephalogram spikes and behavioral arrest time. These effects were reversed by naloxone. The kappa agonists reduced behavioral rank and variably reduced afterdischarge length with a concomitant lengthening of postictal behavioral arrest time and number of electroencephalogram spikes. The putative sigma agonist, SKF 10,047, reduced afterdischarge durations only at the higher doses tested. The decreases found after the sigma agonists in postictal electroencephalogram spiking and time of behavioral arrest were not reversed by naloxone. Only the lower doses of normeperidine were found to decrease seizure thresholds. The mixed agonist/antagonists (MAA) cyclazocine and cyclorphan markedly increased seizure threshold and reduced afterdischarge duration and behavioral rank. Only the MAA pentazocine tended to increase threshold but not suprathreshold afterdischarge durations. The order of ability to modify the ictal events was MAA (selected) greater than kappa agonists greater than mu agonists greater than sigma agonists. The increase in postictal events (behavior arrest and spikes) was caused most effectively by pretreatment with mu agonist greater than kappa agonist greater than selected MAA greater than sigma agonists.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibacterial Synthetic Peptides Derived from Bovine Lactoferricin Exhibit Cytotoxic Effect against MDA-MB-468 and MDA-MB-231 Breast Cancer Cell Lines

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Yerly Vargas Casanova

2017-09-01

Full Text Available Linear, dimeric, tetrameric, and cyclic peptides derived from lactoferricin B, containing the RRWQWR motif, were designed, synthesized, purified, and characterized using RP-HPLC chromatography and MALDI-TOF mass spectrometry. The antibacterial activity of the designed peptides against E. coli (ATCC 11775 and 25922 and their cytotoxic effect against MDA-MB-468 and MDA-MB-231 breast cancer cell lines were evaluated. Dimeric and tetrameric peptides showed higher antibacterial activity in both bacteria strains than linear peptides. The dimeric peptide (RRWQWR2K-Ahx exhibited the highest antibacterial activity against the tested bacterial strains. Furthermore, the peptides with high antibacterial activity exhibited significant cytotoxic effect against the tested breast cancer cell lines. This cytotoxic effect was fast and dependent on the peptide concentration. The tetrameric molecule containing RRWQWR motif has an optimal cytotoxic effect at a concentration of 22 µM. The evaluated dimeric and tetrameric peptides could be considered as candidates for developing new therapeutic agents against breast cancer. Polyvalence of linear sequences could be considered as a novel and versatile strategy for obtaining molecules with high anticancer activity.

Antibacterial Synthetic Peptides Derived from Bovine Lactoferricin Exhibit Cytotoxic Effect against MDA-MB-468 and MDA-MB-231 Breast Cancer Cell Lines.

Science.gov (United States)

Vargas Casanova, Yerly; Rodríguez Guerra, Jorge Antonio; Umaña Pérez, Yadi Adriana; Leal Castro, Aura Lucía; Almanzar Reina, Giovanni; García Castañeda, Javier Eduardo; Rivera Monroy, Zuly Jenny

2017-09-29

Linear, dimeric, tetrameric, and cyclic peptides derived from lactoferricin B, containing the RRWQWR motif, were designed, synthesized, purified, and characterized using RP-HPLC chromatography and MALDI-TOF mass spectrometry. The antibacterial activity of the designed peptides against E. coli (ATCC 11775 and 25922) and their cytotoxic effect against MDA-MB-468 and MDA-MB-231 breast cancer cell lines were evaluated. Dimeric and tetrameric peptides showed higher antibacterial activity in both bacteria strains than linear peptides. The dimeric peptide (RRWQWR)₂K-Ahx exhibited the highest antibacterial activity against the tested bacterial strains. Furthermore, the peptides with high antibacterial activity exhibited significant cytotoxic effect against the tested breast cancer cell lines. This cytotoxic effect was fast and dependent on the peptide concentration. The tetrameric molecule containing RRWQWR motif has an optimal cytotoxic effect at a concentration of 22 µM. The evaluated dimeric and tetrameric peptides could be considered as candidates for developing new therapeutic agents against breast cancer. Polyvalence of linear sequences could be considered as a novel and versatile strategy for obtaining molecules with high anticancer activity.

Antimicrobial peptides: the role of hydrophobicity in the alpha helical structure

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Pandurangan Perumal

2013-12-01

Full Text Available The antimicrobial peptides (AMPs are a class of molecule obtained from plants, insects, animals, and humans. These peptides have been classified into five categories: 1. Anionic peptide, 2. Linear alpha helical cationic peptide, 3. Cationic peptide, 4. Anionic and cationic peptides with disulphide bonds, and 5. Anionic and cationic peptide fragments of larger proteins. Factors affecting AMPs are sequence, size, charge, hydrophobicity, amphipathicity, structure and conformation. Synthesis of these peptides is convenient by using solid phase peptide synthesis by using FMOC chemistry protocol. The secondary structures of three synthetic peptides were determined by circular dichroism. Also, it was compared the stability of the α-helical structure and confirmed the percentage of helix of these peptides by using circular dichroism. Some of these AMPs show therapeutic properties like antimicrobial, antiviral, contraceptive, and anticancer. The formulations of some peptides have been entered into the phase I, II, or III of clinical trials. This article to review briefly the sources, classification, factors affecting AMPs activity, synthesis, characterization, mechanism of action and therapeutic concern of AMPs and mainly focussed on percentage of α-helical structure in various medium.

Radio-peptides targeting g-protein coupled receptors in cancer: from bench to bed

International Nuclear Information System (INIS)

Maecke, H.R.

2015-01-01

be discussed. They appear to have better imaging properties than agonists. How (coordination) chemistry affects pharmacology will be an important focus of this lecture. Another important aspect will be to discuss the different properties of agonistic radioligands which cause signaling and internalisation (transfer of the receptor ligand complex into the cell) and antagonists which block the action of agonists and are not internalised but may recognise more receptor binding sites. Finally early and extended human use studies will be presented for the 2 tumor entities mentioned above. It will be demonstrated how improved peptide and chelate chemistry improves diagnostic accuracy and therapeutic outcome in tumor treatment. (author)

Chimeric vaccine composed of viral peptide and mammalian heat-shock protein 60 peptide protects against West Nile virus challenge.

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Gershoni-Yahalom, Orly; Landes, Shimon; Kleiman-Shoval, Smadar; Ben-Nathan, David; Kam, Michal; Lachmi, Bat-El; Khinich, Yevgeny; Simanov, Michael; Samina, Itzhak; Eitan, Anat; Cohen, Irun R; Rager-Zisman, Bracha; Porgador, Angel

2010-08-01

The protective efficacy and immunogenicity of a chimeric peptide against West Nile virus (WNV) was evaluated. This virus is the aetiological agent of West Nile fever, which has recently emerged in the western hemisphere. The rapid spread of WNV throughout North America, as well as the constantly changing epidemiology and transmission of the virus by blood transfusion and transplantation, have raised major public-health concerns. Currently, there are no effective treatments for WNV or vaccine for human use. We previously identified a novel, continuous B-cell epitope from domain III of the WNV envelope protein, termed Ep15. To test whether this epitope can protect against WNV infection, we synthesized a linear chimeric peptide composed of Ep15 and the heat-shock protein 60 peptide, p458. The p458 peptide is an effective carrier peptide for subunit vaccines against other infectious agents. We now report that mice immunized with the chimeric peptide, p458-Ep15, were resistant to lethal challenges with three different WNV strains. Moreover, their brains were free of viral genome and infectious virus. Mice immunized with Ep15 alone or with p431-Ep15, a control conjugate, were not protected. The chimeric p458-Ep15 peptide induced WNV-specific immunoglobulin G antibodies that neutralized the virus and induced the secretion of interferon-gammain vitro. Challenge of chimeric peptide-immunized mice considerably enhanced WNV-specific neutralizing antibodies. We conclude that this chimeric peptide can be used for formulation of a human vaccine against WNV.

Immobilisation of linear and cyclic RGD-peptides on titanium surfaces and their impact on endothelial cell adhesion and proliferation

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PW Kämmerer

2011-04-01

Full Text Available Functional coatings on titanium vascular stents and endosseous dental implants could probably enhance endothelial cell (EC adhesion and activity with a shortening of the wound healing time and an increase of peri-implant angiogenesis during early bone formation. Therefore, the role of the structure of linear and cyclic cell adhesive peptides Arg-Gly-Asp (l-RGD and c-RGD on differently pre-treated titanium (Ti surfaces (untreated, silanised vs. functionalised with l- and c-RGD peptides on EC cell coverage and proliferation was evaluated. After 24 h and after 3 d, surface coverage of adherent cells was quantified and an alamarBlue® proliferation assay was conducted. After 24 h, l-RGD modified surfaces showed a significantly better coverage of adhered cells than untreated titanium (p=0.01. Differences between l-RGD surfaces and silanised Ti (p=0.066 as well as between l-RGD and c-RGD surfaces (p=0.191 were not significant. After 3 d, c-RGD surfaces showed a significantly higher cell coverage than untreated Ti, silanised and l-RGD titanium surfaces (all p<0.0001. After 24 h, c-RGD modified surfaces showed significant higher cell proliferation compared to untreated Ti (p=0.003. However, there were no differences in proliferation between c-RGD and l-RGD (p=0.126 or c-RGD and silanised titanium (p=0.196. After 3 d, proliferation on c-RGD surfaces outranged significantly untreated titanium (p=0.004, silanised (p=0.001 and l-RGD surfaces (p=0.023, whereas no significant difference could be found between untreated Ti and l-RGD surfaces (p=0.54. According to these results, the biomimetic coating of c-RGD peptides on conventional titanium surfaces showed a positive effect on EC cell coverage and proliferation. We were able to show that modifications of titanium surfaces with c-RGD are a promising approach in promoting endothelial cell growth.

Crystal Structure of Glucagon-like Peptide-1 in Complex with the Extracellular Domain of the Glucagon-like Peptide-1 Receptor*

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Underwood, Christina Rye; Garibay, Patrick; Knudsen, Lotte Bjerre; Hastrup, Sven; Peters, Günther H.; Rudolph, Rainer; Reedtz-Runge, Steffen

2010-01-01

GLP-1 (glucagon-like peptide-1) is an incretin released from intestinal L-cells in response to food intake. Activation of the GLP-1 receptor potentiates the synthesis and release of insulin from pancreatic β-cells in a glucose-dependent manner. The GLP-1 receptor belongs to class B of the G-protein-coupled receptors, a subfamily characterized by a large N-terminal extracellular ligand binding domain. Exendin-4 and GLP-1 are 50% identical, and exendin-4 is a full agonist with similar affinity and potency for the GLP-1 receptor. We recently solved the crystal structure of the GLP-1 receptor extracellular domain in complex with the competitive antagonist exendin-4(9–39). Interestingly, the isolated extracellular domain binds exendin-4 with much higher affinity than the endogenous agonist GLP-1. Here, we have solved the crystal structure of the extracellular domain in complex with GLP-1 to 2.1 Åresolution. The structure shows that important hydrophobic ligand-receptor interactions are conserved in agonist- and antagonist-bound forms of the extracellular domain, but certain residues in the ligand-binding site adopt a GLP-1-specific conformation. GLP-1 is a kinked but continuous α-helix from Thr13 to Val33 when bound to the extracellular domain. We supplemented the crystal structure with site-directed mutagenesis to link the structural information of the isolated extracellular domain with the binding properties of the full-length receptor. The data support the existence of differences in the binding modes of GLP-1 and exendin-4 on the full-length GLP-1 receptor. PMID:19861722

Dopamine agonist withdrawal syndrome: implications for patient care.

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Nirenberg, Melissa J

2013-08-01

Dopamine agonists are effective treatments for a variety of indications, including Parkinson's disease and restless legs syndrome, but may have serious side effects, such as orthostatic hypotension, hallucinations, and impulse control disorders (including pathological gambling, compulsive eating, compulsive shopping/buying, and hypersexuality). The most effective way to alleviate these side effects is to taper or discontinue dopamine agonist therapy. A subset of patients who taper a dopamine agonist, however, develop dopamine agonist withdrawal syndrome (DAWS), which has been defined as a severe, stereotyped cluster of physical and psychological symptoms that correlate with dopamine agonist withdrawal in a dose-dependent manner, cause clinically significant distress or social/occupational dysfunction, are refractory to levodopa and other dopaminergic medications, and cannot be accounted for by other clinical factors. The symptoms of DAWS include anxiety, panic attacks, dysphoria, depression, agitation, irritability, suicidal ideation, fatigue, orthostatic hypotension, nausea, vomiting, diaphoresis, generalized pain, and drug cravings. The severity and prognosis of DAWS is highly variable. While some patients have transient symptoms and make a full recovery, others have a protracted withdrawal syndrome lasting for months to years, and therefore may be unwilling or unable to discontinue DA therapy. Impulse control disorders appear to be a major risk factor for DAWS, and are present in virtually all affected patients. Thus, patients who are unable to discontinue dopamine agonist therapy may experience chronic impulse control disorders. At the current time, there are no known effective treatments for DAWS. For this reason, providers are urged to use dopamine agonists judiciously, warn patients about the risks of DAWS prior to the initiation of dopamine agonist therapy, and follow patients closely for withdrawal symptoms during dopamine agonist taper.

Development of betulinic acid as an agonist of TGR5 receptor using a new in vitro assay

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Lo SH

2016-08-01

Full Text Available Shih-Hsiang Lo,1,2 Kai-Chung Cheng,3 Ying-Xiao Li,3,4 Chin-Hong Chang,4,5 Juei-Tang Cheng,4,6 Kung-Shing Lee7,8 1Division of Cardiology, Department of Internal Medicine, Zhongxing Branch of Taipei City Hospital, 2Department of History and Geography, University of Taipei, Taipei, Taiwan; 3Department of Psychosomatic Internal Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan; 4Department of Medical Research, 5Department of Neurosurgery, Chi-Mei Medical Center, Yong Kang, 6Institute of Medical Science, College of Health Science, Chang Jung Christian University, Tainan, 7Department of Surgery, Pingtung Hospital, 8Division of Neurosurgery, Department of Surgery, Kaohsiung Medical University Chung-Ho Memorial Hospital, School of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan Background: G-protein-coupled bile acid receptor 1, also known as TGR5 is known to be involved in glucose homeostasis. In animal models, treatment with a TGR5 agonist induces incretin secretion to reduce hyperglycemia. Betulinic acid, a triterpenoid present in the leaves of white birch, has been introduced as a selective TGR5 agonist. However, direct activation of TGR5 by betulinic acid has not yet been reported. Methods: Transfection of TGR5 into cultured Chinese hamster ovary (CHO-K1 cells was performed to establish the presence of TGR5. Additionally, TGR5-specific small interfering RNA was employed to silence TGR5 in cells (NCI-H716 cells that secreted incretins. Uptake of glucose by CHO-K1 cells was evaluated using a fluorescent indicator. Amounts of cyclic adenosine monophosphate and glucagon-like peptide were quantified using enzyme-linked immunosorbent assay kits. Results: Betulinic acid dose-dependently increases glucose uptake by CHO-K1 cells transfected with TGR5 only, which can be considered an alternative method instead of radioligand binding assay. Additionally, signals coupled to TGR5 activation are also

New benzylureas as a novel series of potent, nonpeptidic vasopressin V2 receptor agonists.

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Yea, Christopher M; Allan, Christine E; Ashworth, Doreen M; Barnett, James; Baxter, Andy J; Broadbridge, Janice D; Franklin, Richard J; Hampton, Sally L; Hudson, Peter; Horton, John A; Jenkins, Paul D; Penson, Andy M; Pitt, Gary R W; Rivière, Pierre; Robson, Peter A; Rooker, David P; Semple, Graeme; Sheppard, Andy; Haigh, Robert M; Roe, Michael B

2008-12-25

Vasopressin (AVP) is a hormone that stimulates an increase in water permeability through activation of V2 receptors in the kidney. The analogue of AVP, desmopressin, has proven an effective drug for diseases where a reduction of urine output is desired. However, its peptidic nature limits its bioavailability. We report herein the discovery of potent, nonpeptidic, benzylurea derived agonists of the vasopressin V2 receptor. We describe substitutions on the benzyl group to give improvements in potency and subsequent modifications to the urea end group to provide improvements in solubility and increased oral efficacy in a rat model of diuresis. The lead compound 20e (VA106483) is reported for the first time and has been selected for clinical development.

Immunization of chickens with an agonistic monoclonal anti-chicken CD40 antibody-hapten complex: rapid and robust IgG response induced by a single subcutaneous injection.

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Chen, Chang-Hsin; Abi-Ghanem, Daad; Waghela, Suryakant D; Chou, Wen-Ko; Farnell, Morgan B; Mwangi, Waithaka; Berghman, Luc R

2012-04-30

Producing diagnostic antibodies in chicken egg yolk represents an alternate animal system that offers many advantages including high productivity at low cost. Despite being an excellent counterpart to mammalian antibodies, chicken IgG from yolk still represents an underused resource. The potential of agonistic monoclonal anti-CD40 antibodies (mAb) as a powerful immunological adjuvant has been demonstrated in mammals, but not in chickens. We recently reported an agonistic anti-chicken CD40 mAb (designated mAb 2C5) and showed that it may have potential as an immunological adjuvant. In this study, we examined the efficacy of targeting a short peptide to chicken CD40 [expressed by the antigen-presenting cells (APCs)] in enhancing an effective IgG response in chickens. For this purpose, an immune complex consisting of one streptavidin molecule, two directionally biotinylated mAb 2C5 molecules, and two biotinylated peptide molecules was produced. Chickens were immunized subcutaneously with doses of this complex ranging from 10 to 90 μg per injection once, and relative quantification of the peptide-specific IgG response showed that the mAb 2C5-based complex was able to elicit a strong IgG response as early as four days post-immunization. This demonstrates that CD40-targeting antigen to chicken APCs can significantly enhance antibody responses and induce immunoglobulin isotype-switching. This immunization strategy holds promise for rapid production of hapten-specific IgG in chickens. Copyright © 2012 Elsevier B.V. All rights reserved.

Ranakinestatin-PPF from the Skin Secretion of the Fukien Gold-Striped Pond Frog, Pelophylax plancyi fukienensis: A Prototype of a Novel Class of Bradykinin B2 Receptor Antagonist Peptide from Ranid Frogs

OpenAIRE

Ma, Jie; Luo, Yu; Ge, Lilin; Wang, Lei; Zhou, Mei; Zhang, Yingqi; Duan, Jinao; Chen, Tianbao; Shaw, Chris

2014-01-01

The defensive skin secretions of many amphibians are a rich source of bradykinins and bradykinin-related peptides (BRPs). Members of this peptide group are also common components of reptile and arthropod venoms due to their multiple biological functions that include induction of pain, effects on many smooth muscle types, and lowering systemic blood pressure. While most BRPs are bradykinin receptor agonists, some have curiously been found to be exquisite antagonists, such as the maximakinin ge...

Laminin-111-derived peptide conjugated fibrin hydrogel restores salivary gland function.

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Kihoon Nam

Full Text Available Hyposalivation reduces the patient quality of life, as saliva is important for maintaining oral health. Current treatments for hyposalivation are limited to medications such as the muscarinic receptor agonists, pilocarpine and cevimeline. However, these therapies only provide temporary relief. Therefore, alternative therapies are essential to restore salivary gland function. An option is to use bioengineered scaffolds to promote functional salivary gland regeneration. Previous studies demonstrated that the laminin-111 protein is critical for intact salivary gland cell cluster formation and organization. However, laminin-111 protein as a whole is not suitable for clinical applications as some protein domains may contribute to unwanted side effects such as degradation, tumorigenesis and immune responses. Conversely, the use of synthetic laminin-111 peptides makes it possible to minimize the immune reactivity or pathogen transfer. In addition, it is relatively simple and inexpensive as compared to animal-derived proteins. Therefore, the goal of this study was to demonstrate whether a 20 day treatment with laminin-111-derived peptide conjugated fibrin hydrogel promotes tissue regeneration in submandibular glands of a wound healing mouse model. In this study, laminin-111-derived peptide conjugated fibrin hydrogel significantly accelerated formation of salivary gland tissue. The regenerated gland tissues displayed not only structural but also functional restoration.

A novel dual GLP-1 and GIP receptor agonist is neuroprotective in the MPTP mouse model of Parkinson's disease by increasing expression of BNDF.

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Ji, Chenhui; Xue, Guo-Fang; Lijun, Cao; Feng, Peng; Li, Dongfang; Li, Lin; Li, Guanglai; Hölscher, Christian

2016-03-01

The incretins glucagon-like peptide 1 (GLP-1) and glucose dependent insulinotropic polypeptide (GIP) are growth factors with neuroprotective properties. GLP-1 mimetics are on the market as treatments for type 2 diabetes and are well tolerated. Both GLP-1 and GIP mimetics have shown neuroprotective properties in animal models of Parkinson's and Alzheimer's disease. In addition, the GLP-1 mimetic exendin-4 has shown protective effects in a clinical trial in Parkinson's disease (PD) patients. Novel GLP-1/GIP dual-agonist peptides have been developed and are tested in diabetic patients. Here we demonstrate the neuroprotective effects of a novel dual agonist (DA-JC1) in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. MPTP was injected once-daily (20 mg/kg i.p.) for 7 days, and the dual agonist was injected 30 min later i.p. (50 nmol/kg bw). The PI3k inhibitor LY294002 (0.6 mg/kg i.v.) was co-injected in one group. DA-JC1 reduced or reversed most of the MPTP induced motor impairments in the rotarod and in a muscle strength test. The number of tyrosine hydroxylase (TH) positive neurons in the substantia nigra (SN) was reduced by MPTP and increased by DA-JC1. The ratio of anti-inflammatory Bcl-2 to pro-inflammatory BAX as well as the activation of the growth factor kinase Akt was reduced by MPTP and reversed by DA-JC1. The PI3k inhibitor had only limited effect on the DA-JC1 drug effect. Importantly, levels of the neuroprotective brain derived neurotropic factor (BDNF) were reduced by MPTP and enhanced by DA-JC1. The results demonstrate that DA-JC1 shows promise as a novel treatment for PD. Copyright © 2016. Published by Elsevier B.V.

Sports doping: emerging designer and therapeutic β2-agonists.

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Fragkaki, A G; Georgakopoulos, C; Sterk, S; Nielen, M W F

2013-10-21

Beta2-adrenergic agonists, or β2-agonists, are considered essential bronchodilator drugs in the treatment of bronchial asthma, both as symptom-relievers and, in combination with inhaled corticosteroids, as disease-controllers. The use of β2-agonists is prohibited in sports by the World Anti-Doping Agency (WADA) due to claimed anabolic effects, and also, is prohibited as growth promoters in cattle fattening in the European Union. This paper reviews the last seven-year (2006-2012) literature concerning the development of novel β2-agonists molecules either by modifying the molecule of known β2-agonists or by introducing moieties producing indole-, adamantyl- or phenyl urea derivatives. New emerging β2-agonists molecules for future therapeutic use are also presented, intending to emphasize their potential use for doping purposes or as growth promoters in the near future. © 2013.

Automatic computation of radioimmunoassay data. Insulin and C-peptide

Energy Technology Data Exchange (ETDEWEB)

Toyota, T; Kudo, M; Abe, K [Hirosaki Univ., Aomori (Japan). School of Medicine; Kawamata, F; Uehata, S

1975-09-01

Radioimmunoassay provided dose response curves which showed linearity by the use of logistic transformation (Rodbard). This transformation which was applicable to radioimmunoassay should be useful for the computer processing of insulin and C-peptide assay. In the present studies, standard curves were analysed by testing the fit of analytic functions to radioimmunoassay of insulin and C-peptides. A program for use in combination with the double antibody technique was made by Dr. Kawamata. This approach was evidenced to be useful in order to allow automatic computation of data derived from the double antibody assays of insulin and C-peptides. Automatic corrected calculations of radioimmunoassay data of insulin was found to be satisfactory.

Exploring the binding energy profiles of full agonists, partial agonists, and antagonists of the α7 nicotinic acetylcholine receptor.

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Tabassum, Nargis; Ma, Qianyun; Wu, Guanzhao; Jiang, Tao; Yu, Rilei

2017-09-01

Nicotinic acetylcholine receptors (nAChRs) belong to the Cys-loop receptor family and are important drug targets for the treatment of neurological diseases. However, the precise determinants of the binding efficacies of ligands for these receptors are unclear. Therefore, in this study, the binding energy profiles of various ligands (full agonists, partial agonists, and antagonists) were quantified by docking those ligands with structural ensembles of the α7 nAChR exhibiting different degrees of C-loop closure. This approximate treatment of interactions suggested that full agonists, partial agonists, and antagonists of the α7 nAChR possess distinctive binding energy profiles. Results from docking revealed that ligand binding efficacy may be related to the capacity of the ligand to stabilize conformational states with a closed C loop.

The cardiovascular safety trials of DPP-4 inhibitors, GLP-1 agonists, and SGLT2 inhibitors.

Science.gov (United States)

Secrest, Matthew H; Udell, Jacob A; Filion, Kristian B

2017-04-01

In this paper, we review the results of large, double-blind, placebo-controlled randomized trials mandated by the US Food and Drug Administration to examine the cardiovascular safety of newly-approved antihyperglycemic agents in patients with type 2 diabetes. The cardiovascular effects of dipeptidyl peptidase-4 (DPP-4) inhibitors remain controversial: while these drugs did not reduce or increase the risk of primary, pre-specified composite cardiovascular outcomes, one DPP-4 inhibitor (saxagliptin) increased the risk of hospitalization for heart failure in the overall population; another (alogliptin) demonstrated inconsistent effects on heart failure hospitalization across subgroups of patients, and a third (sitagliptin) demonstrated no effect on heart failure. Evidence for cardiovascular benefits of glucagon-like peptide-1 (GLP-1) agonists has been similarly heterogeneous, with liraglutide and semaglutide reducing the risk of composite cardiovascular outcomes, but lixisenatide having no reduction or increase in cardiovascular risk. The effect of GLP-1 agonists on retinopathy remains a potential concern. In the only completed trial to date to assess a sodium-glucose cotransporter-2 (SGLT2) inhibitor, empagliflozin reduced the risk of composite cardiovascular endpoints, predominantly through its impact on cardiovascular mortality and heart failure hospitalization. Copyright © 2017 Elsevier Inc. All rights reserved.

Analysis of iodinated quorum sensing peptides by LC–UV/ESI ion trap mass spectrometry

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Yorick Janssens

2018-02-01

Full Text Available Five different quorum sensing peptides (QSP were iodinated using different iodination techniques. These iodinated peptides were analyzed using a C18 reversed phase HPLC system, applying a linear gradient of water and acetonitrile containing 0.1% (m/v formic acid as mobile phase. Electrospray ionization (ESI ion trap mass spectrometry was used for the identification of the modified peptides, while semi-quantification was performed using total ion current (TIC spectra. Non-iodinated peptides and mono- and di-iodinated peptides (NIP, MIP and DIP respectively were well separated and eluted in that order. Depending on the used iodination method, iodination yields varied from low (2% to high (57%.

Gonadotropin releasing hormone agonists: Expanding vistas

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Navneet Magon

2011-01-01

Full Text Available Gonadotropin-releasing hormone (GnRH agonists are derived from native GnRH by amino acid substitution which yields the agonist resistant to degradation and increases its half-life. The hypogonadotropic hypogonadal state produced by GnRH agonists has been often dubbed as "pseudomenopause" or "medical oophorectomy," which are both misnomers. GnRH analogues (GnRH-a work by temporarily "switching off" the ovaries. Ovaries can be "switched off" for the therapy and therapeutic trial of many conditions which include but are not limited to subfertility, endometriosis, adenomyosis, uterine leiomyomas, precocious puberty, premenstrual dysphoric disorder, chronic pelvic pain, or the prevention of menstrual bleeding in special clinical situations. Rapidly expanding vistas of usage of GnRH agonists encompass use in sex reassignment of male to female transsexuals, management of final height in cases of congenital adrenal hyperplasia, and preserving ovarian function in women undergoing cytotoxic chemotherapy. Hypogonadic side effects caused by the use of GnRH agonists can be tackled with use of "add-back" therapy. Goserelin, leuprolide, and nafarelin are commonly used in clinical practice. GnRH-a have provided us a powerful therapeutic approach to the treatment of numerous conditions in reproductive medicine. Recent synthesis of GnRH antagonists with a better tolerability profile may open new avenues for both research and clinical applications. All stakeholders who are partners in women′s healthcare need to join hands to spread awareness so that these drugs can be used to realize their full potential.

Positive versus negative modulation of different endogenous chemokines for CC-chemokine receptor 1 by small molecule agonists through allosteric versus orthosteric binding

DEFF Research Database (Denmark)

Jensen, Pia C; Thiele, Stefanie; Ulven, Trond

2008-01-01

7 transmembrane-spanning (7TM) chemokine receptors having multiple endogenous ligands offer special opportunities to understand the molecular basis for allosteric mechanisms. Thus, CC-chemokine receptor 1 (CCR1) binds CC-chemokine 3 and 5 (CCL3 and CCL5) with K(d) values of 7.3 and 0.16 nm......5 and not CCL3 activation is affected by substitutions in the main ligand binding pocket including the conserved GluVII:06 anchor point. A series of metal ion chelator complexes were found to act as full agonists on CCR1 and to be critically affected by the same substitutions in the main ligand...... binding pocket as CCL5 but not by mutations in the extracellular domain. In agreement with the overlapping binding sites, the small non-peptide agonists displaced radiolabeled CCL5 with high affinity. Interestingly, the same compounds acted as allosteric enhancers of the binding of CCL3, with which...

Melatonin Receptor Agonists as the "Perioceutics" Agents for Periodontal Disease through Modulation of Porphyromonas gingivalis Virulence and Inflammatory Response.

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Wei Zhou

Full Text Available "Perioceutics" including antimicrobial therapy and host modulatory therapy has emerged as a vital adjunctive treatment of periodontal disease. Melatonin level was significantly reduced in patients with periodontal diseases suggesting melatonin could be applied as a potential "perioceutics" treatment of periodontal diseases. This study aims to investigate the effects of melatonin receptor agonists (melatonin and ramelteon on Porphyromonas gingivalis virulence and Porphyromonas gingivalis-derived lipopolysaccharide (Pg-LPS-induced inflammation.Effects of melatonin receptor agonists on Porphyromonas gingivalis planktonic cultures were determined by microplate dilution assays. Formation, reduction, and viability of Porphyromonas gingivalis biofilms were detected by crystal violet staining and MTT assays, respectively. Meanwhile, biofilms formation was also observed by confocal laser scanning microscopy (CLSM. The effects on gingipains and hemolytic activities of Porphyromonas gingivalis were evaluated using chromogenic peptides and sheep erythrocytes. The mRNA expression of virulence and iron/heme utilization was assessed using RT-PCR. In addition, cell viability of melatonin receptor agonists on human gingival fibroblasts (HGFs was evaluated by MTT assays. After pretreatment of melatonin receptor agonists, HGFs were stimulated with Pg-LPS and then release of cytokines (IL-6 and lL-8 was measured by enzyme-linked immunosorbent assay (ELISA.Melatonin and ramelteon did exhibit antimicrobial effects against planktonic culture. Importantly, they inhibited biofilm formation, reduced the established biofilms, and decreased biofilm viability of Porphyromonas gingivalis. Furthermore, they at sub-minimum inhibitory concentration (sub-MIC concentrations markedly inhibited the proteinase activities of gingipains and hemolysis in a dose-dependent manner. They at sub-MIC concentrations significantly inhibited the mRNA expression of virulence factors (kgp, rgp

Melatonin Receptor Agonists as the "Perioceutics" Agents for Periodontal Disease through Modulation of Porphyromonas gingivalis Virulence and Inflammatory Response.

Science.gov (United States)

Zhou, Wei; Zhang, Xuan; Zhu, Cai-Lian; He, Zhi-Yan; Liang, Jing-Ping; Song, Zhong-Chen

2016-01-01

"Perioceutics" including antimicrobial therapy and host modulatory therapy has emerged as a vital adjunctive treatment of periodontal disease. Melatonin level was significantly reduced in patients with periodontal diseases suggesting melatonin could be applied as a potential "perioceutics" treatment of periodontal diseases. This study aims to investigate the effects of melatonin receptor agonists (melatonin and ramelteon) on Porphyromonas gingivalis virulence and Porphyromonas gingivalis-derived lipopolysaccharide (Pg-LPS)-induced inflammation. Effects of melatonin receptor agonists on Porphyromonas gingivalis planktonic cultures were determined by microplate dilution assays. Formation, reduction, and viability of Porphyromonas gingivalis biofilms were detected by crystal violet staining and MTT assays, respectively. Meanwhile, biofilms formation was also observed by confocal laser scanning microscopy (CLSM). The effects on gingipains and hemolytic activities of Porphyromonas gingivalis were evaluated using chromogenic peptides and sheep erythrocytes. The mRNA expression of virulence and iron/heme utilization was assessed using RT-PCR. In addition, cell viability of melatonin receptor agonists on human gingival fibroblasts (HGFs) was evaluated by MTT assays. After pretreatment of melatonin receptor agonists, HGFs were stimulated with Pg-LPS and then release of cytokines (IL-6 and lL-8) was measured by enzyme-linked immunosorbent assay (ELISA). Melatonin and ramelteon did exhibit antimicrobial effects against planktonic culture. Importantly, they inhibited biofilm formation, reduced the established biofilms, and decreased biofilm viability of Porphyromonas gingivalis. Furthermore, they at sub-minimum inhibitory concentration (sub-MIC) concentrations markedly inhibited the proteinase activities of gingipains and hemolysis in a dose-dependent manner. They at sub-MIC concentrations significantly inhibited the mRNA expression of virulence factors (kgp, rgpA, rgpB, hag

Sports doping: Emerging designer and therapeutic B2-agonists

NARCIS (Netherlands)

Fragkaki, A.G.; Georgakopoulos, C.; Sterk, S.S.; Nielen, M.W.F.

2013-01-01

Beta2-adrenergic agonists, or ß2-agonists, are considered essential bronchodilator drugs in the treatment of bronchial asthma, both as symptom-relievers and, in combination with inhaled corticosteroids, as disease-controllers. The use of ß2-agonists is prohibited in sports by the World Anti-Doping

EPMLR: sequence-based linear B-cell epitope prediction method using multiple linear regression.

Science.gov (United States)

Lian, Yao; Ge, Meng; Pan, Xian-Ming

2014-12-19

B-cell epitopes have been studied extensively due to their immunological applications, such as peptide-based vaccine development, antibody production, and disease diagnosis and therapy. Despite several decades of research, the accurate prediction of linear B-cell epitopes has remained a challenging task. In this work, based on the antigen's primary sequence information, a novel linear B-cell epitope prediction model was developed using the multiple linear regression (MLR). A 10-fold cross-validation test on a large non-redundant dataset was performed to evaluate the performance of our model. To alleviate the problem caused by the noise of negative dataset, 300 experiments utilizing 300 sub-datasets were performed. We achieved overall sensitivity of 81.8%, precision of 64.1% and area under the receiver operating characteristic curve (AUC) of 0.728. We have presented a reliable method for the identification of linear B cell epitope using antigen's primary sequence information. Moreover, a web server EPMLR has been developed for linear B-cell epitope prediction: http://www.bioinfo.tsinghua.edu.cn/epitope/EPMLR/ .

Treatment potential of the GLP-1 receptor agonists in type 2 diabetes mellitus

DEFF Research Database (Denmark)

Østergaard, L; Frandsen, Christian S.; Madsbad, S

2016-01-01

Over the last decade, the discovery of glucagon-like peptide 1 receptor agonists (GLP-1 RAs) has increased the treatment options for patients with type 2 diabetes mellitus (T2DM). GLP-1 RAs mimic the effects of native GLP-1, which increases insulin secretion, inhibits glucagon secretion, increases...... satiety and slows gastric emptying. This review evaluates the phase III trials for all approved GLP-1 RAs and reports that all GLP-1 RAs decrease HbA1c, fasting plasma glucose, and lead to a reduction in body weight in the majority of trials. The most common adverse events are nausea and other...... gastrointestinal discomfort, while hypoglycaemia is rarely reported when GLP-1 RAs not are combined with sulfonylurea or insulin. Treatment options in the near future will include co-formulations of basal insulin and a GLP-1 RA....

Precursors of vertebrate peptide antibiotics dermaseptin b and adenoregulin have extensive sequence identities with precursors of opioid peptides dermorphin, dermenkephalin, and deltorphins.

Science.gov (United States)

Amiche, M; Ducancel, F; Mor, A; Boulain, J C; Menez, A; Nicolas, P

1994-07-08

The dermaseptins are a family of broad spectrum antimicrobial peptides, 27-34 amino acids long, involved in the defense of the naked skin of frogs against microbial invasion. They are the first vertebrate peptides to show lethal effects against the filamentous fungi responsible for severe opportunistic infections accompanying immunodeficiency syndrome and the use of immunosuppressive agents. A cDNA library was constructed from skin poly(A+) RNA of the arboreal frog Phyllomedusa bicolor and screened with an oligonucleotide probe complementary to the COOH terminus of dermaseptin b. Several clones contained a full-length DNA copy of a 443-nucleotide mRNA that encoded a 78-residue dermaseptin b precursor protein. The deduced precursor contained a putative signal sequence at the NH2 terminus, a 20-residue spacer sequence extremely rich (60%) in glutamic and aspartic acids, and a single copy of a dermaseptin b progenitor sequence at the COOH terminus. One clone contained a complete copy of adenoregulin, a 33-residue peptide reported to enhance the binding of agonists to the A1 adenosine receptor. The mRNAs encoding adenoregulin and dermaseptin b were very similar: 70 and 75% nucleotide identities between the 5'- and 3'-untranslated regions, respectively; 91% amino acid identity between the signal peptides; 82% identity between the acidic spacer sequences; and 38% identity between adenoregulin and dermaseptin b. Because adenoregulin and dermaseptin b have similar precursor designs and antimicrobial spectra, adenoregulin should be considered as a new member of the dermaseptin family and alternatively named dermaseptin b II. Preprodermaseptin b and preproadenoregulin have considerable sequence identities to the precursors encoding the opioid heptapeptides dermorphin, dermenkephalin, and deltorphins. This similarity extended into the 5'-untranslated regions of the mRNAs. These findings suggest that the genes encoding the four preproproteins are all members of the same family

Antimicrobial peptides design by evolutionary multiobjective optimization.

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Giuseppe Maccari

Full Text Available Antimicrobial peptides (AMPs are an abundant and wide class of molecules produced by many tissues and cell types in a variety of mammals, plant and animal species. Linear alpha-helical antimicrobial peptides are among the most widespread membrane-disruptive AMPs in nature, representing a particularly successful structural arrangement in innate defense. Recently, AMPs have received increasing attention as potential therapeutic agents, owing to their broad activity spectrum and their reduced tendency to induce resistance. The introduction of non-natural amino acids will be a key requisite in order to contrast host resistance and increase compound's life. In this work, the possibility to design novel AMP sequences with non-natural amino acids was achieved through a flexible computational approach, based on chemophysical profiles of peptide sequences. Quantitative structure-activity relationship (QSAR descriptors were employed to code each peptide and train two statistical models in order to account for structural and functional properties of alpha-helical amphipathic AMPs. These models were then used as fitness functions for a multi-objective evolutional algorithm, together with a set of constraints for the design of a series of candidate AMPs. Two ab-initio natural peptides were synthesized and experimentally validated for antimicrobial activity, together with a series of control peptides. Furthermore, a well-known Cecropin-Mellitin alpha helical antimicrobial hybrid (CM18 was optimized by shortening its amino acid sequence while maintaining its activity and a peptide with non-natural amino acids was designed and tested, demonstrating the higher activity achievable with artificial residues.

A 12-week treatment with the long-acting glucagon-like peptide 1 receptor agonist liraglutide leads to significant weight loss in a subset of obese women with newly diagnosed polycystic ovary syndrome.

Science.gov (United States)

Jensterle, Mojca; Kravos, Nika Aleksandra; Pfeifer, Marija; Kocjan, Tomaz; Janez, Andrej

2015-01-01

The long-acting glucagon-like peptide 1 receptor agonist liraglutide is linked to progressive and sustained weight loss in obese people with diabetes. However, its efficacy and safety in women with polycystic ovary syndrome (PCOS) has not yet been addressed. Thirty-two obese women (aged 27.6±7.2 years, BMI 39.5±6.2 kg/m(2)) with newly diagnosed PCOS were randomized to receive either liraglutide 1.2 mg QD sc (n=17) or metformin 1000 mg BID po (n=15) for 12 weeks; 28 patients completed the study (14 on liraglutide and 14 on metformin). The main outcome was change in body weight. Intention-to-treat analysis showed significant BMI (-0.98 kg/m(2); pweight (-2.52 kg; p2), severe obesity and higher odds ratio for the metabolic syndrome (OR=3.9), the patients fared much better with liraglutide than with metformin (mean BMI decreased 2.13 kg/m(2) vs. 0.62 kg/m(2), respectively). Short-term liraglutide treatment was associated with significant weight loss in a subset of obese patients with newly diagnosed PCOS and a higher metabolic risk profile.

Electric fields control the orientation of peptides irreversibly immobilized on radical-functionalized surfaces.

Science.gov (United States)

Martin, Lewis J; Akhavan, Behnam; Bilek, Marcela M M

2018-01-24

Surface functionalization of an implantable device with bioactive molecules can overcome adverse biological responses by promoting specific local tissue integration. Bioactive peptides have advantages over larger protein molecules due to their robustness and sterilizability. Their relatively small size presents opportunities to control the peptide orientation on approach to a surface to achieve favourable presentation of bioactive motifs. Here we demonstrate control of the orientation of surface-bound peptides by tuning electric fields at the surface during immobilization. Guided by computational simulations, a peptide with a linear conformation in solution is designed. Electric fields are used to control the peptide approach towards a radical-functionalized surface. Spontaneous, irreversible immobilization is achieved when the peptide makes contact with the surface. Our findings show that control of both peptide orientation and surface concentration is achieved simply by varying the solution pH or by applying an electric field as delivered by a small battery.

Design, synthesis, and actions of a novel chimeric natriuretic peptide: CD-NP.

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Lisy, Ondrej; Huntley, Brenda K; McCormick, Daniel J; Kurlansky, Paul A; Burnett, John C

2008-07-01

Our aim was to design, synthesize and test in vivo and in vitro a new chimeric peptide that would combine the beneficial properties of 2 distinct natriuretic peptides with a biological profile that goes beyond native peptides. Studies have established the beneficial vascular and antiproliferative properties of C-type natriuretic peptide (CNP). While lacking renal actions, CNP is less hypotensive than the cardiac peptides atrial natriuretic peptide and B-type natriuretic peptide but unloads the heart due to venodilation. Dendroaspis natriuretic peptide is a potent natriuretic and diuretic peptide that is markedly hypotensive and functions via a separate guanylyl cyclase receptor compared with CNP. Here we engineered a novel chimeric peptide CD-NP that represents the fusion of the 22-amino acid peptide CNP together with the 15-amino acid linear C-terminus of Dendroaspis natriuretic peptide. We also determined in vitro in cardiac fibroblasts cyclic guanosine monophosphate-activating and antiproliferative properties of CD-NP. Our studies demonstrate in vivo that CD-NP is natriuretic and diuretic, glomerular filtration rate enhancing, cardiac unloading, and renin inhibiting. CD-NP also demonstrates less hypotensive properties when compared with B-type natriuretic peptide. In addition, CD-NP in vitro activates cyclic guanosine monophosphate and inhibits cardiac fibroblast proliferation. The current findings advance an innovative design strategy in natriuretic peptide drug discovery and development to create therapeutic peptides with favorable properties that may be preferable to those associated with native natriuretic peptides.

The VPAC2 agonist peptide histidine isoleucine (PHI) up-regulates glutamate transport in the corpus callosum of a rat model of amyotrophic lateral sclerosis (hSOD1G93A) by inhibiting caspase-3 mediated inactivation of GLT-1a.

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Goursaud, Stéphanie; Focant, Marylène C; Berger, Julie V; Nizet, Yannick; Maloteaux, Jean-Marie; Hermans, Emmanuel

2011-10-01

Degeneration of corpus callosum appears in patients with amyotrophic lateral sclerosis (ALS) before clinical signs of upper motor neuron death. Considering the ALS-associated impairment of astrocytic glutamate uptake, we have characterized the expression and activity of the glutamate transporter isoforms GLT-1a and GLT-1b in the corpus callosum of transgenic rats expressing a mutated form of the human superoxide dismutase 1 (hSOD1(G93A)). We have also studied the effect of peptide histidine isoleucine (PHI), a vasoactive intestinal peptide (VIP)/pituitary adenylate cyclase-activating polypeptide (PACAP) receptor 2 (VPAC(2)) agonist on glutamate transporters both in vivo and in callosal astrocytes. Before the onset of motor symptoms, the expression of both transporter isoforms was correlated with a constitutive activity of caspase-3. This enzyme participates in the down-regulation of GLT-1 in ALS, and here we demonstrated its involvement in the selective degradation of GLT-1a in the white matter. A single stereotactic injection of PHI into the corpus callosum of symptomatic rats decreased caspase-3 activity and promoted GLT-1a expression and uptake activity. Together, with evidence for a reduced expression of prepro-VIP/PHI mRNA in the corpus callosum of transgenic animals, these data shed light on the modulatory role of the VIP/PHI system on the glutamatergic transmission in ALS.

A novel selective VPAC2 agonist peptide-conjugated chitosan modified selenium nanoparticles with enhanced anti-type 2 diabetes synergy effects

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Zhao SJ

2017-03-01

Full Text Available Shao-Jun Zhao,1,2,* De-Hua Wang,1,2 Yan-Wei Li,1,2 Lei Han,1,2 Xing Xiao,1,2 Min Ma,3,* David Chi-Cheong Wan,4 An Hong,1,2 Yi Ma1,2 1Institute of Biomedicine, Department of Cellular Biology, Jinan University, 2National Engineering Research Center of Genetic Medicine, Key Laboratory of Bioengineering Medicine of Guangdong Province, Jinan University, 3College of traditional Chinese Medicine, Institute of Integrated Traditional Chinese and Western Medicine, Jinan University, Guangdong, 4School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, People’s Republic of China *These authors contributed equally to this work Abstract: A novel neuroendocrine peptide, pituitary adenylate cyclase activating peptide (PACAP, was found to have an important role in carbohydrate or lipid metabolism and was susceptible to dipeptidyl peptidase IV degradation. It can not only mediate glucose-dependent insulin secretion and lower blood glucose by activating VPAC2 receptor, but also raise blood glucose by promoting glucagon production by VPAC1 receptor activation. Therefore, its therapeutic application is restricted by the exceedingly short-acting half-life and the stimulatory function for glycogenolysis. Herein, we generated novel peptide-conjugated selenium nanoparticles (SeNPs; named as SCD, comprising a 32-amino acid PACAP-derived peptide DBAYL that selectively binds to VPAC2, and chitosan-modified SeNPs (SeNPs-CTS, SC as slow-release carrier. The circulating half-life of SCD is 14.12 h in mice, which is 168.4- and 7.1-fold longer than wild PACAP (~5 min and DBAYL (~1.98 h, respectively. SCD (10 nmol/L significantly promotes INS-1 cell proliferation, glucose uptake, insulin secretion, insulin receptor expression and also obviously reduces intracellular reactive oxygen species levels in H2O2-injured INS-1 cells. Furthermore, the biological effects of SCD are stronger than Exendin-4 (a clinically approved drug

Modification of opiate agonist binding by pertussis toxin

Energy Technology Data Exchange (ETDEWEB)

Abood, M.E.; Lee, N.M.; Loh, H.H.

1986-03-05

Opiate agonist binding is decreased by GTP, suggesting the possible involvement of GTP binding proteins in regulation of opiate receptor binding. This possibility was addressed by asking whether pertussis toxin treatment, which results in ADP-ribosylation and modification of G proteins, would alter opiate agonist binding. The striatum was chosen for the initial brain area to be studied, since regulation of opiate action in this area had been shown to be modified by pertussis toxin. Treatment of striatal membranes with pertussis toxin results in up to a 55% decrease in /sup 3/(H)-DADLE binding as compared with membranes treated identically without toxin. This corresponds to a near complete ADP-ribosylation of both G proteins in the striatal membrane. The decrease in agonist binding appears to be due to an altered affinity of the receptor for agonist as opposed to a decrease in the number of sites. This effect of pertussis toxin on opiate agonist binding demonstrates the actual involvement of G proteins in regulation of opiate receptor binding.

Modification of opiate agonist binding by pertussis toxin

International Nuclear Information System (INIS)

Abood, M.E.; Lee, N.M.; Loh, H.H.

1986-01-01

Opiate agonist binding is decreased by GTP, suggesting the possible involvement of GTP binding proteins in regulation of opiate receptor binding. This possibility was addressed by asking whether pertussis toxin treatment, which results in ADP-ribosylation and modification of G proteins, would alter opiate agonist binding. The striatum was chosen for the initial brain area to be studied, since regulation of opiate action in this area had been shown to be modified by pertussis toxin. Treatment of striatal membranes with pertussis toxin results in up to a 55% decrease in 3 (H)-DADLE binding as compared with membranes treated identically without toxin. This corresponds to a near complete ADP-ribosylation of both G proteins in the striatal membrane. The decrease in agonist binding appears to be due to an altered affinity of the receptor for agonist as opposed to a decrease in the number of sites. This effect of pertussis toxin on opiate agonist binding demonstrates the actual involvement of G proteins in regulation of opiate receptor binding

Melatonin Receptor Agonists as the “Perioceutics” Agents for Periodontal Disease through Modulation of Porphyromonas gingivalis Virulence and Inflammatory Response

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Zhu, Cai-Lian; He, Zhi-Yan; Liang, Jing-Ping; Song, Zhong-Chen

2016-01-01

Aim “Perioceutics” including antimicrobial therapy and host modulatory therapy has emerged as a vital adjunctive treatment of periodontal disease. Melatonin level was significantly reduced in patients with periodontal diseases suggesting melatonin could be applied as a potential “perioceutics” treatment of periodontal diseases. This study aims to investigate the effects of melatonin receptor agonists (melatonin and ramelteon) on Porphyromonas gingivalis virulence and Porphyromonas gingivalis-derived lipopolysaccharide (Pg-LPS)-induced inflammation. Methods Effects of melatonin receptor agonists on Porphyromonas gingivalis planktonic cultures were determined by microplate dilution assays. Formation, reduction, and viability of Porphyromonas gingivalis biofilms were detected by crystal violet staining and MTT assays, respectively. Meanwhile, biofilms formation was also observed by confocal laser scanning microscopy (CLSM). The effects on gingipains and hemolytic activities of Porphyromonas gingivalis were evaluated using chromogenic peptides and sheep erythrocytes. The mRNA expression of virulence and iron/heme utilization was assessed using RT-PCR. In addition, cell viability of melatonin receptor agonists on human gingival fibroblasts (HGFs) was evaluated by MTT assays. After pretreatment of melatonin receptor agonists, HGFs were stimulated with Pg-LPS and then release of cytokines (IL-6 and lL-8) was measured by enzyme-linked immunosorbent assay (ELISA). Results Melatonin and ramelteon did exhibit antimicrobial effects against planktonic culture. Importantly, they inhibited biofilm formation, reduced the established biofilms, and decreased biofilm viability of Porphyromonas gingivalis. Furthermore, they at sub-minimum inhibitory concentration (sub-MIC) concentrations markedly inhibited the proteinase activities of gingipains and hemolysis in a dose-dependent manner. They at sub-MIC concentrations significantly inhibited the mRNA expression of virulence

Hypersensitive detection and quantitation of BoNT/A by IgY antibody against substrate linear-peptide.

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Tao Li

Full Text Available Botulinum neurotoxin A (BoNT/A, the most acutely poisonous substance to humans known, cleave its SNAP-25 substrate with high specificity. Based on the endopeptidase activity, different methods have been developed to detect BoNT/A, but most lack ideal reproducibility or sensitivity, or suffer from long-term or unwanted interferences. In this study, we developed a simple method to detect and quantitate trace amounts of botulinum neurotoxin A using the IgY antibody against a linear-peptide substrate. The effects of reaction buffer, time, and temperature were analyzed and optimized. When the optimized assay was used to detect BoNT/A, the limit of detection of the assay was 0.01 mouse LD50 (0.04 pg, and the limit of quantitation was 0.12 mouse LD50/ml (0.48 pg. The findings also showed favorable specificity of detecting BoNT/A. When used to detect BoNT/A in milk or human serum, the proposed assay exhibited good quantitative accuracy (88% < recovery < 111%; inter- and intra-assay CVs < 18%. This method of detection took less than 3 h to complete, indicating that it can be a valuable method of detecting BoNT/A in food or clinical diagnosis.

Design, Synthesis and Evaluation of Branched RRWQWR-Based Peptides as Antibacterial Agents Against Clinically Relevant Gram-Positive and Gram-Negative Pathogens

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Sandra C. Vega

2018-03-01

Full Text Available Multidrug resistance of pathogenic bacteria has become a public health crisis that requires the urgent design of new antibacterial drugs such as antimicrobial peptides (AMPs. Seeking to obtain new, lactoferricin B (LfcinB-based synthetic peptides as viable early-stage candidates for future development as AMPs against clinically relevant bacteria, we designed, synthesized and screened three new cationic peptides derived from bovine LfcinB. These peptides contain at least one RRWQWR motif and differ by the copy number (monomeric, dimeric or tetrameric and structure (linear or branched of this motif. They comprise a linear palindromic peptide (RWQWRWQWR, a dimeric peptide (RRWQWR2KAhx and a tetrameric peptide (RRWQWR4K2Ahx2C2. They were screened for antibacterial activity against Enterococcus faecalis (ATCC 29212 and ATCC 51575 strains, Pseudomonas aeruginosa (ATCC 10145 and ATCC 27853 strains and clinical isolates of two Gram-positive bacteria (Enterococcus faecium and Staphylococcus aureus and two Gram-negative bacteria (Klebsiella pneumoniae and Pseudomonas aeruginosa. All three peptides exhibited greater activity than did the reference peptide, LfcinB (17–31, which contains a single linear RRWQWR motif. Against the ATCC reference strains, the three new peptides exhibited minimum inhibitory concentration (MIC50 values of 3.1–198.0 μM and minimum bactericidal concentration (MBC values of 25–200 μM, and against the clinical isolates, MIC50 values of 1.6–75.0 μM and MBC values of 12.5–100 μM. However, the tetrameric peptide was also found to be strongly hemolytic (49.1% at 100 μM. Scanning Electron Microscopy (SEM demonstrated that in the dimeric and tetrameric peptides, the RRWQWR motif is exposed to the pathogen surface. Our results may inform the design of new, RRWQWR-based AMPs.

Molecular cloning of a cDNA encoding the precursor of adenoregulin from frog skin. Relationships with the vertebrate defensive peptides, dermaseptins.

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Amiche, M; Ducancel, F; Lajeunesse, E; Boulain, J C; Ménez, A; Nicolas, P

1993-03-31

Adenoregulin has recently been isolated from Phyllomedusa skin as a 33 amino acid residues peptide which enhanced binding of agonists to the A1 adenosine receptor. In order to study the structure of the precursor of adenoregulin we constructed a cDNA library from mRNAs extracted from the skin of Phyllomedusa bicolor. We detected the complete nucleotide sequence of a cDNA encoding the adenoregulin biosynthetic precursor. The deduced sequence of the precursor is 81 amino acids long, exhibits a putative signal sequence at the NH2 terminus and contains a single copy of the biologically active peptide at the COOH terminus. Structural and conformational homologies that are observed between adenoregulin and the dermaseptins, antimicrobial peptides exhibiting strong membranolytic activities against various pathogenic agents, suggest that adenoregulin is an additional member of the growing family of cytotropic antimicrobial peptides that allow vertebrate animals to defend themselves against microorganisms. As such, the adenosine receptor regulating activity of adenoregulin could be due to its ability to interact with and disrupt membranes lipid bilayers.

HBA1C CONTROL AND COST-EFFECTIVENESS IN PATIENTS WITH TYPE 2 DIABETES MELLITUS INITIATED ON CANAGLIFLOZIN OR A GLUCAGON-LIKE PEPTIDE 1 RECEPTOR AGONIST IN A REAL-WORLD SETTING.

Science.gov (United States)

Wysham, Carol H; Pilon, Dominic; Ingham, Mike; Lafeuille, Marie-Hélène; Emond, Bruno; Kamstra, Rhiannon; Pfeifer, Michael; Lefebvre, Patrick

2018-03-01

To compare glycated hemoglobin (HbA1c) control and medication costs between patients with type 2 diabetes mellitus (T2DM) treated with canagliflozin 300 mg (CANA) or a glucagon-like peptide 1 receptor agonist (GLP-1 RA) in a real-world setting. Adults with T2DM newly initiated on CANA or a GLP-1 RA (index date) were identified from IQVIA ™ Real-World Data Electronic Medical Records U.S. database (March 29, 2012-April 30, 2016). Inverse probability of treatment weighting accounted for differences in baseline characteristics. HbA1c levels at 3-month intervals were compared using generalized estimating equations. Medication costs used wholesale acquisition costs. For both cohorts (CANA: n = 11,435; GLP-1 RA: n = 11,582), HbA1c levels decreased at 3 months postindex and remained lower through 30 months. Absolute changes in mean HbA1c from index to 3 months postindex for CANA and GLP-1 RA were -1.16% and -1.21% (patients with baseline HbA1c ≥7% [53 mmol/mol]); -1.54% and -1.51% (patients with baseline HbA1c ≥8% [64 mmol/mol]); and -2.13% and -1.99% (patients with baseline HbA1c ≥9% [75 mmol/mol]), respectively. Postindex, CANA patients with baseline HbA1c ≥7% had similar HbA1c levels at each interval versus GLP-1 RA patients, except 9 months (mean HbA1c, 7.75% [61 mmol/mol] vs. 7.86% [62 mmol/mol]; P = .0305). CANA patients with baseline HbA1c ≥8% and ≥9% had consistently lower HbA1c numerically versus GLP-1 RA patients and statistically lower HbA1c at 9 (baseline HbA1c ≥8% or ≥9%), 27, and 30 months (baseline HbA1c ≥9%). Continuous 12-month medication cost $3,326 less for CANA versus GLP-1 RA. This retrospective study demonstrated a similar evolution of HbA1c levels among CANA and GLP-1 RA patients in a real-world setting. Lower medication costs suggest CANA is economically dominant over GLP-1 RA (similar effectiveness, lower cost). AHA = antihyperglycemic agent BMI = body mass index CANA = canagliflozin 300 mg DCSI = diabetes complications severity

Reciprocity of agonistic support in ravens.

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Fraser, Orlaith N; Bugnyar, Thomas

2012-01-01

Cooperative behaviour through reciprocation or interchange of valuable services in primates has received considerable attention, especially regarding the timeframe of reciprocation and its ensuing cognitive implications. Much less, however, is known about reciprocity in other animals, particularly birds. We investigated patterns of agonistic support (defined as a third party intervening in an ongoing conflict to attack one of the conflict participants, thus supporting the other) in a group of 13 captive ravens, Corvus corax. We found support for long-term, but not short-term, reciprocation of agonistic support. Ravens were more likely to support individuals who preened them, kin and dominant group members. These results suggest that ravens do not reciprocate on a calculated tit-for-tat basis, but aid individuals from whom reciprocated support would be most useful and those with whom they share a good relationship. Additionally, dyadic levels of agonistic support and consolation (postconflict affiliation from a bystander to the victim) correlated strongly with each other, but we found no evidence to suggest that receiving agonistic support influences the victim's likelihood of receiving support (consolation) after the conflict ends. Our findings are consistent with an emotionally mediated form of reciprocity in ravens and provide additional support for convergent cognitive evolution in birds and mammals.

Peptides identify multiple hotspots within the ligand binding domain of the TNF receptor 2

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Lennick Michael

2003-01-01

Full Text Available Abstract Background Hotspots are defined as the minimal functional domains involved in protein:protein interactions and sufficient to induce a biological response. Results Here we describe the use of complex and high diversity phage display libraries to isolate peptides (called Hotspot Ligands or HSPLs which sub-divide the ligand binding domain of the tumor necrosis factor receptor 2 (TNFR2; p75 into multiple hotspots. We have shown that these libraries could generate HSPLs which not only subdivide hotspots on protein and non-protein targets but act as agonists or antagonists. Using this approach, we generated peptides which were specific for human TNFR2, could be competed by the natural ligands, TNFα and TNFβ and induced an unexpected biological response in a TNFR2-specific manner. Conclusions To our knowledge, this is the first report describing the dissection of the TNFR2 into biologically active hotspots with the concomitant identification of a novel and unexpected biological activity.

Using Gas-Phase Guest-Host Chemistry to Probe the Structures of b Ions of Peptides

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Somogyi, Árpád; Harrison, Alex G.; Paizs, Béla

2012-12-01

Middle-sized b n ( n ≥ 5) fragments of protonated peptides undergo selective complex formation with ammonia under experimental conditions typically used to probe hydrogen-deuterium exchange in Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Other usual peptide fragments like y, a, a*, etc., and small b n ( n ≤ 4) fragments do not form stable ammonia adducts. We propose that complex formation of b n ions with ammonia is characteristic to macrocyclic isomers of these fragments. Experiments on a protonated cyclic peptide and N-terminal acetylated peptides fully support this hypothesis; the protonated cyclic peptide does form ammonia adducts while linear b n ions of acetylated peptides do not undergo complexation. Density functional theory (DFT) calculations on the proton-bound dimers of all-Ala b 4 , b 5 , and b 7 ions and ammonia indicate that the ionizing proton initially located on the peptide fragment transfers to ammonia upon adduct formation. The ammonium ion is then solvated by N+-H…O H-bonds; this stabilization is much stronger for macrocyclic b n isomers due to the stable cage-like structure formed and entropy effects. The present study demonstrates that gas-phase guest-host chemistry can be used to selectively probe structural features (i.e., macrocyclic or linear) of fragments of protonated peptides. Stable ammonia adducts of b 9 , b 9 -A, and b 9 -2A of A8YA, and b 13 of A20YVFL are observed indicating that even these large b-type ions form macrocyclic structures.

Isolation, structure, synthesis, and activity of a new member of the calcitonin gene-related peptide family from frog skin and molecular cloning of its precursor.

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Seon, A A; Pierre, T N; Redeker, V; Lacombe, C; Delfour, A; Nicolas, P; Amiche, M

2000-02-25

Calcitonin gene-related peptide has been extracted from the skin exudate of a single living specimen of the frog Phyllomedusa bicolor and purified to homogeneity by a two-step protocol. A total volume of 250 microl of exudate yielded 380 microg of purified peptide. Mass spectrometric analysis and gas phase sequencing of the purified peptide as well as chemical synthesis and cDNA analysis were consistent with the structure SCDTSTCATQRLADFLSRSGGIGSPDFVPTDVSANSF amide and the presence of a disulfide bridge linking Cys(2) and Cys(7). The skin peptide, named skin calcitonin gene-related peptide, differs significantly from all other members of the calcitonin gene-related peptide family of peptides at nine positions but binds with high affinity to calcitonin gene-related peptide receptors in the rat brain and acts as an agonist in the rat vas deferens bioassay with potencies equal to those of human CGRP. Reverse transcriptase-polymerase chain reaction coupled with cDNA cloning and sequencing demonstrated that skin calcitonin gene-related peptide isolated in the skin is identical to that present in the frog's central and enteric nervous systems. These data, which indicate for the first time the existence of calcitonin gene-related peptide in the frog skin, add further support to the brain-skin-gut triangle hypothesis as a useful tool in the identification and/or isolation of mammalian peptides that are present in the brain and other tissues in only minute quantities.

Chimeric peptide containing both B and T cells epitope of tumor-associated antigen L6 enhances anti-tumor effects in HLA-A2 transgenic mice.

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Lin, Su-I; Huang, Ming-Hsi; Chang, Yu-Wen; Chen, I-Hua; Roffler, Steve; Chen, Bing-Mae; Sher, Yuh-Pyng; Liu, Shih-Jen

2016-07-28

Synthetic peptides are attractive for cancer immunotherapy because of their safety and flexibility. In this report, we identified a new B cell epitope of tumor-associated antigen L6 (TAL6) that could induce antibody-dependent cellular cytotoxicity (ADCC) in vivo. We incorporated the B cell epitope with a cytotoxic T lymphocyte (CTL) and a helper T (Th) epitope to form a chimeric long peptide. We formulated the chimeric peptide with different adjuvants to immunize HLA-A2 transgenic mice and evaluate their immunogenicity. The chimeric peptide formulated with an emulsion type nanoparticle (PELC) adjuvant and a toll-like receptor 9 agonist (CpG ODN) (PELC/CpG) induced the greatest ADCC and CTL responses. The induced anti-tumor immunity inhibited the growth of TAL6-positive cancer cells. Moreover, we observed that immunization with the chimeric peptide inhibited cancer cell migration in vitro and metastasis in vivo. These data suggest that a chimeric peptide containing both B and T cell epitopes of TAL6 formulated with PELC/CpG adjuvant is feasible for cancer immunotherapy. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Driving forces for adsorption of amphiphilic peptides to the air-water interface.

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Engin, Ozge; Villa, Alessandra; Sayar, Mehmet; Hess, Berk

2010-09-02

We have studied the partitioning of amphiphilic peptides at the air-water interface. The free energy of adsorption from bulk to interface was calculated by determining the potential of mean force via atomistic molecular dynamics simulations. To this end a method is introduced to restrain or constrain the center of mass of a group of molecules in a periodic system. The model amphiphilic peptides are composed of alternating valine and asparagine residues. The decomposition of the free energy difference between the bulk and interface is studied for different peptide block lengths. Our analysis revealed that for short amphiphilic peptides the surface driving force dominantly stems from the dehydration of hydrophobic side chains. The only opposing force is associated with the loss of orientational freedom of the peptide at the interface. For the peptides studied, the free energy difference scales linearly with the size of the molecule, since the peptides mainly adopt extended conformations both in bulk and at the interface. The free energy difference depends strongly on the water model, which can be rationalized through the hydration thermodynamics of hydrophobic solutes. Finally, we measured the reduction of the surface tension associated with complete coverage of the interface with peptides.

Milk bioactive peptides and beta-casomorphins induce mucus release in rat jejunum.

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Trompette, Aurélien; Claustre, Jean; Caillon, Fabienne; Jourdan, Gérard; Chayvialle, Jean Alain; Plaisancié, Pascale

2003-11-01

Intestinal mucus is critically involved in the protection of the mucosa. An enzymatic casein hydrolysate and beta-casomorphin-7, a mu-opioid peptide generated in the intestine during bovine casein digestion, markedly induce mucus discharge. Because shorter mu-opioid peptides have been described, the effects of the opioid peptides in casein, beta-casomorphin-7, -6, -4, -4NH2 and -3, and of opioid neuropeptides met-enkephalin, dynorphin A and (D-Ala2,N-Me-Phe4,glycinol5)enkephalin (DAMGO) on intestinal mucus secretion were investigated. The experiments were conducted with isolated perfused rat jejunum. Mucus secretion under the influence of beta-casomorphins and opioid neuropeptides administered intraluminally or intra-arterially was evaluated using an ELISA for rat intestinal mucus. Luminal administration of beta-casomorphin-7 (1.2 x 10(-4) mol/L) provoked a mucus discharge (500% of controls) that was inhibited by naloxone, a specific opiate receptor antagonist. Luminal beta-casomorphin-6, -4 and -4NH2 did not modify basal mucus secretion, whereas intra-arterial administration of beta-casomorphin-4 (1.2 x 10(-6) mol/L) induced a mucus discharge. In contrast, intra-arterial administration of the nonopioid peptide beta-casomorphin-3 did not release mucus. Among the opioid neuropeptides, intra-arterial infusion of Met-enkephalin or dynorphin-A did not provoke mucus secretion. In contrast, beta-endorphin (1.2 x 10(-8) to 1.2 x 10(-6) mol/L) induced a dose-dependent release of mucus (maximal response at 500% of controls). DAMGO (1.2 x 10(-6) mol/L), a mu-receptor agonist, also evoked a potent mucus discharge. Our findings suggest that mu-opioid neuropeptides, as well as beta-casomorphins after absorption, modulate intestinal mucus discharge. Milk opioid-derived peptides may thus be involved in defense against noxious agents and could have dietary and health applications.

Melanoma targeting with alpha-melanocyte stimulating hormone analogs labeled with fac-[99mTc(CO)3]+: effect of cyclization on tumor-seeking properties.

Science.gov (United States)

Raposinho, Paula D; Xavier, Catarina; Correia, João D G; Falcão, Soraia; Gomes, Paula; Santos, Isabel

2008-03-01

Early detection of primary melanoma tumors is essential because there is no effective treatment for metastatic melanoma. Several linear and cyclic radiolabeled alpha-melanocyte stimulating hormone (alpha-MSH) analogs have been proposed to target the melanocortin type 1 receptor (MC1R) overexpressed in melanoma. The compact structure of a rhenium-cyclized alpha-MSH analog (Re-CCMSH) significantly enhanced its in vivo tumor uptake and retention. Melanotan II (MT-II), a cyclic lactam analog of alpha-MSH (Ac-Nle-cyclo[Asp-His-DPhe-Arg-Trp-Lys]-NH2]), is a very potent and stable agonist peptide largely used in the characterization of melanocortin receptors. Taking advantage of the superior biological features associated with the MT-II cyclic peptide, we assessed the effect of lactam-based cyclization on the tumor-seeking properties of alpha-MSH analogs by comparing the pharmacokinetics profile of the 99mTc-labeled cyclic peptide betaAla-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2 with that of the linear analog betaAla-Nle-Asp-His-DPhe-Arg-Trp-Lys-NH2 in melanoma-bearing mice. We have synthesized and coupled the linear and cyclic peptides to a bifunctional chelator containing a pyrazolyl-diamine backbone (pz) through the amino group of betaAla, and the resulting pz-peptide conjugates were reacted with the fac-[99mTc(CO)3]+ moiety. The 99mTc(CO)3-labeled conjugates were obtained in high yield, high specific activity, and high radiochemical purity. The cyclic 99mTc(CO)3-labeled conjugate presents a remarkable internalization (87.1% of receptor-bound tracer and 50.5% of total applied activity, after 6 h at 37 degrees C) and cellular retention (only 24.7% released from the cells after 5 h) in murine melanoma B16F1 cells. A significant tumor uptake and retention was obtained in melanoma-bearing C57BL6 mice for the cyclic radioconjugate [9.26 +/- 0.83 and 11.31 +/- 1.83% ID/g at 1 and 4 h after injection, respectively]. The linear 99mTc(CO)3-pz-peptide presented lower values for

Should We Use PPAR Agonists to Reduce Cardiovascular Risk?

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Jennifer G. Robinson

2008-01-01

Full Text Available Trials of peroxisome proliferator-activated receptor (PPAR agonists have shown mixed results for cardiovascular prevention. Fibrates are PPAR- agonists that act primarily to improve dyslipidemia. Based on low- and high-density lipoprotein cholesterol (LDL and HDL effects, gemfibrozil may be of greater cardiovascular benefit than expected, fenofibrate performed about as expected, and bezafibrate performed worse than expected. Increases in both cardiovascular and noncardiovascular serious adverse events have been observed with some fibrates. Thiazolidinediones (TZDs are PPAR- agonists used to improve impaired glucose metabolism but also influence lipids. Pioglitazone reduces atherosclerotic events in diabetic subjects, but has no net cardiovascular benefit due to increased congestive heart failure risk. Rosiglitazone may increase the risk of atherosclerotic events, and has a net harmful effect on the cardiovascular system when congestive heart failure is included. The primary benefit of TZDs appears to be the prevention of diabetic microvascular complications. Dual PPAR-/ agonists have had unacceptable adverse effects but more selective agents are in development. PPAR- and pan-agonists are also in development. It will be imperative to prove that future PPAR agonists not only prevent atherosclerotic events but also result in a net reduction on total cardiovascular events without significant noncardiovascular adverse effects with long-term use.

Principles of agonist recognition in Cys-loop receptors

DEFF Research Database (Denmark)

Lynagh, Timothy Peter; Pless, Stephan Alexander

2014-01-01

, functional studies, and X-ray crystallography experiments identified the extracellular interface of adjacent subunits as the principal site of agonist binding. The question of how subtle differences at and around agonist-binding sites of different Cys-loop receptors can accommodate transmitters as chemically...

Long-acting β2-agonists in asthma

DEFF Research Database (Denmark)

Jacobson, Glenn A; Raidal, Sharanne; Hostrup, Morten

2018-01-01

Long-acting β2-agonists (LABAs) such as formoterol and salmeterol are used for prolonged bronchodilatation in asthma, usually in combination with inhaled corticosteroids (ICSs). Unexplained paradoxical asthma exacerbations and deaths have been associated with LABAs, particularly when used without...... and effects on BHR, particularly that (S)-enantiomers of β2-agonists may be deleterious to asthma control. LABAs display enantioselective pharmacokinetics and pharmacodynamics. Biological plausibility of the deleterious effects of β2-agonists (S)-enantiomers is provided by in vitro and in vivo studies from...... mechanism in rapid asthma deaths. More effort should therefore be applied to investigating potential enantiospecific effects of LABAs on safety, specifically bronchoprotection. Safety studies directly assessing the effects of LABA (S)-enantiomers on BHR are long overdue....

Improving Multi-Epitope Long Peptide Vaccine Potency by Using a Strategy that Enhances CD4+ T Help in BALB/c Mice.

Directory of Open Access Journals (Sweden)

Haniyeh Ghaffari-Nazari

Full Text Available Peptide-based vaccines are attractive approaches for cancer immunotherapy; but the success of these vaccines in clinical trials have been limited. Our goal is to improve immune responses and anti-tumor effects against a synthetic, multi-epitope, long peptide from rat Her2/neu (rHer2/neu using the help of CD4+ T cells and appropriate adjuvant in a mouse tumor model. Female BALB/c mice were vaccinated with P5+435 multi-epitope long peptide that presents epitopes for cytotoxic T lymphocytes (CTL in combination with a universal Pan DR epitope (PADRE or CpG-oligodeoxynucleotides (CpG-ODNs as a Toll-like receptor agonist adjuvant. The results show that vaccination with the multi-epitope long peptide in combination with the PADRE peptide and CpG-ODN induced expansion of subpopulations of CD4+ and CD8+ cells producing IFN-γ, the average tumor size in the vaccinated mice was less than that of the other groups, and tumor growth was inhibited in 40% of the mice in the vaccinated group. The mean survival time was 82.6 ± 1.25 days in mice vaccinated with P5+435 + CpG+ PADRE. Our results demonstrate that inclusion of PADRE and CpG with the peptide vaccine enhanced significant tumor specific-immune responses in vaccinated mice.

A facile and sensitive peptide-modulating graphene oxide nanoribbon catalytic nanoplasmon analytical platform for human chorionic gonadotropin.

Science.gov (United States)

Liang, Aihui; Li, Chongning; Li, Dan; Luo, Yanghe; Wen, Guiqing; Jiang, Zhiliang

2017-01-01

The nanogold reaction between HAuCl 4 and citrate is very slow, and the catalyst graphene oxide nanoribbon (GONR) enhanced the nanoreaction greatly to produce gold nanoparticles (AuNPs) that exhibited strong surface plasmon resonance (SPR) absorption (Abs) at 550 nm and resonance Rayleigh scattering (RRS) at 550 nm. Upon addition of the peptide of human chorionic gonadotropin (hCG), the peptide could adsorb on the GONR surface, which inhibited the catalysis. When hCG was added, peptides were separated from the GONR surface due to the formation of stable peptide-hCG complex, which led to the activation of GONR catalytic effect. With the increase in hCG concentration, the RRS and Abs signal enhanced linearly. The enhanced RRS value showed a good linear relationship with hCG concentration in the range of 0.2-20 ng/mL, with a detection limit of 70 pg/mL. Accordingly, two new GONR catalytic RRS/Abs methods were established for detecting hCG in serum samples.

Small-molecule AT2 receptor agonists

DEFF Research Database (Denmark)

Hallberg, Mathias; Sumners, Colin; Steckelings, U Muscha

2018-01-01

The discovery of the first selective, small-molecule ATR receptor (AT2R) agonist compound 21 (C21) (8) that is now extensively studied in a large variety of in vitro and in vivo models is described. The sulfonylcarbamate derivative 8, encompassing a phenylthiofen scaffold is the drug-like agonist...... with the highest affinity for the AT2R reported to date (Ki = 0.4 nM). Structure-activity relationships (SAR), regarding different biaryl scaffolds and functional groups attached to these scaffolds and with a particular focus on the impact of various para substituents displacing the methylene imidazole group of 8......, are discussed. Furthermore, the consequences of migration of the methylene imidazole group and presumed structural requirements for ligands that are aimed as AT2R agonists (e.g. 8) or AT2R antagonists (e.g. 9), respectively, are briefly addressed. A summary of the pharmacological actions of C21 (8) is also...

Agonist properties of a stable hexapeptide analog of neurotensin, N alpha MeArg-Lys-Pro-Trp-tLeu-Leu (NT1).

Science.gov (United States)

Akunne, H C; Demattos, S B; Whetzel, S Z; Wustrow, D J; Davis, D M; Wise, L D; Cody, W L; Pugsley, T A; Heffner, T G

1995-04-18

The major signal transduction pathway for neurotensin (NT) receptors is the G-protein-dependent stimulation of phospholipase C, leading to the mobilization of intracellular free Ca2+ ([Ca2+]i) and the stimulation of cyclic GMP. We investigated the functional actions of an analog of NT(8-13), N alpha MeArg-Lys-Pro-Trp-tLeu-Leu (NT1), and other NT related analogs by quantitative measurement of the cytosolic free Ca2+ concentration in HT-29 (human colonic adenocarcinoma) cells using the Ca(2+)-sensitive dye fura-2/AM and by effects on cyclic GMP levels in rat cerebellar slices. The NT receptor binding affinities for these analogs to HT-29 cell membranes and newborn (10-day-old) mouse brain membranes were also investigated. Data obtained from HT-29 cell and mouse brain membrane preparations showed saturable single high-affinity sites and binding densities (Bmax) of 130.2 and 87.5 fmol/mg protein, respectively. The respective KD values were 0.47 and 0.39 nM, and the Hill coefficients were 0.99 and 0.92. The low-affinity levocabastine-sensitive site was not present (K1 > 10,000) in either membrane preparation. Although the correlation of binding between HT-29 cell membranes and mouse brain membranes was quite significant (r = 0.92), some of the reference agents had lower binding affinities in the HT-29 cell membranes. The metabolically stable compound NT1 plus other NT analogs and related peptides [NT, NT(8-13), xenopsin, neuromedin N, NT(9-13), kinetensin and (D-Trp11)-NT] increased intracellular Ca2+ levels in HT-29 cells, indicating NT receptor agonist properties. The effect of NT1 in mobilizing [Ca2+]i blocked by SR 48692, a non-peptide NT antagonist. Receptor binding affinities of NT analogs to HT-29 cell membranes were positively correlated with potencies for mobilizing intracellular calcium in the same cells. In addition, NT1 increased cyclic GMP levels in rat cerebellar slices, confirming the latter findings of its NT agonist action. These results substantiate

Peptides and Anti-peptide Antibodies for Small and Medium Scale Peptide and Anti-peptide Affinity Microarrays: Antigenic Peptide Selection, Immobilization, and Processing.

Science.gov (United States)

Zhang, Fan; Briones, Andrea; Soloviev, Mikhail

2016-01-01

This chapter describes the principles of selection of antigenic peptides for the development of anti-peptide antibodies for use in microarray-based multiplex affinity assays and also with mass-spectrometry detection. The methods described here are mostly applicable to small to medium scale arrays. Although the same principles of peptide selection would be suitable for larger scale arrays (with 100+ features) the actual informatics software and printing methods may well be different. Because of the sheer number of proteins/peptides to be processed and analyzed dedicated software capable of processing all the proteins and an enterprise level array robotics may be necessary for larger scale efforts. This report aims to provide practical advice to those who develop or use arrays with up to ~100 different peptide or protein features.

Long-acting beta(2)-agonists in management of childhood asthma

DEFF Research Database (Denmark)

Bisgaard, H

2000-01-01

This review assesses the evidence regarding the use of long-acting beta(2)-agonists in the management of pediatric asthma. Thirty double-blind, randomized, controlled trials on the effects of formoterol and salmeterol on lung function in asthmatic children were identified. Single doses of inhaled......, long-acting beta(2)-agonists provide effective bronchodilatation and bronchoprotection when used as intermittent, single-dose treatment of asthma in children, but not when used as regular treatment. Future studies should examine the positioning of long-acting beta(2)-agonists as an "as needed" rescue...... medication instead of short-acting beta(2)-agonists for pediatric asthma management....

Therapeutic peptides for cancer therapy. Part II - cell cycle inhibitory peptides and apoptosis-inducing peptides.

Science.gov (United States)

Raucher, Drazen; Moktan, Shama; Massodi, Iqbal; Bidwell, Gene L

2009-10-01

Therapeutic peptides have great potential as anticancer agents owing to their ease of rational design and target specificity. However, their utility in vivo is limited by low stability and poor tumor penetration. The authors review the development of peptide inhibitors with potential for cancer therapy. Peptides that arrest the cell cycle by mimicking CDK inhibitors or induce apoptosis directly are discussed. The authors searched Medline for articles concerning the development of therapeutic peptides and their delivery. Inhibition of cancer cell proliferation directly using peptides that arrest the cell cycle or induce apoptosis is a promising strategy. Peptides can be designed that interact very specifically with cyclins and/or cyclin-dependent kinases and with members of apoptotic cascades. Use of these peptides is not limited by their design, as a rational approach to peptide design is much less challenging than the design of small molecule inhibitors of specific protein-protein interactions. However, the limitations of peptide therapy lie in the poor pharmacokinetic properties of these large, often charged molecules. Therefore, overcoming the drug delivery hurdles could open the door for effective peptide therapy, thus making an entirely new class of molecules useful as anticancer drugs.

A novel electrochemical sensor for the analysis of β-agonists: The poly(acid chrome blue K)/graphene oxide-nafion/glassy carbon electrode

Energy Technology Data Exchange (ETDEWEB)

Lin, Xiaoyun [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047 (China); Ni, Yongnian, E-mail: ynni@ncu.edu.cn [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047 (China); Department of Chemistry, Nanchang University, Nanchang 330031 (China); Kokot, Serge, E-mail: s.kokot@qut.edu.au [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane 4001 (Australia)

2013-09-15

Graphical abstract: A new modified electrode was constructed by the electro-polymerization of acid chrome blue K (ACBK) at a graphene-nafion modified glassy carbon electrode (GCE). The novel electrode was successfully employed for the analysis of eight β-agonist analytes with high sensitivity. -- Highlights: • Construction of the poly-ACBK/graphene-nafion/GCE. •The modified electrode showed high sensitivity for the analysis of the β-agonists. • A novel method was successfully developed for the analysis of clenbuterol in pork. • Research provided a new method of constructing electrodes for biological analysis. -- Abstract: A novel modified electrode was constructed by the electro-polymerization of 4,5-dihydroxy-3-[(2-hydroxy-5-sulfophenyl)azo]-2,7-naphthalenedisulfonic acid trisodium salt (acid chrome blue K (ACBK)) at a graphene oxide (GO)-nafion modified glassy carbon electrode (GCE). The characterization of an electrochemically synthesized poly-ACBK/GO-nafion film was investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), atomic force microscopy (AFM) and scanning electron microscopy (SEM) techniques, and the results were interpreted and compared at each stage of the electrode construction. Electrochemical oxidation of eight β-agonists – clenbuterol, salbutamol, terbutaline, ractopamine, dopamine, dobutamine, adrenaline, and isoprenaline, was investigated by CV at the different electrodes. At the poly-ACBK/GO-nafion/GCE, the linear sweep voltammetry peak currents of the eight β-agonists increased linearly with their concentrations in the range of 1.0–36.0 ng mL{sup −1}, respectively, and their corresponding limits of detection (LODs) were within the 0.58–1.46 ng mL{sup −1} range. This electrode showed satisfactory reproducibility and stability, and was used successfully for the quantitative analysis of clenbuterol in pork samples.

Trial Watch: Toll-like receptor agonists for cancer therapy.

Science.gov (United States)

Vacchelli, Erika; Eggermont, Alexander; Sautès-Fridman, Catherine; Galon, Jérôme; Zitvogel, Laurence; Kroemer, Guido; Galluzzi, Lorenzo

2013-08-01

Toll-like receptors (TLRs) have long been known for their ability to initiate innate immune responses upon exposure to conserved microbial components such as lipopolysaccharide (LPS) and double-stranded RNA. More recently, this family of pattern recognition receptors has been attributed a critical role in the elicitation of anticancer immune responses, raising interest in the development of immunochemotherapeutic regimens based on natural or synthetic TLR agonists. In spite of such an intense wave of preclinical and clinical investigation, only three TLR agonists are currently licensed by FDA for use in cancer patients: bacillus Calmette-Guérin (BCG), an attenuated strain of Mycobacterium bovis that operates as a mixed TLR2/TLR4 agonist; monophosphoryl lipid A (MPL), a derivative of Salmonella minnesota that functions as a potent agonist of TLR4; and imiquimod, a synthetic imidazoquinoline that activates TLR7. One year ago, in the August and September issues of OncoImmunology , we described the main biological features of TLRs and discussed the progress of clinical studies evaluating the safety and therapeutic potential of TLR agonists in cancer patients. Here, we summarize the latest developments in this exciting area of research, focusing on preclinical studies that have been published during the last 13 mo and clinical trials launched in the same period to investigate the antineoplastic activity of TLR agonists.

ArrayPitope: Automated Analysis of Amino Acid Substitutions for Peptide Microarray-Based Antibody Epitope Mapping

DEFF Research Database (Denmark)

Hansen, Christian Skjødt; Østerbye, Thomas; Marcatili, Paolo

2017-01-01

and characterization of linear B cell epitopes. Using exhaustive amino acid substitution analysis of peptides originating from target antigens, these microarrays can be used to address the specificity of polyclonal antibodies raised against such antigens containing hundreds of epitopes. However, the interpretation....... The application takes as input quantitative peptide data of fully or partially substituted overlapping peptides from a given antigen sequence and identifies epitope residues (residues that are significantly affected by substitutions) and visualize the selectivity towards each residue by sequence logo plots...

Ascorbic acid enables reversible dopamine receptor 3H-agonist binding

International Nuclear Information System (INIS)

Leff, S.; Sibley, D.R.; Hamblin, M.; Creese, I.

1981-01-01

The effects of ascorbic acid on dopaminergic 3 H-agonist receptor binding were studied in membrane homogenates of bovine anterior pituitary and caudate, and rat striatum. In all tissues virtually no stereospecific binding (defined using 1uM (+)butaclamol) of the 3 H-agonists N-propylnorapomorphine (NPA), apomorphine, or dopamine could be demonstrated in the absence of ascorbic acid. Although levels of total 3 H-agonist binding were three to five times greater in the absence than in the presence of 0.1% ascorbic acid, the increased binding was entirely non-stereospecific. Greater amounts of dopamine-inhibitable 3 H-NPA binding could be demonstrated in the absence of 0.1% ascorbic acid, but this measure of ''specific binding'' was demonstrated not to represent dopamine receptor binding since several other catecholamines and catechol were equipotent with dopamine and more potent than the dopamine agonist (+/-)amino-6,7-dihydroxy-1,2,3,4-tetrahydronapthalene (ADTN) in inhibiting this binding. High levels of dopamine-displaceable 3 H-agonist binding were detected in fresh and boiled homogenates of cerebellum, an area of brain which receives no dopaminergic innervation, further demonstrating the non-specific nature of 3 H-agonist binding in the absence of ascorbic acid. These studies emphasize that under typical assay conditions ascorbic acid is required in order to demonstrate reversible and specific 3 H-agonist binding to dopamine receptors

Agonist-induced affinity alterations of a central nervous system. cap alpha. -bungarotoxin receptor

Energy Technology Data Exchange (ETDEWEB)

Lukas, R.J.; Bennett, E.L.

1979-01-01

The ability of cholinergic agonists to block the specific interaction of ..cap alpha..-bungarotoxin (..cap alpha..-Bgt) with membrane-bound sites derived from rat brain is enhanced when membranes are preincubated with agonist. Thus, pretreatment of ..cap alpha..-Bgt receptors with agonist (but not antagonist) causes transformation of sites to a high-affinity form toward agonist. This change in receptor state occurs with a half-time on the order of minutes, and is fully reversible on dilution of agonist. The results are consistent with the identity of ..cap alpha..-Bgt binding sites as true central nicotinic acetylcholine receptors. Furthermore, this agonist-induced alteration in receptor state may represent an in vitro correlate of physiological desensitization. As determined from the effects of agonist on toxin binding isotherms, and on the rate of toxin binding to specific sites, agonist inhibition of toxin binding to the high-affinity state is non-competitive. This result suggests that there may exist discrete toxin-binding and agonist-binding sites on central toxin receptors.

Angiotensin II Type 2 Receptor Agonist Experts Sustained Neuroprotective Effects In Aged Rats

DEFF Research Database (Denmark)

Sumners, Colin; Isenberg, Jacob; Harmel, Allison

2016-01-01

OBJECTIVE: The renin angiotensin system is a promising target for stroke neuroprotection and therapy through activation of angiotensin type II receptors (AT2R). The selective non-peptide AT2R agonist, Compound 21 (C21), has been shown to exhibit neuroprotection and improve stroke outcomes...... in preclinical studies, effects that likely involve neurotropic actions. However, these beneficial actions of C21 have not been demonstrated to occur beyond 1 week post stroke. The objective of this study was to determine if systemic administration of C21 would exert sustained neuroprotective effects in aged...... min), 24 h, and 48 h after stroke. Infarct size was assessed by magnetic resonance imaging at 21 days post MCAO. Animals received blinded neurological exams at 4 h, 24 h, 72 h, 7d, 14d, and 21d post-MCAO. RESULTS: Systemic treatment with C21 after stroke significantly improved neurological function...

Molecular architecture with carbohydrate functionalized β-peptides adopting 314-helical conformation

Directory of Open Access Journals (Sweden)

Nitin J. Pawar

2014-04-01

Full Text Available Carbohydrate recognition is essential in cellular interactions and biological processes. It is characterized by structural diversity, multivalency and cooperative effects. To evaluate carbohydrate interaction and recognition, the structurally defined attachment of sugar units to a rigid template is highly desired. β-Peptide helices offer conformationally stable templates for the linear presentation of sugar units in defined distances. The synthesis and β-peptide incorporation of sugar-β-amino acids are described providing the saccharide units as amino acid side chain. The respective sugar-β-amino acids are accessible by Michael addition of ammonia to sugar units derivatized as α,β-unsaturated esters. Three sugar units were incorporated in β-peptide oligomers varying the sugar (glucose, galactose, xylose and sugar protecting groups. The influence of sugar units and the configuration of sugar-β-amino acids on β-peptide secondary structure were investigated by CD spectroscopy.

Oxidative diversification of amino acids and peptides by small-molecule iron catalysis.

Science.gov (United States)

Osberger, Thomas J; Rogness, Donald C; Kohrt, Jeffrey T; Stepan, Antonia F; White, M Christina

2016-09-08

Secondary metabolites synthesized by non-ribosomal peptide synthetases display diverse and complex topologies and possess a range of biological activities. Much of this diversity derives from a synthetic strategy that entails pre- and post-assembly oxidation of both the chiral amino acid building blocks and the assembled peptide scaffolds. The vancomycin biosynthetic pathway is an excellent example of the range of oxidative transformations that can be performed by the iron-containing enzymes involved in its biosynthesis. However, because of the challenges associated with using such oxidative enzymes to carry out chemical transformations in vitro, chemical syntheses guided by these principles have not been fully realized in the laboratory. Here we report that two small-molecule iron catalysts are capable of facilitating the targeted C-H oxidative modification of amino acids and peptides with preservation of α-centre chirality. Oxidation of proline to 5-hydroxyproline furnishes a versatile intermediate that can be transformed to rigid arylated derivatives or flexible linear carboxylic acids, alcohols, olefins and amines in both monomer and peptide settings. The value of this C-H oxidation strategy is demonstrated in its capacity for generating diversity: four 'chiral pool' amino acids are transformed to twenty-one chiral unnatural amino acids representing seven distinct functional group arrays; late-stage C-H functionalizations of a single proline-containing tripeptide furnish eight tripeptides, each having different unnatural amino acids. Additionally, a macrocyclic peptide containing a proline turn element is transformed via late-stage C-H oxidation to one containing a linear unnatural amino acid.

Engineering an Affinity-Enhanced Peptide through Optimization of Cyclization Chemistry.

Science.gov (United States)

Ngambenjawong, Chayanon; Pineda, Julio Marco B; Pun, Suzie H

2016-12-21

Peptide cyclization is a strategy used to improve stability and activity of peptides. The most commonly used cyclization method is disulfide bridge formation of cysteine-containing peptides, as is typically found in nature. Over the years, an increasing number of alternative chemistries for peptide cyclization with improved efficiency, kinetics, orthogonality, and stability have been reported. However, there has been less appreciation for the opportunity to fine-tune peptide activity via the diverse chemical entities introduced at the site of linkage by different cyclization strategies. Here, we demonstrate how cyclization optimization of an M2 "anti-inflammatory" macrophage-binding peptide (M2pep) resulted in a significant increase in binding affinity of the optimized analog to M2 macrophages while maintaining binding selectivity compared to M1 "pro-inflammatory" macrophages. In this study, we report synthesis and evaluation of four cyclic M2pep(RY) analogs with diverse cyclization strategies: (1) Asp-[amide]-Lys, (2) azido-Lys-[triazole(copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC))]-propargyl-Gly, (3) Cys-[decafluorobiphenyl (DFBP)]-Cys, and (4) Cys-[decafluorobiphenyl sulfone (DFS)]-Cys, whereby the chemical entity or linker at the linkage site is shown in the square bracket and is between the residues involved in cyclization. These peptides are compared to a disulfide-cyclized M2pep(RY) that we previously reported as a serum-stable, affinity-enhanced analog to the original linear M2pep. DFBP-cyclized M2pep(RY) exhibits the highest binding activity to M2 macrophages with apparent dissociation constant (K D ) about 2.03 μM compared to 36.3 μM for the original disulfide-cyclized M2pep(RY) and 220 μM for the original linear peptide. DFS-cyclized M2pep(RY) also binds more strongly than the original cyclized analog, whereas amide- and triazole-cyclized M2pep(RY) analogs bind less strongly. We verified that DFBP alone has negligible binding to M2

Peptides, polypeptides and peptide-polymer hybrids as nucleic acid carriers.

Science.gov (United States)

Ahmed, Marya

2017-10-24

Cell penetrating peptides (CPPs), and protein transduction domains (PTDs) of viruses and other natural proteins serve as a template for the development of efficient peptide based gene delivery vectors. PTDs are sequences of acidic or basic amphipathic amino acids, with superior membrane trespassing efficacies. Gene delivery vectors derived from these natural, cationic and cationic amphipathic peptides, however, offer little flexibility in tailoring the physicochemical properties of single chain peptide based systems. Owing to significant advances in the field of peptide chemistry, synthetic mimics of natural peptides are often prepared and have been evaluated for their gene expression, as a function of amino acid functionalities, architecture and net cationic content of peptide chains. Moreover, chimeric single polypeptide chains are prepared by a combination of multiple small natural or synthetic peptides, which imparts distinct physiological properties to peptide based gene delivery therapeutics. In order to obtain multivalency and improve the gene delivery efficacies of low molecular weight cationic peptides, bioactive peptides are often incorporated into a polymeric architecture to obtain novel 'polymer-peptide hybrids' with improved gene delivery efficacies. Peptide modified polymers prepared by physical or chemical modifications exhibit enhanced endosomal escape, stimuli responsive degradation and targeting efficacies, as a function of physicochemical and biological activities of peptides attached onto a polymeric scaffold. The focus of this review is to provide comprehensive and step-wise progress in major natural and synthetic peptides, chimeric polypeptides, and peptide-polymer hybrids for nucleic acid delivery applications.

Structure-activity relationship of linear peptide Bu-His-DPhe-Arg-Trp-Gly-NH(2) at the human melanocortin-1 and -4 receptors: histidine substitution.

Science.gov (United States)

Cheung, Adrian Wai-Hing; Danho, Waleed; Swistok, Joseph; Qi, Lida; Kurylko, Grazyna; Rowan, Karen; Yeon, Mitch; Franco, Lucia; Chu, Xin-Jie; Chen, Li; Yagaloff, Keith

2003-01-06

Systematic substitution of His(6) residue using non-selective hMC4R pentapeptide agonist (Bu-His(6)-DPhe(7)-Arg(8)-Trp(9)-Gly(10)-NH(2)) as the template led to the identification of Bu-Atc(6)(2-aminotetraline-2-carboxylic acid)-DPhe(7)-Arg(8)-Trp(9)-Gly(10)-NH(2) which showed moderate selectivity towards hMC4R over hMC1R. Further SAR studies resulted in the discovery of Penta-5-BrAtc(6)-DPhe(7)-Arg(8)-Trp(9)-Gly(10)-NH(2) and Penta-5-Me(2)NAtc(6)-DPhe(7)-Arg(8)-Trp(9)-Gly(10)-NH(2) which are potent hMC4R agonists and are inactive in hMC1R, hMC3R and hMC5R agonist assays.

Identification of putative agouti-related protein(87-132)-melanocortin-4 receptor interactions by homology molecular modeling and validation using chimeric peptide ligands.

Science.gov (United States)

Wilczynski, Andrzej; Wang, Xiang S; Joseph, Christine G; Xiang, Zhimin; Bauzo, Rayna M; Scott, Joseph W; Sorensen, Nicholas B; Shaw, Amanda M; Millard, William J; Richards, Nigel G; Haskell-Luevano, Carrie

2004-04-22

Agouti-related protein (AGRP) is one of only two naturally known antagonists of G-protein-coupled receptors (GPCRs) identified to date. Specifically, AGRP antagonizes the brain melanocortin-3 and -4 receptors involved in energy homeostasis. Alpha-melanocyte stimulating hormone (alpha-MSH) is one of the known endogenous agonists for these melanocortin receptors. Insight into putative interactions between the antagonist AGRP amino acids with the melanocortin-4 receptor (MC4R) may be important for the design of unique ligands for the treatment of obesity related diseases and is currently lacking in the literature. A three-dimensional homology molecular model of the mouse MC4 receptor complex with the hAGRP(87-132) ligand docked into the receptor has been developed to identify putative antagonist ligand-receptor interactions. Key putative AGRP-MC4R interactions include the Arg111 of hAGRP(87-132) interacting in a negatively charged pocket located in a cavity formed by transmembrane spanning (TM) helices 1, 2, 3, and 7, capped by the acidic first extracellular loop (EL1) and specifically with the conserved melanocortin receptor residues mMC4R Glu92 (TM2), mMC4R Asp114 (TM3), and mMC4R Asp118 (TM3). Additionally, Phe112 and Phe113 of hAGRP(87-132) putatively interact with an aromatic hydrophobic pocket formed by the mMC4 receptor residues Phe176 (TM4), Phe193 (TM5), Phe253 (TM6), and Phe254 (TM6). To validate the AGRP-mMC4R model complex presented herein from a ligand perspective, we generated nine chimeric peptide ligands based on a modified antagonist template of the hAGRP(109-118) (Tyr-c[Asp-Arg-Phe-Phe-Asn-Ala-Phe-Dpr]-Tyr-NH(2)). In these chimeric ligands, the antagonist AGRP Arg-Phe-Phe residues were replaced by the melanocortin agonist His/D-Phe-Arg-Trp amino acids. These peptides resulted in agonist activity at the mouse melanocortin receptors (mMC1R and mMC3-5Rs). The most notable results include the identification of a novel subnanomolar melanocortin peptide

Hormones and β-Agonists

NARCIS (Netherlands)

Ginkel, van L.A.; Bovee, T.F.H.; Blokland, M.H.; Sterk, S.S.; Smits, N.G.E.; Pleadin, Jelka; Vulić, Ana

2016-01-01

This chapter provides some updated information on contemporary methods for hormone and β-agonist analyses. It deals with the classical approaches for the effective detection and identification of exogenous hormones. The chapter examines specific problems related to control strategies for natural

Lumazine Peptides from the Marine-Derived Fungus Aspergillus terreus

Directory of Open Access Journals (Sweden)

Minjung You

2015-03-01

Full Text Available Terrelumamides A (1 and B (2, two new lumazine-containing peptides, were isolated from the culture broth of the marine-derived fungus Aspergillus terreus. From the results of combined spectroscopic and chemical analyses, the structures of these compounds were determined to be linear assemblies of 1-methyllumazine-6-carboxylic acid, an amino acid residue and anthranilic acid methyl ester connected by peptide bonds. These new compounds exhibited pharmacological activity by improving insulin sensitivity, which was evaluated in an adipogenesis model using human bone marrow mesenchymal stem cells. In addition, the compounds exhibited fluorescence changes upon binding to DNA, demonstrating their potential applications to DNA sequence recognition.

Synthesis of water-soluble scaffolds for peptide cyclization, labeling, and ligation

NARCIS (Netherlands)

Smeenk, L.E.J.; Dailly, N.; Hiemstra, H.; van Maarseveen, J.H.; Timmerman, P.

2012-01-01

The synthesis and applications of water-soluble scaffolds that conformationally constrain side chain unprotected linear peptides containing two cysteines are described. These scaffolds contain a functionality with orthogonal reactivity to be used for labeling and ligation. This is illustrated by the

Novel antimicrobial peptides isolated from the venom of wild bees

Czech Academy of Sciences Publication Activity Database

Čeřovský, Václav; Monincová, Lenka; Slaninová, Jiřina; Fučík, Vladimír; Borovičková, Lenka; Hovorka, Oldřich; Voburka, Zdeněk; Cvačka, Josef; Bednárová, Lucie; Buděšínský, Miloš; Straka, J.

2009-01-01

Roč. 276, Suppl. 1 (2009), s. 106-106 ISSN 1742-464X. [FEBS Congress /34/. 04.07.2009-09.07.2009, Praha] Institutional research plan: CEZ:AV0Z40550506 Keywords : linear cationic alpha-helical antimicrobial peptides * Edman degradation * mass spectrometry Subject RIV: CC - Organic Chemistry

Characterization of linear mimetic peptides of Interleukin-22 from dissection of protein interfaces.

Science.gov (United States)

La Manna, Sara; Scognamiglio, Pasqualina Liana; Di Natale, Concetta; Leone, Marilisa; Mercurio, Flavia Anna; Malfitano, Anna Maria; Cianfarani, Francesca; Madonna, Stefania; Caravella, Sergio; Albanesi, Cristina; Novellino, Ettore; Marasco, Daniela

2017-07-01

Interleukin-22 (IL-22) belongs to the family of IL-10 cytokines and is involved in a wide number of human diseases, including inflammatory disorders and cancer pathology. The ligand-receptor complex IL-22/IL-22R plays a key role in several pathways especially in the regulation and resolution of immune responses. The identification of novel compounds able to modulate IL-22/IL-22R complex could open the route to new therapeutic strategies in multiple human diseases. In this study, we designed and characterized IL-22 derived peptides at protein interface regions: several sequences revealed able to interfere with the protein complex with IC 50 in the micromolar range as evaluated through Surface Plasmon Resonance (SPR) experiments. Their conformational characterization was carried out through Circular Dichroism (CD) and Nuclear Magnetic Resonance (NMR) spectroscopies, shedding new light into the features of IL-22 fragments and on structural determinants of IL-22/IL-22R1 recognition. Finally, several peptides were tested on human keratinocyte cultures for evaluating their ability to mimic the activation of molecular pathways downstream to IL-22R in response to IL-22 binding. Copyright © 2017 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

Determination of Disulfide Bond Connectivity of Cysteine-rich Peptide IpTx{sub a}

Energy Technology Data Exchange (ETDEWEB)

Lee, Chul Won; Kim, Jim Il [Chonnam National Univ., Gwangju (Korea, Republic of); Sato, Kazuki [Fukuoka Women' s Univ., Fukuoka (Japan)

2013-06-15

Cysteine-rich peptides stabilized by intramolecular disulfide bonds have often been isolated from venoms of microbes, animals and plants. These peptides typically have much higher stability and improved biopharmaceutical properties compared to their linear counterparts. Therefore the correct disulfide bond formation of small proteins and peptides has been extensively studied for a better understanding of their folding mechanism and achieving efficient generation of the naturally occurring biologically active product. Imperatoxin A (IpTx{sub a}), a peptide toxin containing 6 cysteine residues, was isolated from the venom of scorpion Pandinus imperator, selectively binds the ryanodine receptors and activates Ca{sup 2+} release from sarcoplasmic reticulum (SR). IpTx{sub a} increases the binding of ryanodine to ryanodine receptors (RyRs) and encourages reconstituted single channel to induce subconductance states.

Structural pattern matching of nonribosomal peptides

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Leclère Valérie

2009-03-01

Full Text Available Abstract Background Nonribosomal peptides (NRPs, bioactive secondary metabolites produced by many microorganisms, show a broad range of important biological activities (e.g. antibiotics, immunosuppressants, antitumor agents. NRPs are mainly composed of amino acids but their primary structure is not always linear and can contain cycles or branchings. Furthermore, there are several hundred different monomers that can be incorporated into NRPs. The NORINE database, the first resource entirely dedicated to NRPs, currently stores more than 700 NRPs annotated with their monomeric peptide structure encoded by undirected labeled graphs. This opens a way to a systematic analysis of structural patterns occurring in NRPs. Such studies can investigate the functional role of some monomeric chains, or analyse NRPs that have been computationally predicted from the synthetase protein sequence. A basic operation in such analyses is the search for a given structural pattern in the database. Results We developed an efficient method that allows for a quick search for a structural pattern in the NORINE database. The method identifies all peptides containing a pattern substructure of a given size. This amounts to solving a variant of the maximum common subgraph problem on pattern and peptide graphs, which is done by computing cliques in an appropriate compatibility graph. Conclusion The method has been incorporated into the NORINE database, available at http://bioinfo.lifl.fr/norine. Less than one second is needed to search for a pattern in the entire database.

Glucagon-Like Peptide-1 and Its Class B G Protein–Coupled Receptors: A Long March to Therapeutic Successes

Science.gov (United States)

de Graaf, Chris; Donnelly, Dan; Wootten, Denise; Lau, Jesper; Sexton, Patrick M.; Miller, Laurence J.; Ahn, Jung-Mo; Liao, Jiayu; Fletcher, Madeleine M.; Brown, Alastair J. H.; Zhou, Caihong; Deng, Jiejie; Wang, Ming-Wei

2016-01-01

The glucagon-like peptide (GLP)-1 receptor (GLP-1R) is a class B G protein–coupled receptor (GPCR) that mediates the action of GLP-1, a peptide hormone secreted from three major tissues in humans, enteroendocrine L cells in the distal intestine, α cells in the pancreas, and the central nervous system, which exerts important actions useful in the management of type 2 diabetes mellitus and obesity, including glucose homeostasis and regulation of gastric motility and food intake. Peptidic analogs of GLP-1 have been successfully developed with enhanced bioavailability and pharmacological activity. Physiologic and biochemical studies with truncated, chimeric, and mutated peptides and GLP-1R variants, together with ligand-bound crystal structures of the extracellular domain and the first three-dimensional structures of the 7-helical transmembrane domain of class B GPCRs, have provided the basis for a two-domain–binding mechanism of GLP-1 with its cognate receptor. Although efforts in discovering therapeutically viable nonpeptidic GLP-1R agonists have been hampered, small-molecule modulators offer complementary chemical tools to peptide analogs to investigate ligand-directed biased cellular signaling of GLP-1R. The integrated pharmacological and structural information of different GLP-1 analogs and homologous receptors give new insights into the molecular determinants of GLP-1R ligand selectivity and functional activity, thereby providing novel opportunities in the design and development of more efficacious agents to treat metabolic disorders. PMID:27630114

Effect of GLP-1 Receptor Agonist Treatment on Body weight in Obese Antipsychotic-treated Patients with Schizophrenia

DEFF Research Database (Denmark)

Ishøy, Pelle L; Knop, Filip K; Broberg, Brian V

2017-01-01

AIMS: Schizophrenia is associated with cardiovascular co-morbidity and a reduced life-expectancy of up to 20 years. Antipsychotics are dopamine D2 receptor antagonists and the standard of medical care in schizophrenia, but the drugs are associated with severe metabolic side effects like obesity...... and diabetes. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are registered for treatment of both obesity and type 2 diabetes. We investigated metabolic effects of the GLP-1RA, exenatide once-weekly, in non-diabetic, antipsychotic-treated, obese patients with schizophrenia. MATERIAL AND METHODS......: Antipsychotic-treated, obese, non-diabetic, schizophrenia spectrum patients were randomized to double-blinded adjunctive treatment with once-weekly subcutaneous exenatide (n = 23) or placebo (n = 22) injections for three months. The primary outcome was body weight loss after treatment and repeated measures...

Peptide ligands specific to the oxidized form of escherichia coli thioredoxin.

Energy Technology Data Exchange (ETDEWEB)

Scholle, M. D.; Banach, B. S.; Hamdan, S. M.; Richardson, C. C.; Kay, B. K.; Biosciences Division; Amunix, Inc.; Univ. of Illinois at Chicago; Harvard Medical School

2008-11-01

Thioredoxin (Trx) is a highly conserved redox protein involved in several essential cellular processes. In this study, our goal was to isolate peptide ligands to Escherichia coli Trx that mimic protein-protein interactions, specifically the T7 polymerase-Trx interaction. To do this, we subjected Trx to affinity selection against a panel of linear and cysteine-constrained peptides using M13 phage display. A novel cyclized conserved peptide sequence, with a motif of C(D/N/S/T/G)D(S/T)-hydrophobic-C-X-hydrophobic-P, was isolated to Trx. These peptides bound specifically to the E. coli Trx when compared to the human and spirulina homologs. An alanine substitution of the active site cysteines (CGPC) resulted in a significant loss of peptide binding affinity to the Cys-32 mutant. The peptides were also characterized in the context of Trx's role as a processivity factor of the T7 DNA polymerase (gp5). As the interaction between gp5 and Trx normally takes place under reducing conditions, which might interfere with the conformation of the disulfide-bridged peptides, we made use of a 22 residue deletion mutant of gp5 in the thioredoxin binding domain (gp5{Delta}22) that bypassed the requirements of reducing conditions to interact with Trx. A competition study revealed that the peptide selectively inhibits the interaction of gp5{Delta}22 with Trx, under oxidizing conditions, with an IC50 of {approx} 10 {micro}M.

Chagas disease-specific antigens: characterization of epitopes in CRA/FRA by synthetic peptide mapping and evaluation by ELISA-peptide assay.

Science.gov (United States)

Bottino, Carolina G; Gomes, Luciano P; Pereira, José B; Coura, José R; Provance, David William; De-Simone, Salvatore G

2013-12-03

The identification of epitopes in proteins recognized by medically relevant antibodies is useful for the development of peptide-based diagnostics and vaccines. In this study, epitopes in the cytoplasmic repetitive antigen (CRA) and flagellar repetitive antigen (FRA) proteins from Trypanosoma cruzi were identified using synthetic peptide techniques and pooled sera from Chagasic patients. The epitopes were further assayed with an ELISA assay based on synthetic peptides. Twenty-two overlapping synthetic peptides representing the coding sequence of the T. cruzi CRA and FRA proteins were assessed by a Spot-synthesis array analysis using sera donated by patients with Chagas disease. Shorter peptides were selected that represented the determined epitopes and synthesized by solid phase synthesis to evaluate the patterns of cross-reactivities and discrimination through an ELISA-diagnostic assay. The peptide Spot-synthesis array successfully identified two IgG antigenic determinants in the CRA protein and four in FRA. Bioinformatics suggested that the CRA antigens were unique to T. cruzi while the FRA antigen showed similarity with sequences present within various proteins from Leishmania sp. Subsequently, shorter peptides representing the CRA-1, CRA-2 and FRA-1 epitopes were synthesized by solid phase synthesis and assayed by an ELISA-diagnostic assay. The CRA antigens gave a high discrimination between Chagasic, Leishmaniasis and T. cruzi-uninfected serum. A sensitivity and specificity of 100% was calculated for CRA. While the FRA antigen showed a slightly lower sensitivity (91.6%), its specificity was only 60%. The epitopes recognized by human anti-T. cruzi antibodies have been precisely located in two biomarkers of T. cruzi, CRA and FRA. The results from screening a panel of patient sera through an ELISA assay based on peptides representing these epitopes strongly suggest that the sequences from CRA would be useful for the development of diagnostic reagents that could

Cathepsin-Mediated Cleavage of Peptides from Peptide Amphiphiles Leads to Enhanced Intracellular Peptide Accumulation

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Acar, Handan [Institute; Department; Samaeekia, Ravand [Institute; Department; Schnorenberg, Mathew R. [Institute; Department; Medical; Sasmal, Dibyendu K. [Institute; Huang, Jun [Institute; Tirrell, Matthew V. [Institute; Institute; LaBelle, James L. [Department

2017-08-24

Peptides synthesized in the likeness of their native interaction domain(s) are natural choices to target protein protein interactions (PPIs) due to their fidelity of orthostatic contact points between binding partners. Despite therapeutic promise, intracellular delivery of biofunctional peptides at concentrations necessary for efficacy remains a formidable challenge. Peptide amphiphiles (PAs) provide a facile method of intracellular delivery and stabilization of bioactive peptides. PAs consisting of biofunctional peptide headgroups linked to hydrophobic alkyl lipid-like tails prevent peptide hydrolysis and proteolysis in circulation, and PA monomers are internalized via endocytosis. However, endocytotic sequestration and steric hindrance from the lipid tail are two major mechanisms that limit PA efficacy to target intracellular PPIs. To address these problems, we have constructed a PA platform consisting of cathepsin-B cleavable PAs in which a selective p53-based inhibitory peptide is cleaved from its lipid tail within endosomes, allowing for intracellular peptide accumulation and extracellular recycling of the lipid moiety. We monitor for cleavage and follow individual PA components in real time using a resonance energy transfer (FRET)-based tracking system. Using this platform, components in real time using a Forster we provide a better understanding and quantification of cellular internalization, trafficking, and endosomal cleavage of PAs and of the ultimate fates of each component.

De novo peptide design and experimental validation of histone methyltransferase inhibitors.

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James Smadbeck

Full Text Available Histones are small proteins critical to the efficient packaging of DNA in the nucleus. DNA–protein complexes, known as nucleosomes, are formed when the DNA winds itself around the surface of the histones. The methylation of histone residues by enhancer of zeste homolog 2 (EZH2 maintains gene repression over successive cell generations. Overexpression of EZH2 can silence important tumor suppressor genes leading to increased invasiveness of many types of cancers. This makes the inhibition of EZH2 an important target in the development of cancer therapeutics. We employed a three-stage computational de novo peptide design method to design inhibitory peptides of EZH2. The method consists of a sequence selection stage and two validation stages for fold specificity and approximate binding affinity. The sequence selection stage consists of an integer linear optimization model that was solved to produce a rank-ordered list of amino acid sequences with increased stability in the bound peptide-EZH2 structure. These sequences were validated through the calculation of the fold specificity and approximate binding affinity of the designed peptides. Here we report the discovery of novel EZH2 inhibitory peptides using the de novo peptide design method. The computationally discovered peptides were experimentally validated in vitro using dose titrations and mechanism of action enzymatic assays. The peptide with the highest in vitro response, SQ037, was validated in nucleo using quantitative mass spectrometry-based proteomics. This peptide had an IC50 of 13.5 mM, demonstrated greater potency as an inhibitor when compared to the native and K27A mutant control peptides, and demonstrated competitive inhibition versus the peptide substrate. Additionally, this peptide demonstrated high specificity to the EZH2 target in comparison to other histone methyltransferases. The validated peptides are the first computationally designed peptides that directly inhibit EZH2

De novo peptide design and experimental validation of histone methyltransferase inhibitors.

Directory of Open Access Journals (Sweden)

James Smadbeck

Full Text Available Histones are small proteins critical to the efficient packaging of DNA in the nucleus. DNA-protein complexes, known as nucleosomes, are formed when the DNA winds itself around the surface of the histones. The methylation of histone residues by enhancer of zeste homolog 2 (EZH2 maintains gene repression over successive cell generations. Overexpression of EZH2 can silence important tumor suppressor genes leading to increased invasiveness of many types of cancers. This makes the inhibition of EZH2 an important target in the development of cancer therapeutics. We employed a three-stage computational de novo peptide design method to design inhibitory peptides of EZH2. The method consists of a sequence selection stage and two validation stages for fold specificity and approximate binding affinity. The sequence selection stage consists of an integer linear optimization model that was solved to produce a rank-ordered list of amino acid sequences with increased stability in the bound peptide-EZH2 structure. These sequences were validated through the calculation of the fold specificity and approximate binding affinity of the designed peptides. Here we report the discovery of novel EZH2 inhibitory peptides using the de novo peptide design method. The computationally discovered peptides were experimentally validated in vitro using dose titrations and mechanism of action enzymatic assays. The peptide with the highest in vitro response, SQ037, was validated in nucleo using quantitative mass spectrometry-based proteomics. This peptide had an IC50 of 13.5 [Formula: see text]M, demonstrated greater potency as an inhibitor when compared to the native and K27A mutant control peptides, and demonstrated competitive inhibition versus the peptide substrate. Additionally, this peptide demonstrated high specificity to the EZH2 target in comparison to other histone methyltransferases. The validated peptides are the first computationally designed peptides that directly

Screening and identification of T helper 1 and linear immunodominant antibody-binding epitopes in spike 1 domain and membrane protein of feline infectious peritonitis virus.

Science.gov (United States)

Takano, Tomomi; Morioka, Hiroyuki; Gomi, Kohji; Tomizawa, Keisuke; Doki, Tomoyoshi; Hohdatsu, Tsutomu

2014-04-01

Feline infectious peritonitis virus (FIP virus: FIPV) causes a fatal disease in wild and domestic cats. The development of an FIP-preventive vaccine requires an antigen that does not induce antibody-dependent enhancement, and T helper (Th)1 activity plays an important role in protect against FIPV infection. In the present study, we identified synthetic peptides including Th1 and a linear immunodominant antibody-binding epitope in the S1 domain and M protein of FIPV. We also identified peptides that strongly induce Th1 activity from those derived from the structural proteins (S, M, and N proteins) of FIPV based on this and previous studies (Satoh et al. [19]). No Th1 epitope-containing peptide was identified in the peptides derived from the S1 domain of type I FIPV. In contrast, 7 Th1 epitope-containing peptides were identified in the S1 domain of type II FIPV, and no linear immunodominant antibody-binding epitope was contained in any of these peptides. Eleven Th1 epitope-containing peptides common to each serotype were identified in the M protein-derived peptides, and 2 peptides (M-11 and M-12) contained the linear immunodominant antibody-binding epitope. Of the peptides derived from the S, M, and N proteins of FIPV, those that induced significantly stronger Th1 activity than that of the FIPV antigen were rescreened, and 4 peptides were identified. When 3 of these peptides (M-9, I-S2-15, and II-S1-24) were selected and administered with CpG-ODNs to SPF cats, M-9 and II-S1-24 induced Th1 activity. Our results may provide important information for the development of a peptide-based vaccine against FIPV infection. Copyright © 2014 Elsevier Ltd. All rights reserved.

Structure-activity studies of RFamide peptides reveal subtype-selective activation of neuropeptide FF1 and FF2 receptors.

Science.gov (United States)

Findeisen, Maria; Rathmann, Daniel; Beck-Sickinger, Annette G

2011-06-06

Selectivity is a major issue in closely related multiligand/multireceptor systems. In this study we investigated the RFamide systems of hNPFF₁R and hNPFF₂R that bind the endogenous peptide hormones NPFF, NPAF, NPVF, and NPSF. By use of a systematic approach, we characterized the role of the C-terminal dipeptide with respect to agonistic properties using synthesized [Xaa 7]NPFF and [Xaa 8]NPFF analogues. We were able to identify only slight differences in potency upon changing the position of Arg 7, as all modifications resulted in identical behavior at the NPFF₁R and NPFF₂R. However, the C-terminal Phe 8 was able to be replaced by Trp or His with only a minor loss in potency at the NPFF₂R relative to the NPFF₁R. Analogues with shorter side chains, such as α-amino-4-guanidino butyric acid ([Agb 7]NPFF) or phenylglycine ([Phg 8]NPFF), decreased efficacy for the NPFF₁ R to 25-31 % of the maximal response, suggesting that these agonist-receptor complexes are more susceptible to structural modifications. In contrast, mutations to the conserved Asp 6.59 residue in the third extracellular loop of both receptors revealed a higher sensitivity toward the hNPFF₂R receptor than toward hNPFF₁R. These data provide new insight into the subtype-specific agonistic activation of the NPFF₁ and NPFF(2) receptors that are necessary for the development of selective agonists. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Binding free energy predictions of farnesoid X receptor (FXR) agonists using a linear interaction energy (LIE) approach with reliability estimation: application to the D3R Grand Challenge 2

Science.gov (United States)

Rifai, Eko Aditya; van Dijk, Marc; Vermeulen, Nico P. E.; Geerke, Daan P.

2018-01-01

Computational protein binding affinity prediction can play an important role in drug research but performing efficient and accurate binding free energy calculations is still challenging. In the context of phase 2 of the Drug Design Data Resource (D3R) Grand Challenge 2 we used our automated eTOX ALLIES approach to apply the (iterative) linear interaction energy (LIE) method and we evaluated its performance in predicting binding affinities for farnesoid X receptor (FXR) agonists. Efficiency was obtained by our pre-calibrated LIE models and molecular dynamics (MD) simulations at the nanosecond scale, while predictive accuracy was obtained for a small subset of compounds. Using our recently introduced reliability estimation metrics, we could classify predictions with higher confidence by featuring an applicability domain (AD) analysis in combination with protein-ligand interaction profiling. The outcomes of and agreement between our AD and interaction-profile analyses to distinguish and rationalize the performance of our predictions highlighted the relevance of sufficiently exploring protein-ligand interactions during training and it demonstrated the possibility to quantitatively and efficiently evaluate if this is achieved by using simulation data only.

Determination of bovine lactoferrin in dairy products by ultra-high performance liquid chromatography–tandem mass spectrometry based on tryptic signature peptides employing an isotope-labeled winged peptide as internal standard

Energy Technology Data Exchange (ETDEWEB)

Zhang, Jingshun [Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou 310051 (China); Lai, Shiyun [Beingmate Research Institute, Beingmate Baby and Child Food Co., Ltd., Hangzhou 310007 (China); Cai, Zengxuan [Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou 310051 (China); Chen, Qi [Beingmate Research Institute, Beingmate Baby and Child Food Co., Ltd., Hangzhou 310007 (China); Huang, Baifen [Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou 310051 (China); Ren, Yiping, E-mail: renyiping@263.net [Zhejiang Provincial Center for Disease Control and Prevention, Hangzhou 310051 (China)

2014-06-01

Highlights: • A UHPLC–MS/MS method for quantification of bovine lactoferrin was developed. • Tryptic fragment LRPVAAEIYGTK was chosen as signature peptide of bovine lactoferrin. • A winged peptide containing isotopically-labeled signature peptide was designed as internal standard. • The method for determining lactoferrin does not discriminate between the different forms of lactoferrin. • Meet the growing demand to quantify bovine lactoferrin in different dairy products. Abstract: A new and sensitive determination method was developed for bovine lactoferrin in dairy products including infant formulas based on the signature peptide by ultra high-performance liquid chromatography and triple-quadrupole tandem mass spectrometry under the multiple reaction monitoring mode. The simple pretreatment procedures included the addition of a winged peptide containing the isotope-labeled signature peptide as internal standard, followed by an enzymatic digestion with trypsin. The signature peptide was chosen and identified from the tryptic hydrolyzates of bovine lactoferrin by ultra high-performance liquid chromatography and quadrupole-time-of-flight tandem mass spectrometry based on sequence database search. Analytes were separated on an ACQUITY UPLC BEH 300 C18 column and monitored by MS/MS in seven minutes. Quantitative result bias due to matrix effect and tryptic efficiency was corrected through the use of synthetic isotope-labeled standards. The limit of detection and limit of quantification were 0.3 mg/100 g and 1.0 mg/100 g, respectively. Bovine lactoferrin within the concentration range of 10–1000 nmol L⁻¹ showed a strong linear relationship with a linear correlation coefficient (r) of >0.998. The intra- and inter-day precision of the method were RSD < 6.5% and RSD < 7.1%, respectively. Excellent repeatability (RSD < 6.4%) substantially supported the application of this method for the determination of bovine lactoferrin in dairy samples. The present method

Determination of bovine lactoferrin in dairy products by ultra-high performance liquid chromatography–tandem mass spectrometry based on tryptic signature peptides employing an isotope-labeled winged peptide as internal standard

International Nuclear Information System (INIS)

Zhang, Jingshun; Lai, Shiyun; Cai, Zengxuan; Chen, Qi; Huang, Baifen; Ren, Yiping

2014-01-01

Highlights: • A UHPLC–MS/MS method for quantification of bovine lactoferrin was developed. • Tryptic fragment LRPVAAEIYGTK was chosen as signature peptide of bovine lactoferrin. • A winged peptide containing isotopically-labeled signature peptide was designed as internal standard. • The method for determining lactoferrin does not discriminate between the different forms of lactoferrin. • Meet the growing demand to quantify bovine lactoferrin in different dairy products. - Abstract: A new and sensitive determination method was developed for bovine lactoferrin in dairy products including infant formulas based on the signature peptide by ultra high-performance liquid chromatography and triple-quadrupole tandem mass spectrometry under the multiple reaction monitoring mode. The simple pretreatment procedures included the addition of a winged peptide containing the isotope-labeled signature peptide as internal standard, followed by an enzymatic digestion with trypsin. The signature peptide was chosen and identified from the tryptic hydrolyzates of bovine lactoferrin by ultra high-performance liquid chromatography and quadrupole-time-of-flight tandem mass spectrometry based on sequence database search. Analytes were separated on an ACQUITY UPLC BEH 300 C18 column and monitored by MS/MS in seven minutes. Quantitative result bias due to matrix effect and tryptic efficiency was corrected through the use of synthetic isotope-labeled standards. The limit of detection and limit of quantification were 0.3 mg/100 g and 1.0 mg/100 g, respectively. Bovine lactoferrin within the concentration range of 10–1000 nmol L −1 showed a strong linear relationship with a linear correlation coefficient (r) of >0.998. The intra- and inter-day precision of the method were RSD < 6.5% and RSD < 7.1%, respectively. Excellent repeatability (RSD < 6.4%) substantially supported the application of this method for the determination of bovine lactoferrin in dairy samples. The present

Metabolic effects of beta2-agonists in relation to exercise performance

DEFF Research Database (Denmark)

Kalsen, Anders

2015-01-01

athletes. The present PhD thesis is based on four manuscripts in which the acute effects of beta2-agonists on exercise performance were investigated. The aims were 1) to investigate whether supratherapeutic inhalation of beta2-agonists enhances muscle strength, anaerobic performance and aerobic performance......, 2) to uncover the mechanisms behind potential beta2-adrenergic improvements in anaerobic performance, 3) to investigate whether inhalation of beta2-agonists is ergogenic in elite athletes with or without airway hyperresponsiveness (AHR). Results from the studies of the thesis show...... administration of a certain dose, but a further increase in dose does not seem to elicit a greater performance-enhancing effect. Moreover, the effects of beta2-agonists on performance are unaffected by training status and AHR, but athletes with AHR who regularly use beta2-agonists get a reduced ergogenic...

Mapping the antigenic structure of porcine parvovirus at the level of peptides

DEFF Research Database (Denmark)

Kamstrup, Søren; Langeveld, Jan; Bøtner, Anette

1998-01-01

The antigenic structure of the capsid proteins of porcine parvovirus (PPV) was investigated. A total of nine linear epitopes were identified by Pepscan using porcine or rabbit anti-PPV antisera. No sites were identified with a panel of neutralising monoclonal antibodies (MAbs). All epitopes were...... located in the region corresponding to the major capsid protein VP2. Based on this information, and on analogy to other autonomous parvoviruses, 24 different peptides were synthesised, coupled to keyhole limpet haemocyanin (KLH) and used to immunise rabbits. Most antisera were able to bind viral protein....... It is concluded that in PPV, the VP2 N-terminus is involved in virus neutralisation (VN) and peptides from this region are therefore primary targets for developing peptide-based vaccines against this virus....

FMRFamide-gated sodium channel and ASIC channels: a new class of ionotropic receptors for FMRFamide and related peptides.

Science.gov (United States)

Lingueglia, Eric; Deval, Emmanuel; Lazdunski, Michel

2006-05-01

FMRFamide and related peptides typically exert their action through G-protein coupled receptors. However, two ionotropic receptors for these peptides have recently been identified. They are both members of the epithelial amiloride-sensitive Na+ channel and degenerin (ENaC/DEG) family of ion channels. The invertebrate FMRFamide-gated Na+ channel (FaNaC) is a neuronal Na+-selective channel which is directly gated by micromolar concentrations of FMRFamide and related tetrapeptides. Its response is fast and partially desensitizing, and FaNaC has been proposed to participate in peptidergic neurotransmission. On the other hand, mammalian acid-sensing ion channels (ASICs) are not gated but are directly modulated by FMRFamide and related mammalian peptides like NPFF and NPSF. ASICs are activated by external protons and are therefore extracellular pH sensors. They are expressed both in the central and peripheral nervous system and appear to be involved in many physiological and pathophysiological processes such as hippocampal long-term potentiation and defects in learning and memory, acquired fear-related behavior, retinal function, brain ischemia, pain sensation in ischemia and inflammation, taste perception, hearing functions, and mechanoperception. The potentiation of ASIC activity by endogenous RFamide neuropeptides probably participates in the response to noxious acidosis in sensory and central neurons. Available data also raises the possibility of the existence of still unknown FMRFamide related endogenous peptides acting as direct agonists for ASICs.

Sensing lymphoma cells based on a cell-penetrating/apoptosis-inducing/electron-transfer peptide probe

International Nuclear Information System (INIS)

Sugawara, Kazuharu; Shinohara, Hiroki; Kadoya, Toshihiko; Kuramitz, Hideki

2016-01-01

To electrochemically sense lymphoma cells (U937), we fabricated a multifunctional peptide probe that consists of cell-penetrating/apoptosis-inducing/electron-transfer peptides. Electron-transfer peptides derive from cysteine residue combined with the C-terminals of four tyrosine residues (Y_4). A peptide whereby Y_4C is bound to the C-terminals of protegrin 1 (RGGRLCYCRRRFCVCVGR-NH_2) is known to be an apoptosis-inducing agent against U937 cells, and is referred to as a peptide-1 probe. An oxidation response of the peptide-1 probe has been observed due to a phenolic hydroxyl group, and this response is decreased by the uptake of the peptide probe into the cells. To improve the cell membrane permeability against U937 cells, the RGGR at the N-terminals of the peptide-1 probe was replaced by RRRR (peptide-2 probe). In contrast, RNRCKGTDVQAWY_4C (peptide-3 probe), which recognizes ovalbumin, was constructed as a control. Compared with the other probes, the change in the peak current of the peptide-2 probe was the greatest at low concentrations and occurred in a short amount of time. Therefore, the cell membrane permeability of the peptide-2 probe was increased based on the arginine residues and the apoptosis-inducing peptides. The peak current was linear and ranged from 100 to 1000 cells/ml. The relative standard deviation of 600 cells/ml was 5.0% (n = 5). Furthermore, the membrane permeability of the peptide probes was confirmed using fluorescent dye. - Highlights: • We constructed a multifunctional peptide probe for the electrochemical sensing of lymphoma cells. • The peptide probe consists of cell-penetrating/apoptosis-inducing/electron-transfer peptides. • The electrode response of the peptide probe changes due to selective uptake into the cells.

Sensing lymphoma cells based on a cell-penetrating/apoptosis-inducing/electron-transfer peptide probe

Energy Technology Data Exchange (ETDEWEB)

Sugawara, Kazuharu, E-mail: kzsuga@maebashi-it.ac.jp [Maebashi Institute of Technology, Gunma 371-0816 (Japan); Shinohara, Hiroki; Kadoya, Toshihiko [Maebashi Institute of Technology, Gunma 371-0816 (Japan); Kuramitz, Hideki [Department of Environmental Biology and Chemistry, Graduate School of Science and Engineering for Research, University of Toyama, Toyama 930-8555 (Japan)

2016-06-14

To electrochemically sense lymphoma cells (U937), we fabricated a multifunctional peptide probe that consists of cell-penetrating/apoptosis-inducing/electron-transfer peptides. Electron-transfer peptides derive from cysteine residue combined with the C-terminals of four tyrosine residues (Y{sub 4}). A peptide whereby Y{sub 4}C is bound to the C-terminals of protegrin 1 (RGGRLCYCRRRFCVCVGR-NH{sub 2}) is known to be an apoptosis-inducing agent against U937 cells, and is referred to as a peptide-1 probe. An oxidation response of the peptide-1 probe has been observed due to a phenolic hydroxyl group, and this response is decreased by the uptake of the peptide probe into the cells. To improve the cell membrane permeability against U937 cells, the RGGR at the N-terminals of the peptide-1 probe was replaced by RRRR (peptide-2 probe). In contrast, RNRCKGTDVQAWY{sub 4}C (peptide-3 probe), which recognizes ovalbumin, was constructed as a control. Compared with the other probes, the change in the peak current of the peptide-2 probe was the greatest at low concentrations and occurred in a short amount of time. Therefore, the cell membrane permeability of the peptide-2 probe was increased based on the arginine residues and the apoptosis-inducing peptides. The peak current was linear and ranged from 100 to 1000 cells/ml. The relative standard deviation of 600 cells/ml was 5.0% (n = 5). Furthermore, the membrane permeability of the peptide probes was confirmed using fluorescent dye. - Highlights: • We constructed a multifunctional peptide probe for the electrochemical sensing of lymphoma cells. • The peptide probe consists of cell-penetrating/apoptosis-inducing/electron-transfer peptides. • The electrode response of the peptide probe changes due to selective uptake into the cells.

PPARα-Independent Arterial Smooth Muscle Relaxant Effects of PPARα Agonists

Directory of Open Access Journals (Sweden)

Neerupma Silswal

2012-01-01

Full Text Available We sought to determine direct vascular effects of peroxisome proliferator-activated receptor alpha (PPARα agonists using isolated mouse aortas and middle cerebral arteries (MCAs. The PPARα agonists GW7647, WY14643, and gemfibrozil acutely relaxed aortas held under isometric tension and dilated pressurized MCAs with the following order of potency: GW7647≫WY14643>gemfibrozil. Responses were endothelium-independent, and the use of PPARα deficient mice demonstrated that responses were also PPARα-independent. Pretreating arteries with high extracellular K+ attenuated PPARα agonist-mediated relaxations in the aorta, but not in the MCA. In the aorta, the ATP sensitive potassium (KATP channel blocker glibenclamide also impaired relaxations whereas the other K+ channel inhibitors, 4-aminopyridine and Iberiotoxin, had no effect. In aortas, GW7647 and WY14643 elevated cGMP levels by stimulating soluble guanylyl cyclase (sGC, and inhibition of sGC with ODQ blunted relaxations to PPARα agonists. In the MCA, dilations were inhibited by the protein kinase C (PKC activator, phorbol 12,13-dibutyrate, and also by ODQ. Our results demonstrated acute, nonreceptor-mediated relaxant effects of PPARα agonists on smooth muscle of mouse arteries. Responses to PPARα agonists in the aorta involved KATP channels and sGC, whereas in the MCA the PKC and sGC pathways also appeared to contribute to the response.

Long-Term Treatment with Liraglutide, a Glucagon-Like Peptide-1 (GLP-1 Receptor Agonist, Has No Effect on β-Amyloid Plaque Load in Two Transgenic APP/PS1 Mouse Models of Alzheimer's Disease.

Directory of Open Access Journals (Sweden)

Henrik H Hansen

Full Text Available One of the major histopathological hallmarks of Alzheimer's disease (AD is cerebral deposits of extracellular β-amyloid peptides. Preclinical studies have pointed to glucagon-like peptide 1 (GLP-1 receptors as a potential novel target in the treatment of AD. GLP-1 receptor agonists, including exendin-4 and liraglutide, have been shown to promote plaque-lowering and mnemonic effects of in a number of experimental models of AD. Transgenic mouse models carrying genetic mutations of amyloid protein precursor (APP and presenilin-1 (PS1 are commonly used to assess the pharmacodynamics of potential amyloidosis-lowering and pro-cognitive compounds. In this study, effects of long-term liraglutide treatment were therefore determined in two double APP/PS1 transgenic mouse models of Alzheimer's disease carrying different clinical APP/PS1 mutations, i.e. the 'London' (hAPPLon/PS1A246E and 'Swedish' mutation variant (hAPPSwe/PS1ΔE9 of APP, with co-expression of distinct PS1 variants. Liraglutide was administered in 5 month-old hAPPLon/PS1A246E mice for 3 months (100 or 500 ng/kg/day, s.c., or 7 month-old hAPPSwe/PS1ΔE9 mice for 5 months (500 ng/kg/day, s.c.. In both models, regional plaque load was quantified throughout the brain using stereological methods. Vehicle-dosed hAPPSwe/PS1ΔE9 mice exhibited considerably higher cerebral plaque load than hAPPLon/PS1A246E control mice. Compared to vehicle-dosed transgenic controls, liraglutide treatment had no effect on the plaque levels in hAPPLon/PS1A246E and hAPPSwe/PS1ΔE9 mice. In conclusion, long-term liraglutide treatment exhibited no effect on cerebral plaque load in two transgenic mouse models of low- and high-grade amyloidosis, which suggests differential sensitivity to long-term liraglutide treatment in various transgenic mouse models mimicking distinct pathological hallmarks of AD.

Subtype selective kainic acid receptor agonists

DEFF Research Database (Denmark)

Bunch, Lennart; Krogsgaard-Larsen, Povl

2009-01-01

(S)-Glutamic acid (Glu) is the major excitatory neurotransmitter in the mammalian central nervous system, activating the plethora of glutamate receptors (GluRs). In broad lines, the GluRs are divided into two major classes: the ionotropic Glu receptors (iGluRs) and the metabotropic Glu receptors (m......GluRs). Within the iGluRs, five subtypes (KA1, KA2, iGluR5-7) show high affinity and express full agonist activity upon binding of the naturally occurring amino acid kainic acid (KA). Thus these receptors have been named the KA receptors. This review describes all-to our knowledge-published KA receptor agonists...

A novel monoclonal antibody to a defined peptide epitope in MUC16

DEFF Research Database (Denmark)

Marcos-Silva, Lara; Ricardo, Sara; Chen, Kowa

2015-01-01

with the tandem-repeat region, their epitopes appear to be conformational dependent and not definable by a short peptide. Aberrant glycoforms of MUC16 may constitute promising targets for diagnostic and immunotherapeutic intervention, and it is important to develop well-defined immunogens for induction of potent...... immunodominant linear peptide epitopes within the tandem repeat. We developed one monoclonal antibody, 5E11, reactive with a minimum epitope with the sequence FNTTER. This sequence contains potential N- and O-glycosylation sites and, interestingly, glycosylation blocked binding of 5E11. In immunochemistry...

Effects of Glucagon-Like Peptide-1 Receptor Agonists on Weight Loss in Patients with Type 2 Diabetes: A Systematic Review and Network Meta-Analysis

Directory of Open Access Journals (Sweden)

Feng Sun

2015-01-01

Full Text Available To evaluate the effectiveness of glucagon-like peptide-1 receptor agonists (GLP-1 RAs on weight reduction in patients with Type 2 diabetes mellitus (Type 2 DM, a network meta-analysis was conducted. MEDLINE, EMBASE, Cochrane Library, and ClinicalTrials.gov were searched from 1950 to October 2013. Randomized controlled trials (RCTs involving GLP-1 RAs were included if they provided information on body weight. A total of 51 RCTs were included and 17521 participants were enrolled. The mean duration of 51 RCTs was 31 weeks. Exenatide 10 μg twice daily (EX10BID reduced weight compared with exenatide 5 μg twice daily (EX5BID, liraglutide 0.6 mg once daily (LIR0.6QD, liraglutide—1.2 mg once daily (LIR1.2QD, and placebo treatment, with mean differences of −1.07 kg (95% CI: −2.41, −0.02, −2.38 kg (95% CI: −3.71, −1.06, −1.62 kg (95% CI: −2.79, −0.43, and −1.92 kg (95% CI: −2.61, −1.24, respectively. Reductions of weight treated with liraglutide—1.8 mg once daily (LIR1.8QD reach statistical significance (−1.43 kg (95% CI: −2.73, −0.15 versus LIR1.2QD and (−0.98 kg (95% CI: −1.94, −0.02 versus placebo. Network meta-analysis found that EX10BID, LIR1.8QD, and EX2QW obtained a higher proportion of patients with weight loss than other traditional hypoglycemic agents. Our results suggest GLP-1 RAs are promising candidates for weight control in comparison with traditional hypoglycemic drugs, and EX10BID, LIR1.8QD, and EX2QW rank the top three drugs.

Glucagon-like peptide-1 receptor agonists compared with basal insulins for the treatment of type 2 diabetes mellitus: a systematic review and meta-analysis.

Science.gov (United States)

Singh, Sonal; Wright, Eugene E; Kwan, Anita Y M; Thompson, Juliette C; Syed, Iqra A; Korol, Ellen E; Waser, Nathalie A; Yu, Maria B; Juneja, Rattan

2017-02-01

Since 2005, several glucagon-like peptide-1 receptor agonists (GLP-1 RAs) have been approved to treat people with type 2 diabetes. These agents are considered for use at the same point in the treatment paradigm as basal insulins. A comprehensive comparison of these drug classes, therefore, can help inform treatment decisions. This systematic review and meta-analysis assessed the clinical efficacy and safety of GLP-1 RAs compared with basal insulins. MEDLINE, EMBASE, CENTRAL and PubMed databases were searched. Randomized clinical trials (RCTs) of ≥16 weeks' duration comparing GLP-1 RAs vs basal insulins in adults with type 2 diabetes inadequately controlled with oral antihyperglycemic drugs were included. Data on the change from baseline to 26 weeks (±10 weeks) of treatment in hemoglobin A1c (HbA1c) and weight, as well as the proportion of patients experiencing hypoglycaemia, were extracted. Fixed-effect pairwise meta-analyses were conducted where data were available from ≥2 studies. Fifteen RCTs were identified and 11 were meta-analysed. The once-weekly GLP-1 RAs, exenatide long acting release (LAR) and dulaglutide, led to greater, statistically significant mean HbA1c reductions vs basal insulins (exenatide: -0.31% [95% confidence interval -0.42, -0.19], dulaglutide: -0.39% [-0.49, -0.29]) whilst once-daily liraglutide and twice-daily exenatide did not (liraglutide: 0.06% [-0.06, 0.18], exenatide: 0.01% [-0.11, 0.13]). Mean weight reduction was seen with all GLP-1 RAs while mean weight gain was seen with basal insulins. Interpretation of the analysis of hypoglycaemia was limited by inconsistent definitions and reporting. Because of the limited number of available studies sensitivity analyses to explore heterogeneity could not be conducted. Although weight reduction is seen with all GLP-1 RA's, only the once-weekly agents, exenatide LAR and dulaglutide, demonstrate significant HbA1c reductions when compared to basal insulins. © 2016 The Authors. Diabetes

Studies of linear Gramicidin synthesis in Bacillus brevis ATCC 8185

International Nuclear Information System (INIS)

Kubota, Kou; Kagawa, Kenichi

1976-01-01

Bacillus brevis ATCC 8185 was grown in polypepton and Ehrlich's meat extract medium, and this strain produced two kinds of peptide antibiotics, Tyrocidine and linear Gramicidin. A simple chromatographic method was developed for the isolation of linear Gramicidin from mixture Tyrothricin, applied on the column. Trimethoprim, an inhibitor of dihydrofolate reductase, inhibits the synthesis of both peptides in the growing culture with slight inhibition to cell growth. Serine- 14 C is incorporated in the Gramicidin, and recovered as ethanol amine and glycine by the hydrolysis of 14 C-labeled Gramicidin, but deoxypyridoxine-HCl, B 6 antagonist, has no effect on the production of antibiotics in the culture. Linear Gramicidin gives two spots on the thin layer chromatogram (TLC) developed by ethyl acetate-pyridine-water system of 16:4:2, and by chloroform-methanol-water system of 17:3:0.3. The incorporations of constitutive 14 C-labeled amino acids, ethanol amine, and sodium formate into linear Gramicidin were studied by growing cells. These labeled specimens were identified to correspond to authentic specimens which migrated on TLC. Cells were hydrolysed with Lysozyme, and the crude extract was prepared between 0.33 and 0.45 saturation of ammonium sulfate. It activated constituent amino acids including D-leucine by ATP- 32 PPi exchange reaction, but hardly activated L-serine, D-valine, and formyl L-valine. (Kobatake, H.)

Ecdysone Agonist: New Insecticides with Novel Mode of Action

Directory of Open Access Journals (Sweden)

Y. Andi Trisyono

2002-12-01

Full Text Available Development of insect resistance to insecticide has been the major driving force for the development of new insecticides. Awareness and demand from public for more environmentally friendly insecticides have contributed in shifting the trend from using broad spectrum to selective insecticides. As a result, scientists have looked for new target sites beyond the nervous system. Insect growth regulators (IGRs are more selective insecticides than conventional insecticides, and ecdysone agonists are the newest IGRs being commercialized, e.g. tebufenozide, methoxyfenozide, and halofenozide. Ecdysone agonists bind to the ecdysteroid receptors, and they act similarly to the molting hormone 20-hydroxyecdysone. The binding provides larvae or nymphs with a signal to enter a premature and lethal molting cycle. In addition, the ecdysone agonists cause a reduction in the number of eggs laid by female insects. The ecdysone agonists are being developed as selective biorational insecticides. Tebufenozide and methoxyfenozide are used to control lepidopteran insect pests, whereas halofenozide is being used to control coleopteran insect pests. Their selectivity is due to differences in the binding affinity between these compounds to the receptors in insects from different orders. The selectivity of these compounds makes them candidates to be used in combinations with other control strategies to develop integrated pest management programs in agricultural ecosystems. Key words: new insecticides, selectivity, ecdysone agonists

N-terminal pro brain natriuretic peptide as a cardiac biomarker in Japanese hemodialysis patients.

Science.gov (United States)

Shimizu, Minako; Doi, Shigehiro; Nakashima, Ayumu; Naito, Takayuki; Masaki, Takao

2018-03-01

This study examined the clinical significance of N-terminal pro brain natriuretic peptide level as a cardiac marker in Japanese hemodialysis patients. This was a multicenter cross-sectional study involving 1428 Japanese hemodialysis patients. Ultrasonic cardiography data at post-hemodialysis were obtained from 395 patients. We examined whether serum N-terminal pro brain natriuretic peptide levels were associated with cardiac parameters and assessed cut-off values and investigated factors associated with a reduced ratio of N-terminal pro brain natriuretic peptide levels pre- and post-hemodialysis. Multivariate logistic regression analysis showed that pre- and post-hemodialysis N-terminal pro brain natriuretic peptide levels were associated with left ventricular hypertrophy on electrocardiogram (odds ratio: 3.10; p N-terminal pro brain natriuretic peptide levels were also significantly associated with ejection fraction on urine chorionic gonadotrophin (ultrasonic cardiography; odds ratio: 35.83; p N-terminal pro brain natriuretic peptide reduction ratio during a hemodialysis session correlated with Kt/V, membrane area, membrane type, modality, body weight gain ratio, treatment time, and ultrafiltration rate with multiple linear regression ( R: 0.53; p N-terminal pro brain natriuretic peptide are associated with the presence of left ventricular hypertrophy in this population. The post-hemodialysis N-terminal pro brain natriuretic peptide level is a useful marker for systolic dysfunction.

Peptide array-based interaction assay of solid-bound peptides and anchorage-dependant cells and its effectiveness in cell-adhesive peptide design.

Science.gov (United States)

Kato, Ryuji; Kaga, Chiaki; Kunimatsu, Mitoshi; Kobayashi, Takeshi; Honda, Hiroyuki

2006-06-01

Peptide array, the designable peptide library covalently synthesized on cellulose support, was applied to assay peptide-cell interaction, between solid-bound peptides and anchorage-dependant cells, to study objective peptide design. As a model case, cell-adhesive peptides that could enhance cell growth as tissue engineering scaffold material, was studied. On the peptide array, the relative cell-adhesion ratio of NIH/3T3 cells was 2.5-fold higher on the RGDS (Arg-Gly-Asp-Ser) peptide spot as compared to the spot with no peptide, thus indicating integrin-mediated peptide-cell interaction. Such strong cell adhesion mediated by the RGDS peptide was easily disrupted by single residue substitution on the peptide array, thus indicating that the sequence recognition accuracy of cells was strictly conserved in our optimized scheme. The observed cellular morphological extension with active actin stress-fiber on the RGD motif-containing peptide supported our strategy that peptide array-based interaction assay of solid-bound peptide and anchorage-dependant cells (PIASPAC) could provide quantitative data on biological peptide-cell interaction. The analysis of 180 peptides obtained from fibronectin type III domain (no. 1447-1629) yielded 18 novel cell-adhesive peptides without the RGD motif. Taken together with the novel candidates, representative rules of ineffective amino acid usage were obtained from non-effective candidate sequences for the effective designing of cell-adhesive peptides. On comparing the amino acid usage of the top 20 and last 20 peptides from the 180 peptides, the following four brief design rules were indicated: (i) Arg or Lys of positively charged amino acids (except His) could enhance cell adhesion, (ii) small hydrophilic amino acids are favored in cell-adhesion peptides, (iii) negatively charged amino acids and small amino acids (except Gly) could reduce cell adhesion, and (iv) Cys and Met could be excluded from the sequence combination since they have

A peptide affinity column for the identification of integrin alpha IIb-binding proteins.

Science.gov (United States)

Daxecker, Heide; Raab, Markus; Bernard, Elise; Devocelle, Marc; Treumann, Achim; Moran, Niamh

2008-03-01

To understand the regulation of integrin alpha(IIb)beta(3), a critical platelet adhesion molecule, we have developed a peptide affinity chromatography method using the known integrin regulatory motif, LAMWKVGFFKR. Using standard Fmoc chemistry, this peptide was synthesized onto a Toyopearl AF-Amino-650 M resin on a 6-aminohexanoic acid (Ahx) linker. Peptide density was controlled by acetylation of 83% of the Ahx amino groups. Four recombinant human proteins (CIB1, PP1, ICln and RN181), previously identified as binding to this integrin regulatory motif, were specifically retained by the column containing the integrin peptide but not by a column presenting an irrelevant peptide. Hemoglobin, creatine kinase, bovine serum albumin, fibrinogen and alpha-tubulin failed to bind under the chosen conditions. Immunodetection methods confirmed the binding of endogenous platelet proteins, including CIB1, PP1, ICln RN181, AUP-1 and beta3-integrin, from a detergent-free platelet lysate. Thus, we describe a reproducible method that facilitates the reliable extraction of specific integrin-binding proteins from complex biological matrices. This methodology may enable the sensitive and specific identification of proteins that interact with linear, membrane-proximal peptide motifs such as the integrin regulatory motif LAMWKVGFFKR.

Albumin-derived peptides efficiently reduce renal uptake of radiolabelled peptides

International Nuclear Information System (INIS)

Vegt, Erik; Eek, Annemarie; Oyen, Wim J.G.; Gotthardt, Martin; Boerman, Otto C.; Jong, Marion de

2010-01-01

In peptide-receptor radionuclide therapy (PRRT), the maximum activity dose that can safely be administered is limited by high renal uptake and retention of radiolabelled peptides. The kidney radiation dose can be reduced by coinfusion of agents that competitively inhibit the reabsorption of radiolabelled peptides, such as positively charged amino acids, Gelofusine, or trypsinised albumin. The aim of this study was to identify more specific and potent inhibitors of the kidney reabsorption of radiolabelled peptides, based on albumin. Albumin was fragmented using cyanogen bromide and six albumin-derived peptides with different numbers of electric charges were selected and synthesised. The effect of albumin fragments (FRALB-C) and selected albumin-derived peptides on the internalisation of 111 In-albumin, 111 In-minigastrin, 111 In-exendin and 111 In-octreotide by megalin-expressing cells was assessed. In rats, the effect of Gelofusine and albumin-derived peptides on the renal uptake and biodistribution of 111 In-minigastrin, 111 In-exendin and 111 In-octreotide was determined. FRALB-C significantly reduced the uptake of all radiolabelled peptides in vitro. The albumin-derived peptides showed different potencies in reducing the uptake of 111 In-albumin, 111 In-exendin and 111 In-minigastrin in vitro. The most efficient albumin-derived peptide (peptide 6), was selected for in vivo testing. In rats, 5 mg of peptide 6 very efficiently inhibited the renal uptake of 111 In-minigastrin, by 88%. Uptake of 111 In-exendin and 111 In-octreotide was reduced by 26 and 33%, respectively. The albumin-derived peptide 6 efficiently inhibited the renal reabsorption of 111 In-minigastrin, 111 In-exendin and 111 In-octreotide and is a promising candidate for kidney protection in PRRT. (orig.)

Reconstitution of high-affinity opioid agonist binding in brain membranes

Energy Technology Data Exchange (ETDEWEB)

Remmers, A.E.; Medzihradsky, F. (Univ. of Michigan Medical School, Ann Arbor (United States))

1991-03-15

In synaptosomal membranes from rat brain cortex, the {mu} selective agonist ({sup 3}H)dihydromorphine in the absence of sodium, and the nonselective antagonist ({sup 3}H)naltrexone in the presence of sodium, bound to two populations of opioid receptor sites with K{sub d} values of 0.69 and 8.7 nM for dihydromorphine, and 0.34 and 5.5 nM for naltrexone. The addition of 5 {mu}M guanosine 5{prime}-({gamma}-thio)triphosphate (GTP({gamma}S)) strongly reduced high-affinity agonist but not antagonist binding. Exposure of the membranes to high pH reduced the number of GTP({gamma}-{sup 35}S) binding sites by 90% and low K{sub m}, opioid-sensitive GTPase activity by 95%. In these membranes, high-affinity agonist binding was abolished and modulation of residual binding by GTP({gamma}S) was diminished. Alkali treatment of the glioma cell membranes prior to fusion inhibited most of the low K{sub m} GTPase activity and prevented the reconstitution of agonist binding. The results show that high-affinity opioid agonist binding reflects the ligand-occupied receptor - guanine nucleotide binding protein complex.

Hypertrophic effect of inhaled beta -agonist with and without concurrent exercise training

DEFF Research Database (Denmark)

Jessen, Søren; Onslev, Johan; Lemminger, Anders

2018-01-01

INTRODUCTION: Due to a high prevalence of asthma and exercise-induced bronchoconstriction in elite athletes, there is a high use of beta2 -adrenoceptor agonists (beta2 -agonists) in the athletic population. While anabolic in rodents, no study has been able to detect hypertrophy in humans after...... chronic beta2 -agonist inhalation. METHODS: We investigated if inhaled beta2 -agonist, terbutaline, alters body composition and metabolic rate with and without concurrent exercise training in healthy young men. Sixty-seven participants completed a four-week intervention of daily terbutaline (8×0.5 mg...

[Rapid determination of illicit beta2-agonist additives in health foods and traditional Chinese patent medicines with DCBI-MS/MS method].

Science.gov (United States)

Hou, Yu-Lan; Wu, Shuang; Wang, Hua; Zhao, Yong; Liao, Peng; Tian, Qing-Qing; Sun, Wen-Jian; Chen, Bo

2013-01-01

A novel rapid method for detection of the illicit beta2-agonist additives in health foods and traditional Chinese patent medicines was developed with the desorption corona beam ionization mass spectrometry (DCBI-MS) technique. The DCBI conditions including temperature and sample volume were optimized according to the resulting mass spectra intensity. Matrix effect on 9 beta2-agonists additives was not significant in the proposed rapid determination procedure. All of the 9 target molecules were detected within 1 min. Quantification was achieved based on the typical fragment ion in MS2 spectra of each analyte. The method showed good linear coefficients in the range of 1-100 mg x L(-1) for all analytes. The relative deviation values were between 14.29% and 25.13%. Ten claimed antitussive and antiasthmatic health foods and traditional Chinese patent medicines from local pharmacies were analyzed. All of them were negative with the proposed DCBI-MS method. Without tedious sample pretreatments, the developed DCBI-MS is simple, rapid and sensitive for rapid qualification and semi-quantification of the illicit beta2-agonist additives in health foods and traditional Chinese patent medicines.

Regulation of ventilation and oxygen consumption by delta- and mu-opioid receptor agonists.

Science.gov (United States)

Schaeffer, J I; Haddad, G G

1985-09-01

To study the effect of endorphins on metabolic rate and on the relationship between O2 consumption (VO2) and ventilation, we administered enkephalin analogues (relatively selective delta-receptor agonists) and a morphiceptin analogue (a highly selective mu-receptor agonist) intracisternally in nine unanesthetized chronically instrumented adult dogs. Both delta- and mu-agonists decreased VO2 by 40-60%. delta-Agonists induced a dose-dependent decrease in mean instantaneous minute ventilation (VT/TT) associated with periodic breathing. The decrease in VT/TT started and resolved prior to the decrease and returned to baseline of VO2, respectively. In contrast, the mu-agonists induced an increase in VT/TT associated with rapid shallow breathing. Arterial PCO2 increased and arterial PO2 decreased after both delta- and mu-agonists. Low doses of intracisternal naloxone (0.002-2.0 micrograms/kg) reversed the opioid effect on VT/TT but not on VO2; higher doses of naloxone (5-25 micrograms/kg) reversed both. Naloxone administered alone had no effect on VT/TT or VO2. These data suggest that 1) both delta- and mu-agonists induce alveolar hypoventilation despite a decrease in VO2, 2) this hypoventilation results from a decrease in VT/TT after delta-agonists but an increase in dead space ventilation after mu-agonists, and 3) endorphins do not modulate ventilation and metabolic rate tonically, but we speculate that they may do so in response to stressful stimulation.

The gastrin-releasing peptide analog bombesin preserves exocrine and endocrine pancreas morphology and function during parenteral nutrition

Science.gov (United States)

Pierre, Joseph F.; Neuman, Joshua C.; Brill, Allison L.; Brar, Harpreet K.; Thompson, Mary F.; Cadena, Mark T.; Connors, Kelsey M.; Busch, Rebecca A.; Heneghan, Aaron F.; Cham, Candace M.; Jones, Elaina K.; Kibbe, Carly R.; Davis, Dawn B.; Groblewski, Guy E.; Kudsk, Kenneth A.

2015-01-01

Stimulation of digestive organs by enteric peptides is lost during total parental nutrition (PN). Here we examine the role of the enteric peptide bombesin (BBS) in stimulation of the exocrine and endocrine pancreas during PN. BBS protects against exocrine pancreas atrophy and dysfunction caused by PN. BBS also augments circulating insulin levels, suggesting an endocrine pancreas phenotype. While no significant changes in gross endocrine pancreas morphology were observed, pancreatic islets isolated from BBS-treated PN mice showed a significantly enhanced insulin secretion response to the glucagon-like peptide-1 (GLP-1) agonist exendin-4, correlating with enhanced GLP-1 receptor expression. BBS itself had no effect on islet function, as reflected in low expression of BBS receptors in islet samples. Intestinal BBS receptor expression was enhanced in PN with BBS, and circulating active GLP-1 levels were significantly enhanced in BBS-treated PN mice. We hypothesized that BBS preserved islet function indirectly, through the enteroendocrine cell-pancreas axis. We confirmed the ability of BBS to directly stimulate intestinal enteroid cells to express the GLP-1 precursor preproglucagon. In conclusion, BBS preserves the exocrine and endocrine pancreas functions during PN; however, the endocrine stimulation is likely indirect, through the enteroendocrine cell-pancreas axis. PMID:26185331

FXR agonist activity of conformationally constrained analogs of GW 4064.

Science.gov (United States)

Akwabi-Ameyaw, Adwoa; Bass, Jonathan Y; Caldwell, Richard D; Caravella, Justin A; Chen, Lihong; Creech, Katrina L; Deaton, David N; Madauss, Kevin P; Marr, Harry B; McFadyen, Robert B; Miller, Aaron B; Navas, Frank; Parks, Derek J; Spearing, Paul K; Todd, Dan; Williams, Shawn P; Bruce Wisely, G

2009-08-15

Two series of conformationally constrained analogs of the FXR agonist GW 4064 1 were prepared. Replacement of the metabolically labile stilbene with either benzothiophene or naphthalene rings led to the identification of potent full agonists 2a and 2g.

Interactions of Bio-Inspired Membranes with Peptides and Peptide-Mimetic Nanoparticles

Directory of Open Access Journals (Sweden)

Michael Sebastiano

2015-08-01

Full Text Available Via Dissipative Particle Dynamics (DPD and implicit solvent coarse-grained (CG Molecular Dynamics (MD we examine the interaction of an amphiphilic cell-penetrating peptide PMLKE and its synthetic counterpart with a bio-inspired membrane. We use the DPD technique to investigate the interaction of peptide-mimetic nanoparticles, or nanopins, with a three-component membrane. The CG MD approach is used to investigate the interaction of a cell-penetrating peptide PMLKE with single-component membrane. We observe the spontaneous binding and subsequent insertion of peptide and nanopin in the membrane by using CG MD and DPD approaches, respectively. In addition, we find that the insertion of peptide and nanopins is mainly driven by the favorable enthalpic interactions between the hydrophobic components of the peptide, or nanopin, and the membrane. Our study provides insights into the mechanism underlying the interactions of amphiphilic peptide and peptide-mimetic nanoparticles with a membrane. The result of this study can be used to guide the functional integration of peptide and peptide-mimetic nanoparticles with a cell membrane.

Metal ion-mediated agonism and agonist enhancement in melanocortin MC1 and MC4 receptors

DEFF Research Database (Denmark)

Holst, Birgitte; Elling, Christian E; Schwartz, Thue W

2002-01-01

-melanocortin stimulating hormone (alpha-MSH) in the MC1 and MC4 receptors, respectively. In the presence of peptide agonist, Zn(II) acted as an enhancer on both receptors, because it shifted the dose-response curves to the left: most pronounced was a 6-fold increase in alpha-MSH potency on the MC1 receptor. The effect......An endogenous metal-ion site in the melanocortin MC1 and MC4 receptors was characterized mainly in transiently transfected COS-7 cells. ZnCl(2) alone stimulated signaling through the Gs pathway with a potency of 11 and 13 microm and an efficacy of 50 and 20% of that of alpha...... affinities and profiles were similar for a number of the 2,2'-bipyridine and 1,10-phenanthroline analogs in complex with Zn(II) in the MC1 and MC4 receptors. However, the potencies and efficacies of the metal-ion complexes were very different in the two receptors, and close to full agonism was obtained...

Fingerprinting Desmosine-Containing Elastin Peptides

Science.gov (United States)

Schräder, Christoph U.; Heinz, Andrea; Majovsky, Petra; Schmelzer, Christian E. H.

2015-05-01

Elastin is a vital protein of the extracellular matrix of jawed vertebrates and provides elasticity to numerous tissues. It is secreted in the form of its soluble precursor tropoelastin, which is subsequently cross-linked in the course of the elastic fiber assembly. The process involves the formation of the two tetrafunctional amino acids desmosine (DES) and isodesmosine (IDES), which are unique to elastin. The resulting high degree of cross-linking confers remarkable properties, including mechanical integrity, insolubility, and long-term stability to the protein. These characteristics hinder the structural elucidation of mature elastin. However, MS2 data of linear and cross-linked peptides released by proteolysis can provide indirect insights into the structure of elastin. In this study, we performed energy-resolved collision-induced dissociation experiments of DES, IDES, their derivatives, and DES-/IDES-containing peptides to determine characteristic product ions. It was found that all investigated compounds yielded the same product ion clusters at elevated collision energies. Elemental composition determination using the exact masses of these ions revealed molecular formulas of the type CxHyN, suggesting that the pyridinium core of DES/IDES remains intact even at relatively high collision energies. The finding of these specific product ions enabled the development of a similarity-based scoring algorithm that was successfully applied on LC-MS/MS data of bovine elastin digests for the identification of DES-/IDES-cross-linked peptides. This approach facilitates the straightforward investigation of native cross-links in elastin.

[Plant signaling peptides. Cysteine-rich peptides].

Science.gov (United States)

Ostrowski, Maciej; Kowalczyk, Stanisław

2015-01-01

Recent bioinformatic and genetic analyses of several model plant genomes have revealed the existence of a highly abundant group of signaling peptides that are defined as cysteine-rich peptides (CRPs). CRPs are usually in size between 50 and 90 amino acid residues, they are positively charged, and they contain 4-16 cysteine residues that are important for the correct conformational folding. Despite the structural differences among CRP classes, members from each class have striking similarities in their molecular properties and function. The present review presents the recent progress in research on signaling peptides from several families including: EPF/EPFL, SP11/SCR, PrsS, RALF, LURE, and some other peptides belonging to CRP group. There is convincing evidence indicating multiple roles for these CRPs as signaling molecules during the plant life cycle, ranging from stomata development and patterning, self-incompatibility, pollen tube growth and guidance, reproductive processes, and nodule formation.

Mapping of linear antibody epitopes of the glycoprotein of VHSV, a salmonid rhabdovirus

DEFF Research Database (Denmark)

Fernandez-Alonso, M.; Lorenzo, G.; Perez, L.

1998-01-01

antibodies (MAbs), only 2 non-neutralizing MAbs, I10 (aa 139-153) and IP1H3 (aa 399-413), could be mapped to specific peptides in the pepscan of the gpG. Mapping of these MAbs was confirmed by immunoblotting with recombinant proteins and/or other synthetic peptides covering those sequences. None......Antibody Linear epitopes of the glycoprotein G (gpG) of the viral haemorrhagic septicaemia virus (VHSV), a rhabdovirus of salmonids, were mapped by pepscan using overlapping 15-mer peptides covering the entire gpG sequence and ELISA with polyclonal and monoclonal murine and polyclonal trout...... antibodies. Among the regions recognized in the pepscan by the polyclonal antibodies (PAbs) were the previously identified phosphatidylserine binding heptad-repeats (Estepa & Coll 1996; Virology 216:60-70) and leucocyte stimulating peptides (Lorenzo et al. 1995; Virology 212:348-355). Among 17 monoclonal...

Enhanced efficacy (intrinsic activity) of cyclic opioid peptide analogs at the μ-receptor

International Nuclear Information System (INIS)

Schiller, P.W.; Lemieux, C.; Nguyen, T.M.D.; Maziak, L.A.

1986-01-01

Side-chain to end group cyclized enkephalin analogs (e.g. H-Tyr-cyclo[-D-Lys-Gly-Phe-Leu-] and cyclic opioid peptide analogs obtained through covalent linkage of two side-chains (e.g. H-Tyr-D-Cys-Gly-Phe-Cys-NH 2 or H-Tyr-D-Lys-Gly-Phe-Glu-NH 3 ) were tested in the μ-receptor-representative guinea pig ileum (GPI) bioassay and in a binding assay based on displacement of the μ-ligand [ 3 H]DAGO from rat brain membranes. The cyclic analogs were 5 to 70 times more potent in the GPI assay than in the binding assay, whereas linear analogs showed equal potency in the two assays. These results suggest that the efficacy (intrinsic activity) of cyclic opioid peptide analogs at the μ-receptor is increased as a consequence of the conformation constraint imposed through ring closure. This effect was most pronounced in analogs containing a long hydrophobic sidechain as part of the ring structure in the 2-position of the peptide sequence. Further experimental evidence ruled out the possibilities that these potency discrepancies may be due to differences in enzymatic degradation, dissimilar exposure of the receptors in their lipid environment or interaction with different receptor types in the two assay systems. It can be hypothesized that the semi-rigid cyclic analogs may induce a more productive conformational change in the receptor protein than the linear peptides

Screening and identification of T helper 1 and linear immunodominant antibody-binding epitopes in the spike 2 domain and the nucleocapsid protein of feline infectious peritonitis virus.

Science.gov (United States)

Satoh, Ryoichi; Furukawa, Tomoko; Kotake, Masako; Takano, Tomomi; Motokawa, Kenji; Gemma, Tsuyoshi; Watanabe, Rie; Arai, Setsuo; Hohdatsu, Tsutomu

2011-02-17

The antibody-dependent enhancement (ADE) of feline infectious peritonitis virus (FIPV) infection has been recognized in experimentally infected cats, and cellular immunity is considered to play an important role in preventing the onset of feline infectious peritonitis (FIP). In the present study, we synthesized eighty-one kinds of peptides derived from the spike (S)2 domain of type I FIPV KU-2 strain, the S2 domain of type II FIPV 79-1146 strain, and the nucleocapcid (N) protein of FIPV KU-2 strain. To detect the T helper (Th)1 epitope, peripheral blood mononuclear cells (PBMCs) obtained from FIPV-infected cats were cultured with each peptide, and Th1-type immune responses were measured using feline interferon (fIFN)-γ production as an index. To detect the linear immunodominant antibody-binding epitope, we investigated the reactivity of plasma collected from FIPV-infected cats against each peptide by ELISA. Four and 2 peptides containing Th1 epitopes were identified in the heptad repeat (HR)1 and inter-helical (IH) regions of the S2 domain of type I FIPV, respectively, and these were located on the N-terminal side of the regions. In the S2 domain of type II FIPV, 2, 3, and 2 peptides containing Th1 epitopes were identified in the HR1, IH, and HR2 regions, respectively, and these were mainly located on the C-terminal side of the regions. In the S2 domain of type I FIPV, 3 and 7 peptides containing linear immunodominant antibody-binding epitopes were identified in the IH and HR2 regions, respectively. In the S2 domain of type II FIPV, 4 peptides containing linear immunodominant antibody-binding epitopes were identified in the HR2 region. The Th1 epitopes in the S2 domain of type I and II FIPV were located in different regions, but the linear immunodominant antibody-binding epitopes were mostly located in the HR2 region. Eight peptides containing Th1 epitopes were identified in N protein, and 3 peptides derived from residues 81 to 100 and 137 to 164 showed strong

MELATONIN DAN MELATONIN RECEPTOR AGONIST SEBAGAI PENANGANAN INSOMNIA PRIMER KRONIS

Directory of Open Access Journals (Sweden)

Ni Luh Putu Ayu Maha Iswari

2013-04-01

Full Text Available Melatonin is a hormone that has an important role in the mechanism of sleep. Hypnotic effects of melatonin and melatonin receptor agonist are mediated via MT1 and MT2 receptors, especially in circadian rhythm pacemaker, suprachiasmatic nucleus, which is worked on the hypothalamic sleep switch. This mechanism is quite different with the GABAergic drugs such as benzodiazepine. Agonist melatonin triggers the initiation of sleep and normalize circadian rhythms so that makes it easier to maintain sleep. The main disadvantage of melatonin in helping sleep maintenance on primary insomnia is that the half life is very short. The solution to this problem is the use of prolonged-release melatonin and melatonin receptor agonist agents such as ramelteon. Melatoninergic agonist does not cause withdrawal effects, dependence, as well as cognitive and psychomotor disorders as often happens on the use of benzodiazepine.  

Pharmacologic properties, metabolism, and disposition of linaclotide, a novel therapeutic peptide approved for the treatment of irritable bowel syndrome with constipation and chronic idiopathic constipation.

Science.gov (United States)

Busby, Robert W; Kessler, Marco M; Bartolini, Wilmin P; Bryant, Alexander P; Hannig, Gerhard; Higgins, Carolyn S; Solinga, Robert M; Tobin, Jenny V; Wakefield, James D; Kurtz, Caroline B; Currie, Mark G

2013-01-01

Linaclotide, a potent guanylate cyclase C agonist, is a therapeutic peptide approved in the United States for the treatment of irritable bowel syndrome with constipation and chronic idiopathic constipation. We present for the first time the metabolism, degradation, and disposition of linaclotide in animals and humans. We examined the metabolic stability of linaclotide in conditions that mimic the gastrointestinal tract and characterized the metabolite MM-419447 (CCEYCCNPACTGC), which contributes to the pharmacologic effects of linaclotide. Systemic exposure to these active peptides is low in rats and humans, and the low systemic and portal vein concentrations of linaclotide and MM-419447 observed in the rat confirmed both peptides are minimally absorbed after oral administration. Linaclotide is stable in the acidic environment of the stomach and is converted to MM-419447 in the small intestine. The disulfide bonds of both peptides are reduced in the small intestine, where they are subsequently proteolyzed and degraded. After oral administration of linaclotide, intestinal loops, increased intraluminal cGMP, and caused a dose-dependent acceleration in gastrointestinal transit. These results demonstrate the importance of the active metabolite in contributing to linaclotide's pharmacology.

Refinement of glucagon-like peptide 1 docking to its intact receptor using mid-region photolabile probes and molecular modeling.

Science.gov (United States)

Miller, Laurence J; Chen, Quan; Lam, Polo C-H; Pinon, Delia I; Sexton, Patrick M; Abagyan, Ruben; Dong, Maoqing

2011-05-06

The glucagon-like peptide 1 (GLP1) receptor is an important drug target within the B family of G protein-coupled receptors. Its natural agonist ligand, GLP1, has incretin-like actions and the receptor is a recognized target for management of type 2 diabetes mellitus. Despite recent solution of the structure of the amino terminus of the GLP1 receptor and several close family members, the molecular basis for GLP1 binding to and activation of the intact receptor remains unclear. We previously demonstrated molecular approximations between amino- and carboxyl-terminal residues of GLP1 and its receptor. In this work, we study spatial approximations with the mid-region of this peptide to gain insights into the orientation of the intact receptor and the ligand-receptor complex. We have prepared two new photolabile probes incorporating a p-benzoyl-l-phenylalanine into positions 16 and 20 of GLP1(7-36). Both probes bound to the GLP1 receptor specifically and with high affinity. These were each fully efficacious agonists, stimulating cAMP accumulation in receptor-bearing CHO cells in a concentration-dependent manner. Each probe specifically labeled a single receptor site. Protease cleavage and radiochemical sequencing identified receptor residue Leu(141) above transmembrane segment one as its site of labeling for the position 16 probe, whereas the position 20 probe labeled receptor residue Trp(297) within the second extracellular loop. Establishing ligand residue approximation with this loop region is unique among family members and may help to orient the receptor amino-terminal domain relative to its helical bundle region.

Turn stability in beta-hairpin peptides: Investigation of peptides containing 3:5 type I G1 bulge turns.

Science.gov (United States)

Blandl, Tamas; Cochran, Andrea G; Skelton, Nicholas J

2003-02-01

The turn-forming ability of a series of three-residue sequences was investigated by substituting them into a well-characterized beta-hairpin peptide. The starting scaffold, bhpW, is a disulfide-cyclized 10-residue peptide that folds into a stable beta-hairpin with two antiparallel strands connected by a two-residue reverse turn. Substitution of the central two residues with the three-residue test sequences leads to less stable hairpins, as judged by thiol-disulfide equilibrium measurements. However, analysis of NMR parameters indicated that each molecule retains a significant folded population, and that the type of turn adopted by the three-residue sequence is the same in all cases. The solution structure of a selected peptide with a PDG turn contained an antiparallel beta-hairpin with a 3:5 type I + G1 bulge turn. Analysis of the energetic contributions of individual turn residues in the series of peptides indicates that substitution effects have significant context dependence, limiting the predictive power of individual amino acid propensities for turn formation. The most stable and least stable sequences were also substituted into a more stable disulfide-cyclized scaffold and a linear beta-hairpin scaffold. The relative stabilities remained the same, suggesting that experimental measurements in the bhpW context are a useful way to evaluate turn stability for use in protein design projects. Moreover, these scaffolds are capable of displaying a diverse set of turns, which can be exploited for the mimicry of protein loops or for generating libraries of reverse turns.

[Determination of 23 antibiotics and 3 β-agonists in livestock drinking water by ultra performance liquid chromatography-tandem mass spectrometry coupled with solid-phase extraction].

Science.gov (United States)

Shi, Ao

2016-02-01

A method has been developed for the simultaneous determination of 23 antibiotics (four categories) and 3 β-agonists in livestock drinking water using solid-phase extraction and ultra performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI MS/MS). The samples were adjusted pH to 5. 0, added Na2EDTA, enriched and cleaned-up by an HLB solid-phase extraction cartridge. The target compounds were confirmed and quantified by UPLC-ESI MS/MS with external standard method for the anti- biotics and internal standard method for the β-agonists. The recoveries were assessed by using lab tap water as matrix. The average recoveries of the 23 antibiotics and the 3 β-agonists were in the range of 50. 7%-104. 6% and the relative standard deviations (RSDs) were 2. 6%-8. 8% (n= 3). Under the optimal conditions, the calibration curves of the 23 antibiotics and the 3 β-agonists showed good linearity with the correlation coefficients better than 0. 994. The limits of detection (LODs, S/N≥3) ranged from 0. 01-0. 20 ng/L. The developed method was applied to analyze the livestock drinking waters in 36 Beijing intensive livestock farms. The results showed that some antibiotics were detected.

Human peptide transporters

DEFF Research Database (Denmark)

Nielsen, Carsten Uhd; Brodin, Birger; Jørgensen, Flemming Steen

2002-01-01

Peptide transporters are epithelial solute carriers. Their functional role has been characterised in the small intestine and proximal tubules, where they are involved in absorption of dietary peptides and peptide reabsorption, respectively. Currently, two peptide transporters, PepT1 and PepT2, wh...

Peptide dendrimers

Czech Academy of Sciences Publication Activity Database

Niederhafner, Petr; Šebestík, Jaroslav; Ježek, Jan

2005-01-01

Roč. 11, - (2005), 757-788 ISSN 1075-2617 R&D Projects: GA ČR(CZ) GA203/03/1362 Institutional research plan: CEZ:AV0Z40550506 Keywords : multiple antigen peptides * peptide dendrimers * synthetic vaccine * multipleantigenic peptides Subject RIV: CC - Organic Chemistry Impact factor: 1.803, year: 2005

Rat Urinary Bladder Carcinogenesis by Dual-Acting PPARα+γ Agonists

Directory of Open Access Journals (Sweden)

Martin B. Oleksiewicz

2008-01-01

Full Text Available Despite clinical promise, dual-acting activators of PPARα and γ (here termed PPARα+γ agonists have experienced high attrition rates in preclinical and early clinical development, due to toxicity. In some cases, discontinuation was due to carcinogenic effect in the rat urothelium, the epithelial layer lining the urinary bladder, ureters, and kidney pelvis. Chronic pharmacological activation of PPARα is invariably associated with cancer in rats and mice. Chronic pharmacological activation of PPARγ can in some cases also cause cancer in rats and mice. Urothelial cells coexpress PPARα as well as PPARγ, making it plausible that the urothelial carcinogenicity of PPARα+γ agonists may be caused by receptor-mediated effects (exaggerated pharmacology. Based on previously published mode of action data for the PPARα+γ agonist ragaglitazar, and the available literature about the role of PPARα and γ in rodent carcinogenesis, we propose a mode of action hypothesis for the carcinogenic effect of PPARα+γ agonists in the rat urothelium, which combines receptor-mediated and off-target cytotoxic effects. The proposed mode of action hypothesis is being explored in our laboratories, towards understanding the human relevance of the rat cancer findings, and developing rapid in vitro or short-term in vivo screening approaches to faciliate development of new dual-acting PPAR agonist compounds.

Practical multipeptide synthesis: dedicated software for the definition of multiple, overlapping peptides covering polypeptide sequences.

Science.gov (United States)

Heegaard, P M; Holm, A; Hagerup, M

1993-01-01

A personal computer program for the conversion of linear amino acid sequences to multiple, small, overlapping peptide sequences has been developed. Peptide lengths and "jumps" (the distance between two consecutive overlapping peptides) are defined by the user. To facilitate the use of the program for parallel solid-phase chemical peptide syntheses for the synchronous production of multiple peptides, amino acids at each acylation step are laid out by the program in a convenient standard multi-well setup. Also, the total number of equivalents, as well as the derived amount in milligrams (depend-ending on user-defined equivalent weights and molar surplus), of each amino acid are given. The program facilitates the implementation of multipeptide synthesis, e.g., for the elucidation of polypeptide structure-function relationships, and greatly reduces the risk of introducing mistakes at the planning step. It is written in Pascal and runs on any DOS-based personal computer. No special graphic display is needed.

Dermorphin-related peptides from the skin of Phyllomedusa bicolor and their amidated analogs activate two mu opioid receptor subtypes that modulate antinociception and catalepsy in the rat.

Science.gov (United States)

Negri, L; Erspamer, G F; Severini, C; Potenza, R L; Melchiorri, P; Erspamer, V

1992-08-01

Three naturally occurring dermorphin-like peptides from the skin of the frog Phyllomedusa bicolor, the related carboxyl-terminal amides, and some substituted analogs were synthesized, their binding profiles to opioid receptors were determined, and their biological activities were studied in isolated organ preparations and intact animals. The opioid binding profile revealed a very high selectivity of these peptides for mu sites and suggested the existence of two receptor subtypes, of high and low affinity. The peptides tested acted as potent mu opioid agonists on isolated organ preparations. They were several times more active in inhibiting electrically evoked contractions in guinea pig ileum than in mouse vas deferens. When injected into the lateral brain ventricle or peritoneum of rats, the high-affinity-site-preferring ligand, [Lys7-NH2]dermorphin, behaved as a potent analgesic agent. By contrast, the low-affinity-site-preferring ligand, [Trp4,Asn7-NH2]dermorphin, produced a weak antinociception but an intense catalepsy.

Principles of agonist recognition in Cys-loop receptors

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Timothy eLynagh

2014-04-01

Full Text Available Cys-loop receptors are ligand-gated ion channels that are activated by a structurally diverse array of neurotransmitters, including acetylcholine, serotonin, glycine and GABA. After the term chemoreceptor emerged over 100 years ago, there was some wait until affinity labeling, molecular cloning, functional studies and X-ray crystallography experiments identified the extracellular interface of adjacent subunits as the principal site of agonist binding. The question of how subtle differences at and around agonist-binding sites of different Cys-loop receptors can accommodate transmitters as chemically diverse as glycine and serotonin has been subject to intense research over the last three decades. This review outlines the functional diversity and current structural understanding of agonist-binding sites, including those of invertebrate Cys-loop receptors. Together, this provides a framework to understand the atomic determinants involved in how these valuable therapeutic targets recognize and bind their ligands.

Crystal structure of the ligand-bound glucagon-like peptide-1 receptor extracellular domain.

Science.gov (United States)

Runge, Steffen; Thøgersen, Henning; Madsen, Kjeld; Lau, Jesper; Rudolph, Rainer

2008-04-25

The glucagon-like peptide-1 receptor (GLP-1R) belongs to Family B1 of the seven-transmembrane G protein-coupled receptors, and its natural agonist ligand is the peptide hormone glucagon-like peptide-1 (GLP-1). GLP-1 is involved in glucose homeostasis, and activation of GLP-1R in the plasma membrane of pancreatic beta-cells potentiates glucose-dependent insulin secretion. The N-terminal extracellular domain (nGLP-1R) is an important ligand binding domain that binds GLP-1 and the homologous peptide Exendin-4 with differential affinity. Exendin-4 has a C-terminal extension of nine amino acid residues known as the "Trp cage", which is absent in GLP-1. The Trp cage was believed to interact with nGLP-1R and thereby explain the superior affinity of Exendin-4. However, the molecular details that govern ligand binding and specificity of nGLP-1R remain undefined. Here we report the crystal structure of human nGLP-1R in complex with the antagonist Exendin-4(9-39) solved by the multiwavelength anomalous dispersion method to 2.2A resolution. The structure reveals that Exendin-4(9-39) is an amphipathic alpha-helix forming both hydrophobic and hydrophilic interactions with nGLP-1R. The Trp cage of Exendin-4 is not involved in binding to nGLP-1R. The hydrophobic binding site of nGLP-1R is defined by discontinuous segments including primarily a well defined alpha-helix in the N terminus of nGLP-1R and a loop between two antiparallel beta-strands. The structure provides for the first time detailed molecular insight into ligand binding of the human GLP-1 receptor, an established target for treatment of type 2 diabetes.

Immature osteoblastic MG63 cells possess two calcitonin gene-related peptide receptor subtypes that respond differently to [Cys(Acm)(2,7)] calcitonin gene-related peptide and CGRP(8-37).

Science.gov (United States)

Kawase, Tomoyuki; Okuda, Kazuhiro; Burns, Douglas M

2005-10-01

Calcitonin gene-related peptide (CGRP) is clearly an anabolic factor in skeletal tissue, but the distribution of CGRP receptor (CGRPR) subtypes in osteoblastic cells is poorly understood. We previously demonstrated that the CGRPR expressed in osteoblastic MG63 cells does not match exactly the known characteristics of the classic subtype 1 receptor (CGRPR1). The aim of the present study was to further characterize the MG63 CGRPR using a selective agonist of the putative CGRPR2, [Cys(Acm)(2,7)]CGRP, and a relatively specific antagonist of CGRPR1, CGRP(8-37). [Cys(Acm)(2,7)]CGRP acted as a significant agonist only upon ERK dephosphorylation, whereas this analog effectively antagonized CGRP-induced cAMP production and phosphorylation of cAMP response element-binding protein (CREB) and p38 MAPK. Although it had no agonistic action when used alone, CGRP(8-37) potently blocked CGRP actions on cAMP, CREB, and p38 MAPK but had less of an effect on ERK. Schild plot analysis of the latter data revealed that the apparent pA2 value for ERK is clearly distinguishable from those of the other three plots as judged using the 95% confidence intervals. Additional assays using 3-isobutyl-1-methylxanthine or the PKA inhibitor N-(2-[p-bromocinnamylamino]ethyl)-5-isoquinolinesulfonamide hydrochloride (H-89) indicated that the cAMP-dependent pathway was predominantly responsible for CREB phosphorylation, partially involved in ERK dephosphorylation, and not involved in p38 MAPK phosphorylation. Considering previous data from Scatchard analysis of [125I]CGRP binding in connection with these results, these findings suggest that MG63 cells possess two functionally distinct CGRPR subtypes that show almost identical affinity for CGRP but different sensitivity to CGRP analogs: one is best characterized as a variation of CGRPR1, and the second may be a novel variant of CGRPR2.

Database-Guided Discovery of Potent Peptides to Combat HIV-1 or Superbugs

Directory of Open Access Journals (Sweden)

Guangshun Wang

2013-05-01

Full Text Available Antimicrobial peptides (AMPs, small host defense proteins, are indispensable for the protection of multicellular organisms such as plants and animals from infection. The number of AMPs discovered per year increased steadily since the 1980s. Over 2,000 natural AMPs from bacteria, protozoa, fungi, plants, and animals have been registered into the antimicrobial peptide database (APD. The majority of these AMPs (>86% possess 11–50 amino acids with a net charge from 0 to +7 and hydrophobic percentages between 31–70%. This article summarizes peptide discovery on the basis of the APD. The major methods are the linguistic model, database screening, de novo design, and template-based design. Using these methods, we identified various potent peptides against human immunodeficiency virus type 1 (HIV-1 or methicillin-resistant Staphylococcus aureus (MRSA. While the stepwise designed anti-HIV peptide is disulfide-linked and rich in arginines, the ab initio designed anti-MRSA peptide is linear and rich in leucines. Thus, there are different requirements for antiviral and antibacterial peptides, which could kill pathogens via different molecular targets. The biased amino acid composition in the database-designed peptides, or natural peptides such as θ-defensins, requires the use of the improved two-dimensional NMR method for structural determination to avoid the publication of misleading structure and dynamics. In the case of human cathelicidin LL-37, structural determination requires 3D NMR techniques. The high-quality structure of LL-37 provides a solid basis for understanding its interactions with membranes of bacteria and other pathogens. In conclusion, the APD database is a comprehensive platform for storing, classifying, searching, predicting, and designing potent peptides against pathogenic bacteria, viruses, fungi, parasites, and cancer cells.

Development and use of engineered peptide deformylase in chemoenzymatic peptide synthesis

NARCIS (Netherlands)

Di Toma, Claudia

2012-01-01

Deze thesis beschrijft het onderzoek naar potentieel van het gebruik van het peptide deformylase (PDF) in chemo enzymatische peptide synthese. PDF is geschikt voor selective N terminale deformylatie van bepaalde N-formyl-peptides zonder gelijktijdige hydrolyse van de peptide binding. Door de

Partial agonist therapy in schizophrenia: relevance to diminished criminal responsibility.

Science.gov (United States)

Gavaudan, Gilles; Magalon, David; Cohen, Julien; Lançon, Christophe; Léonetti, Georges; Pélissier-Alicot, Anne-Laure

2010-11-01

Pathological gambling (PG), classified in the DSM-IV among impulse control disorders, is defined as inappropriate, persistent gaming for money with serious personal, family, and social consequences. Offenses are frequently committed to obtain money for gambling. Pathological gambling, a planned and structured behavioral disorder, has often been described as a complication of dopamine agonist treatment in patients with Parkinson's disease. It has never been described in patients with schizophrenia receiving dopamine agonists. We present two patients with schizophrenia, previously treated with antipsychotic drugs without any suggestion of PG, who a short time after starting aripiprazole, a dopamine partial agonist, developed PG and criminal behavior, which totally resolved when aripiprazole was discontinued. Based on recent advances in research on PG and adverse drug reactions to dopamine agonists in Parkinson's disease, we postulate a link between aripiprazole and PG in both our patients with schizophrenia and raise the question of criminal responsibility. © 2010 American Academy of Forensic Sciences.

Antibodies against linear epitopes on Goodpasture autoantigen in patients with anti-neutrophil cytoplasmic antibody-associated vasculitis.

Science.gov (United States)

Jia, Xiao-Yu; Yu, Jun-Tao; Hu, Shui-Yi; Li, Jian-Nan; Wang, Miao; Wang, Chen; Chen, Min; Cui, Zhao; Zhao, Ming-Hui

2017-09-01

In a substantial number of patients with crescentic glomerulonephritis, both anti-glomerular basement membrane (GBM) antibodies and anti-neutrophil cytoplasmic antibodies (ANCA) are detected simultaneously. ANCA is presumed to be the initial event but the mechanism is unknown. In the present study, we investigated the antibodies against linear epitopes on Goodpasture autoantigen in sera from patients with ANCA-associated vasculitis, aiming to reveal the mechanisms of the coexistence of the two kinds of autoantibodies. Thirty-one patients with ANCA-associated vasculitis were enrolled in this study. Twenty-four overlapping linear peptides were synthesized across the whole sequence of Goodpasture autoantigen. Serum antibodies against linear peptides were detected by ELISA and their associations with clinical features were further analyzed. Twenty-five out of the thirty-one (80.6%) sera from patients with ANCA-associated vasculitis possessed antibodies against linear peptides on Goodpasture autoantigen. These antibodies could be detected in 50% of patients with normal renal function (Scr ≤ 133 μmol/L), 70% of patients with moderate renal dysfunction (133 μmol/L  600 μmol/L) (P = 0.032). The highest recognition frequencies were found for peptides P4 (51.6%), P14 (54.8%), and P24 (54.8%), which contained the sequences that constitute the conformational epitopes of E A (P4) and E B (P14) recognized by anti-GBM antibodies. The level of anti-P4 antibodies was positively correlated with the percentage of crescents in glomeruli (r = 0.764, P = 0.027). Patients with anti-P24 antibodies had a significantly higher prevalence of renal dysfunction on diagnosis (88.2 vs. 42.9%, P = 0.018). Antibodies against linear epitopes on Goodpasture autoantigen could be detected in sera of patients with ANCA-associated vasculitis, which might mediate the production of antibodies towards the conformational epitopes on Goodpasture autoantigen, namely, the anti-GBM antibodies.

Membrane interaction and secondary structure of de novo designed arginine-and tryptophan peptides with dual function

KAUST Repository

Rydberg, Hanna A.

2012-10-01

Cell-penetrating peptides and antimicrobial peptides are two classes of positively charged membrane active peptides with several properties in common. The challenge is to combine knowledge about the membrane interaction mechanisms and structural properties of the two classes to design peptides with membrane-specific actions, useful either as transporters of cargo or as antibacterial substances. Membrane active peptides are commonly rich in arginine and tryptophan. We have previously designed a series of arg/trp peptides and investigated how the position and number of tryptophans affect cellular uptake. Here we explore the antimicrobial properties and the interaction with lipid model membranes of these peptides, using minimal inhibitory concentrations assay (MIC), circular dichroism (CD) and linear dichroism (LD). The results show that the arg/trp peptides inhibit the growth of the two gram positive strains Staphylococcus aureus and Staphylococcus pyogenes, with some individual variations depending on the position of the tryptophans. No inhibition of the gram negative strains Proteus mirabilis or Pseudomonas aeruginosa was noticed. CD indicated that when bound to lipid vesicles one of the peptides forms an α-helical like structure, whereas the other five exhibited rather random coiled structures. LD indicated that all six peptides were somehow aligned parallel with the membrane surface. Our results do not reveal any obvious connection between membrane interaction and antimicrobial effect for the studied peptides. By contrast cell-penetrating properties can be coupled to both the secondary structure and the degree of order of the peptides. © 2012 Elsevier Inc.

Physiologically-Relevant Modes of Membrane Interactions by the Human Antimicrobial Peptide, LL-37, Revealed by SFG Experiments

Science.gov (United States)

Ding, Bei; Soblosky, Lauren; Nguyen, Khoi; Geng, Junqing; Yu, Xinglong; Ramamoorthy, Ayyalusamy; Chen, Zhan

2013-05-01

Antimicrobial peptides (AMPs) could become the next generation antibiotic compounds which can overcome bacterial resistance by disrupting cell membranes and it is essential to determine the factors underlying its mechanism of action. Although high-resolution NMR and other biological studies have provided valuable insights, it has been a major challenge to follow the AMP-membrane interactions at physiologically-relevant low peptide concentrations. In this study, we demonstrate a novel approach to overcome this major limitation by performing Sum Frequency Generation (SFG) vibrational spectroscopic experiments on lipid bilayers containing an AMP, LL-37. Our results demonstrate the power of SFG to study non-linear helical peptides and also infer that lipid-peptide interaction and the peptide orientation depend on the lipid membrane composition. The observed SFG signal changes capture the aggregating process of LL-37 on membrane. In addition, our SFG results on cholesterol-containing lipid bilayers indicate the inhibition effect of cholesterol on peptide-induced membrane permeation process.

Urinary C-peptide: a useful tool for evaluating the endogenous insulin reserve in cohort and longitudinal studies of diabetes in childhood.

Science.gov (United States)

de Beaufort, C E; den Boer, N C; Bruining, G J; Eilers, G A; van Strik, R; Weterings, T

1988-09-01

Increasing research into the remission phase of type I diabetes mellitus stresses the importance of a non-traumatic and reliable method for the evaluation of endogenous insulin production. We compared 24-h urinary C-peptide excretion (UCE) with plasma C-peptide values before and after stimulation with 1 mg glucagon in 24 type I diabetic children. Fasting plasma C-peptide values and stimulated plasma C-peptide values showed a linear correlation with 24 h UCE. Mean plasma C-peptide levels correlated inversely with the exogenous insulin dose. A slightly better correlation was found between the exogenous insulin dose and 24 h UCE. Control data of 24 h UCE were obtained from healthy siblings. A linear correlation with age was found up to 10 years of age above which UCE values seem to reach a plateau. This effect of age, as well as the frequency of sampling was taken into account in the derivation of 95% reference intervals for UCE. The measurement of 24 h UCE appears to be a useful parameter to assess endogenous insulin production in diabetic children, provided that age is taken into account.

Disposable pencil graphite electrode modified with peptide nanotubes for Vitamin B12 analysis

International Nuclear Information System (INIS)

Pala, Betül Bozdoğan; Vural, Tayfun; Kuralay, Filiz; Çırak, Tamer; Bolat, Gülçin; Abacı, Serdar; Denkbaş, Emir Baki

2014-01-01

In this study, peptide nanostructures from diphenylalanine were synthesized in various solvents with various polarities and characterized with Scanning Electron Microscopy (SEM) and Powder X-ray Diffraction (PXRD) techniques. Formation of peptide nanofibrils, nanovesicles, nanoribbons, and nanotubes was observed in different solvent mediums. In order to investigate the effects of peptide nanotubes (PNT) on electrochemical behavior of disposable pencil graphite electrodes (PGE), electrode surfaces were modified with fabricated peptide nanotubes. Electrochemical activity of the pencil graphite electrode was increased with the deposition of PNTs on the surface. The effects of the solvent type, the peptide nanotube concentration, and the passive adsorption time of peptide nanotubes on pencil graphite electrode were studied. For further electrochemical studies, electrodes were modified for 30 min by immobilizing PNTs, which were prepared in water at 6 mg/mL concentration. Vitamin B 12 analyses were performed by the Square Wave (SW) voltammetry method using modified PGEs. The obtained data showed linearity over the range of 0.2 μM and 9.50 μM Vitamin B 12 concentration with high sensitivity. Results showed that PNT modified PGEs were highly simple, fast, cost effective, and feasible for the electro-analytical determination of Vitamin B 12 in real samples.

Effect of GLP-1 receptor agonist treatment on body weight in obese antipsychotic-treated patients with schizophrenia

DEFF Research Database (Denmark)

Ishøy, Pelle L; Knop, Filip K; Broberg, Brian V

2017-01-01

and placebo groups experienced significant ( P  = .004), however similar ( P  = .98), weight losses of 2.24 ± 3.3 and 2.23 ± 4.4 kg, respectively, after 3 months of treatment. CONCLUSIONS: Treatment with exenatide once-weekly did not promote weight loss in obese, antipsychotic-treated patients......AIMS: Schizophrenia is associated with cardiovascular co-morbidity and a reduced life-expectancy of up to 20 years. Antipsychotics are dopamine D2 receptor antagonists and are the standard of medical care in schizophrenia, but the drugs are associated with severe metabolic side effects...... such as obesity and diabetes. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are registered for treatment of both obesity and type 2 diabetes. We investigated metabolic effects of the GLP-1RA, exenatide once-weekly, in non-diabetic, antipsychotic-treated, obese patients with schizophrenia. MATERIAL...

Functional characterization of the modified melanocortin peptides responsible for ligand selectivity at the human melanocortin receptors.

Science.gov (United States)

Chen, Min; Georgeson, Keith E; Harmon, Carroll M; Haskell-Luevano, Carrie; Yang, Yingkui

2006-11-01

The melanocortin system plays an important role in energy homeostasis as well as skin pigmentation, steroidogenesis and exocrine gland function. In this study, we examined eight Ac-His-Phe-Arg-Trp-NH(2) tetrapeptides that were modified at the Phe position and pharmacologically characterized their activities at the human MCR wild-types and their mutants. Our results indicate that at the hMC1R, all D stereochemical modified residues at the Phe position of peptides increase cAMP production in a dose-dependent manner. At the hMC3R, the DPhe peptide dose dependently increases cAMP production but all other three tetrapeptides were not. At the hMC4R, both the DPhe and DNal(1') peptides induce cAMP production. However, both DTyr and DNal(2') were not able to induce cAMP production. Further studies indicated that at the hMC1R M128L mutant receptor, the all D-configured tetrapeptides reduce their potencies as compared to that of hMC1R wild-type. However, at the hMC3R and hMC4R L165M and L133M mutant receptors, the DNal(2') and DTyr tetrapeptides possess agonist activity. These findings indicate that DPhe in tetrapeptide plays an important role in ligand selectivity and specific residue TM3 of the melanocortin receptors is crucial for ligand selectivity.

New dendrimer - Peptide host - Guest complexes: Towards dendrimers as peptide carriers

DEFF Research Database (Denmark)

Boas, Ulrik; Sontjens, S.H.M.; Jensen, Knud Jørgen

2002-01-01

Adamantyl urea and adamantyl thiourea modified poly(propylene imine) dendrimers act as hosts for N-terminal tert-butoxycarbonyl (Boc)-protected peptides and form chloroform-soluble complexes. investigations with NMR spectroscopy show that the peptide is bound to the dendrimer by ionic interactions...... between the dendrimer outer shell tertiary amines and the C-terminal carboxylic acid of the peptide, and also through host-urea to peptide-amide hydrogen bonding. The hydrogen-bonding nature of the peptide dendrimer interactions was further confirmed by using Fourier transform IR spectroscopy, for which...... the NH- and CO-stretch signals of the peptide amide moieties shift towards lower wave-numbers upon complexation with the dendrimer. Spatial analysis of the complexes with NOESY spectroscopy generally shows close proximity of the N-terminal Boc group of the peptide to the peripheral adamantyl groups...

Effect of beta-agonists on LAM progression and treatment.

Science.gov (United States)

Le, Kang; Steagall, Wendy K; Stylianou, Mario; Pacheco-Rodriguez, Gustavo; Darling, Thomas N; Vaughan, Martha; Moss, Joel

2018-01-30

Lymphangioleiomyomatosis (LAM), a rare disease of women, is associated with cystic lung destruction resulting from the proliferation of abnormal smooth muscle-like LAM cells with mutations in the tuberous sclerosis complex (TSC) genes TSC1 and/or TSC2 The mutant genes and encoded proteins are responsible for activation of the mechanistic target of rapamycin (mTOR), which is inhibited by sirolimus (rapamycin), a drug used to treat LAM. Patients who have LAM may also be treated with bronchodilators for asthma-like symptoms due to LAM. We observed stabilization of forced expiratory volume in 1 s over time in patients receiving sirolimus and long-acting beta-agonists with short-acting rescue inhalers compared with patients receiving only sirolimus. Because beta-agonists increase cAMP and PKA activity, we investigated effects of PKA activation on the mTOR pathway. Human skin TSC2 +/- fibroblasts or LAM lung cells incubated short-term with isoproterenol (beta-agonist) showed a sirolimus-independent increase in phosphorylation of S6, a downstream effector of the mTOR pathway, and increased cell growth. Cells incubated long-term with isoproterenol, which may lead to beta-adrenergic receptor desensitization, did not show increased S6 phosphorylation. Inhibition of PKA blocked the isoproterenol effect on S6 phosphorylation. Thus, activation of PKA by beta-agonists increased phospho-S6 independent of mTOR, an effect abrogated by beta-agonist-driven receptor desensitization. In agreement, retrospective clinical data from patients with LAM suggested that a combination of bronchodilators in conjunction with sirolimus may be preferable to sirolimus alone for stabilization of pulmonary function.

Glucagon-like peptide-1 (GLP-1) and the regulation of human invariant natural killer T cells: lessons from obesity, diabetes and psoriasis.

LENUS (Irish Health Repository)

Hogan, A E

2011-11-01

The innate immune cells, invariant natural killer T cells (iNKT cells), are implicated in the pathogenesis of psoriasis, an inflammatory condition associated with obesity and other metabolic diseases, such as diabetes and dyslipidaemia. We observed an improvement in psoriasis severity in a patient within days of starting treatment with an incretin-mimetic, glucagon-like peptide-1 (GLP-1) receptor agonist. This was independent of change in glycaemic control. We proposed that this unexpected clinical outcome resulted from a direct effect of GLP-1 on iNKT cells.

Utilization Patterns of Glucagon-Like Peptide-1 Receptor Agonists in Patients with Type 2 Diabetes Mellitus in Italy: A Retrospective Cohort Study.

Science.gov (United States)

Federici, Marco Orsini; McQuillan, Janette; Biricolti, Giovanni; Losi, Serena; Lebrec, Jeremie; Richards, Catrina; Miglio, Cristiana; Norrbacka, Kirsi

2018-04-01

Real-world evidence on glucagon-like peptide-1 receptor agonist (GLP-1 RAs) usage is emerging in different European countries but is lacking in Italy. This retrospective cohort study aimed to describe the real-world drug utilization patterns in patients initiating GLP-1 RAs for treating T2DM in Italy. Adults aged ≥ 20 years and with ≥ 1 oral antidiabetic drug (alone or in combination with insulin) other than GLP-1 RAs in the 6 months prior to initiating exenatide twice daily (exBID), exenatide once weekly (exQW), dulaglutide once weekly (DULA), liraglutide once daily (LIRA) or lixisenatide once daily (LIXI) between March and July 2016 were retrospectively identified in the Italian IMS LifeLink™ longitudinal prescriptions database (retail pharmacy data). Patients with ≥ 6-month follow-up (defined as evidence of any prescription activity) were included. Proportions of patients who remained persistent (continued treatment until discontinuation/switch) in the first 6 months and of those who discontinued or switched to a different GLP-1 RA over the entire follow-up were recorded. For each treatment, the average daily/weekly dosage (ADD/AWD) while persistent during the available follow-up was calculated. We identified 7319 patients: 92 exBID, 970 exQW, 3368 DULA, 2573 LIRA and 316 LIXI. Across treatments, 89% patients were ≥ 50 years old, 54% were males, and the median follow-up duration ranged between 8.1 and 8.7 months. At 6 months, 35% exBID, 47% exQW, 62% DULA, 50% LIRA and 40% LIXI patients remained persistent. Over the entire follow-up, median persistence days varied from 73 (exBID) to > 300 days (DULA). The mean ± SD ADD/AWD was exBID: 17.7 ± 2.1 µg/day; exQW: 2.1 ± 0.1 mg/week; DULA: 1.5 ± 0.2 mg/week; LIRA: 1.5 ± 0.2 mg/day; LIXI: 21.0 ± 5.5 µg/day. This real-world analysis suggests differences exist in persistence between patients treated with various GLP-1 RAs. Among the investigated

Amide I SFG Spectral Line Width Probes the Lipid-Peptide and Peptide-Peptide Interactions at Cell Membrane In Situ and in Real Time.

Science.gov (United States)

Zhang, Baixiong; Tan, Junjun; Li, Chuanzhao; Zhang, Jiahui; Ye, Shuji

2018-06-13

The balance of lipid-peptide and peptide-peptide interactions at cell membrane is essential to a large variety of cellular processes. In this study, we have experimentally demonstrated for the first time that sum frequency generation vibrational spectroscopy can be used to probe the peptide-peptide and lipid-peptide interactions in cell membrane in situ and in real time by determination of the line width of amide I band of protein backbone. Using a "benchmark" model of α-helical WALP23, it is found that the dominated lipid-peptide interaction causes a narrow line width of the amide I band, whereas the peptide-peptide interaction can markedly broaden the line width. When WALP23 molecules insert into the lipid bilayer, a quite narrow line width of the amide I band is observed because of the lipid-peptide interaction. In contrast, when the peptide lies down on the bilayer surface, the line width of amide I band becomes very broad owing to the peptide-peptide interaction. In terms of the real-time change in the line width, the transition from peptide-peptide interaction to lipid-peptide interaction is monitored during the insertion of WALP23 into 1,2-dipalmitoyl- sn-glycero-3-phospho-(1'- rac-glycerol) (DPPG) lipid bilayer. The dephasing time of a pure α-helical WALP23 in 1-palmitoyl-2-oleoyl- sn-glycero-3-phospho-(1'- rac-glycerol) and DPPG bilayer is determined to be 2.2 and 0.64 ps, respectively. The peptide-peptide interaction can largely accelerate the dephasing time.

SVMTriP: a method to predict antigenic epitopes using support vector machine to integrate tri-peptide similarity and propensity.

Directory of Open Access Journals (Sweden)

Bo Yao

Full Text Available Identifying protein surface regions preferentially recognizable by antibodies (antigenic epitopes is at the heart of new immuno-diagnostic reagent discovery and vaccine design, and computational methods for antigenic epitope prediction provide crucial means to serve this purpose. Many linear B-cell epitope prediction methods were developed, such as BepiPred, ABCPred, AAP, BCPred, BayesB, BEOracle/BROracle, and BEST, towards this goal. However, effective immunological research demands more robust performance of the prediction method than what the current algorithms could provide. In this work, a new method to predict linear antigenic epitopes is developed; Support Vector Machine has been utilized by combining the Tri-peptide similarity and Propensity scores (SVMTriP. Applied to non-redundant B-cell linear epitopes extracted from IEDB, SVMTriP achieves a sensitivity of 80.1% and a precision of 55.2% with a five-fold cross-validation. The AUC value is 0.702. The combination of similarity and propensity of tri-peptide subsequences can improve the prediction performance for linear B-cell epitopes. Moreover, SVMTriP is capable of recognizing viral peptides from a human protein sequence background. A web server based on our method is constructed for public use. The server and all datasets used in the current study are available at http://sysbio.unl.edu/SVMTriP.

Biosynthesis of amidated joining peptide from pro-adrenocorticotropin-endorphin

Energy Technology Data Exchange (ETDEWEB)

Cullen, E.I.; Mains, R.E. (Johns Hopkins Univ. School of Medicine, Baltimore, MD (USA))

1987-09-01

Joining peptide is the major alpha-amidated product of pro-ACTH/endorphin (PAE) in AtT-20 corticotropic tumor cells. To study intracellular joining peptide synthesis, affinity purified antibodies directed against gamma-MSH, joining peptide, and ACTH were used to immunoprecipitate extracts from biosynthetically labeled AtT-20 cells. Immunoprecipitates were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by tryptic peptide mapping on HPLC. In steady labeling experiments, radioactivity in amidated joining peptide (JP) increased roughly linearly with time, in the manner of a final product, whereas radioactivity associated with PAE (1-94)NH2 reached a constant value after 2-4 h, indicating that PAE(1-94)NH2 is an intermediate in the biosynthesis of JP. Radioactivity appeared in ACTH(1-39) well before JP, consistent with a cleavage order in which ACTH is cleaved from PAE(1-95) before JP sequences are cleaved from PAE(1-74). This conclusion was supported by tryptic peptide analyses of immunoprecipitates, which indicated that less than 5% of JP-related material is cleaved from PAE(1-74) before being cleaved from ACTH-related sequences. After a pulse label, radioactivity in PAE(1-94)NH2 reached a peak value after 1 h of chase and declined with a half-life of less than 1 h. Amidated JP increased to a constant level after 2 h of chase. Enough radiolabeled PAE(1-94)NH2 was detected to account for about half of the radioactivity found in amidated JP, indicating that about half of JP-related material is first cleaved from PAE(1-95) before being amidated. This result was corroborated using HPLC purification to determine both amidated and glycine-extended forms of JP.

Biosynthesis of amidated joining peptide from pro-adrenocorticotropin-endorphin

International Nuclear Information System (INIS)

Cullen, E.I.; Mains, R.E.

1987-01-01

Joining peptide is the major alpha-amidated product of pro-ACTH/endorphin (PAE) in AtT-20 corticotropic tumor cells. To study intracellular joining peptide synthesis, affinity purified antibodies directed against gamma-MSH, joining peptide, and ACTH were used to immunoprecipitate extracts from biosynthetically labeled AtT-20 cells. Immunoprecipitates were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and by tryptic peptide mapping on HPLC. In steady labeling experiments, radioactivity in amidated joining peptide (JP) increased roughly linearly with time, in the manner of a final product, whereas radioactivity associated with PAE (1-94)NH2 reached a constant value after 2-4 h, indicating that PAE(1-94)NH2 is an intermediate in the biosynthesis of JP. Radioactivity appeared in ACTH(1-39) well before JP, consistent with a cleavage order in which ACTH is cleaved from PAE(1-95) before JP sequences are cleaved from PAE(1-74). This conclusion was supported by tryptic peptide analyses of immunoprecipitates, which indicated that less than 5% of JP-related material is cleaved from PAE(1-74) before being cleaved from ACTH-related sequences. After a pulse label, radioactivity in PAE(1-94)NH2 reached a peak value after 1 h of chase and declined with a half-life of less than 1 h. Amidated JP increased to a constant level after 2 h of chase. Enough radiolabeled PAE(1-94)NH2 was detected to account for about half of the radioactivity found in amidated JP, indicating that about half of JP-related material is first cleaved from PAE(1-95) before being amidated. This result was corroborated using HPLC purification to determine both amidated and glycine-extended forms of JP

Rational design and application of responsive α-helical peptide hydrogels

Science.gov (United States)

Banwell, Eleanor F.; Abelardo, Edgardo S.; Adams, Dave J.; Birchall, Martin A.; Corrigan, Adam; Donald, Athene M.; Kirkland, Mark; Serpell, Louise C.; Butler, Michael F.; Woolfson, Derek N.

2009-01-01

Biocompatible hydrogels have a wide variety of potential applications in biotechnology and medicine, such as the controlled delivery and release of cells, cosmetics and drugs; and as supports for cell growth and tissue engineering1. Rational peptide design and engineering are emerging as promising new routes to such functional biomaterials2-4. Here we present the first examples of rationally designed and fully characterized self-assembling hydrogels based on standard linear peptides with purely α-helical structures, which we call hydrogelating self-assembling fibres (hSAFs). These form spanning networks of α-helical fibrils that interact to give self-supporting physical hydrogels of >99% water content. The peptide sequences can be engineered to alter the underlying mechanism of gelation and, consequently, the hydrogel properties. Interestingly, for example, those with hydrogen-bonded networks melt upon heating, whereas those formed via hydrophobic interactions strengthen when warmed. The hSAFs are dual-peptide systems that only gel on mixing, which gives tight control over assembly5. These properties raise possibilities for using the hSAFs as substrates in cell culture. We have tested this in comparison with the widely used Matrigel substrate, and demonstrate that, like Matrigel, hSAFs support both growth and differentiation of rat adrenal pheochromocytoma cells for sustained periods in culture. PMID:19543314

The Good, the Bad, and the Ugly: Agonistic Behaviour in Juvenile Crocodilians

OpenAIRE

Brien, Matthew L.; Lang, Jeffrey W.; Webb, Grahame J.; Stevenson, Colin; Christian, Keith A.

2013-01-01

We examined agonistic behaviour in seven species of hatchling and juvenile crocodilians held in small groups (N = 4) under similar laboratory conditions. Agonistic interactions occurred in all seven species, typically involved two individuals, were short in duration (5-15 seconds), and occurred between 1600-2200 h in open water. The nature and extent of agonistic interactions, the behaviours displayed, and the level of conspecific tolerance varied among species. Discrete postures, non-contact...

Prolonging survival of corneal transplantation by selective sphingosine-1-phosphate receptor 1 agonist.

Directory of Open Access Journals (Sweden)

Min Gao

Full Text Available Corneal transplantation is the most used therapy for eye disorders. Although the cornea is somewhat an immune privileged organ, immune rejection is still the major problem that reduces the success rate. Therefore, effective chemical drugs that regulate immunoreactions are needed to improve the outcome of corneal transplantations. Here, a sphingosine-1-phosphate receptor 1 (S1P1 selective agonist was systematically evaluated in mouse allogeneic corneal transplantation and compared with the commonly used immunosuppressive agents. Compared with CsA and the non-selective sphingosine 1-phosphate (S1P receptor agonist FTY720, the S1P1 selective agonist can prolong the survival corneal transplantation for more than 30 days with a low immune response. More importantly, the optimal dose of the S1P1 selective agonist was much less than non-selective S1P receptor agonist FTY720, which would reduce the dose-dependent toxicity in drug application. Then we analyzed the mechanisms of the selected S1P1 selective agonist on the immunosuppression. The results shown that the S1P1 selective agonist could regulate the distribution of the immune cells with less CD4+ T cells and enhanced Treg cells in the allograft, moreover the expression of anti-inflammatory cytokines TGF-β1 and IL-10 unregulated which can reduce the immunoreactions. These findings suggest that S1P1 selective agonist may be a more appropriate immunosuppressive compound to effectively prolong mouse allogeneic corneal grafts survival.

Taylor Dispersion Analysis as a promising tool for assessment of peptide-peptide interactions.

Science.gov (United States)

Høgstedt, Ulrich B; Schwach, Grégoire; van de Weert, Marco; Østergaard, Jesper

2016-10-10

Protein-protein and peptide-peptide (self-)interactions are of key importance in understanding the physiochemical behavior of proteins and peptides in solution. However, due to the small size of peptide molecules, characterization of these interactions is more challenging than for proteins. In this work, we show that protein-protein and peptide-peptide interactions can advantageously be investigated by measurement of the diffusion coefficient using Taylor Dispersion Analysis. Through comparison to Dynamic Light Scattering it was shown that Taylor Dispersion Analysis is well suited for the characterization of protein-protein interactions of solutions of α-lactalbumin and human serum albumin. The peptide-peptide interactions of three selected peptides were then investigated in a concentration range spanning from 0.5mg/ml up to 80mg/ml using Taylor Dispersion Analysis. The peptide-peptide interactions determination indicated that multibody interactions significantly affect the PPIs at concentration levels above 25mg/ml for the two charged peptides. Relative viscosity measurements, performed using the capillary based setup applied for Taylor Dispersion Analysis, showed that the viscosity of the peptide solutions increased with concentration. Our results indicate that a viscosity difference between run buffer and sample in Taylor Dispersion Analysis may result in overestimation of the measured diffusion coefficient. Thus, Taylor Dispersion Analysis provides a practical, but as yet primarily qualitative, approach to assessment of the colloidal stability of both peptide and protein formulations. Copyright © 2016 Elsevier B.V. All rights reserved.

Urinary osteocalcin and serum pro-C-type natriuretic peptide predict linear catch-up growth in infants

DEFF Research Database (Denmark)

Kilpeläinen, Leena; Ivaska, Kaisa K; Kuiri-Hänninen, Tanja

2012-01-01

of this longitudinal study was to determine the extent to which postnatal levels of circulating cartilage (serum pro-C-type natriuretic peptide [S-proCNP]) and urinary bone metabolic markers (urinary osteocalcin [MidOC] and two forms of C-terminal cross-linked telopeptide of type I collagen [U-α-CTX-I and U...

Neuroprotective Mechanisms of Glucagon-like Peptide-1-based Therapies in Ischaemic Stroke

DEFF Research Database (Denmark)

Marlet, Ida R; Ölmestig, Joakim N E; Vilsbøll, Tina

2018-01-01

Review was to systematically evaluate the proposed mechanism of action for GLP-1-based therapies in ischaemic brain damage in animals. We performed a literature search using MEDLINE, EMBASE and The Cochrane Library. GLP-1-based therapies administered before, during or after experimental stroke in diabetic and non......Glucagon-like peptide-1 (GLP-1)-based therapies, GLP-1 receptor agonists (GLP-1RAs) and dipeptidyl peptidase-4 inhibitors (DPP-4Is) are widely used for the treatment of type 2 diabetes. Increasing evidence suggests that they may provide neuroprotection. The aim of this Mini......-diabetic animals were evaluated. We reviewed 27 studies comprised of 20 involving GLP-1RAs and seven involving DPP-4Is. Both GLP-1RAs and DPP-4Is affected the acute inflammatory response secondary to ischaemia by reducing inflammation, endothelial leakage and excitotoxicity. Both treatments also reduced oxidative...

Long-acting beta 2-agonists in chronic obstructive pulmonary disease.

Science.gov (United States)

Llewellyn-Jones, Carol

2002-01-01

Until recently, the use of long-acting beta 2-agonists in chronic obstructive pulmonary disease has been understated. There is now evidence that they may offer benefits beyond bronchodilation. This article reviews the management of chronic obstructive pulmonary disease and looks at the place of long-acting beta 2-agonists as a first-line treatment option.

Non-Acidic Free Fatty Acid Receptor 4 Agonists with Antidiabetic Activity

DEFF Research Database (Denmark)

Goncalves de Azavedo, Carlos M. B. P.; Watterson, Kenneth R; Wargent, Ed T

2016-01-01

The free fatty acid receptor 4 (FFA4 or GPR120) has appeared as an interesting potential target for the treatment of metabolic disorders. At present, most FFA4 ligands are carboxylic acids that are assumed to mimic the endogenous long-chain fatty acid agonists. Here, we report preliminary structure......-activity relationship studies of a previously disclosed non-acidic sulfonamide FFA4 agonist. Mutagenesis studies indicate that the compounds are orthosteric agonists despite the absence of a carboxylate function. The preferred compounds showed full agonist activity on FFA4 and complete selectivity over FFA1, although...... a significant fraction of these non-carboxylic acids also showed partial antagonistic activity on FFA1. Studies in normal and diet-induced obese (DIO) mice with the preferred compound 34 showed improved glucose tolerance after oral dosing in an oral glucose tolerance test. Chronic dosing of 34 in DIO mice...

Biological effects of a de novo designed myxoma virus peptide analogue: evaluation of cytotoxicity on tumor cells.

Directory of Open Access Journals (Sweden)

Taghrid S Istivan

Full Text Available BACKGROUND: The Resonant Recognition Model (RRM is a physico-mathematical model that interprets protein sequence linear information using digital signal processing methods. In this study the RRM concept was employed for structure-function analysis of myxoma virus (MV proteins and the design of a short bioactive therapeutic peptide with MV-like antitumor/cytotoxic activity. METHODOLOGY/PRINCIPAL FINDINGS: The analogue RRM-MV was designed by RRM as a linear 18 aa 2.3 kDa peptide. The biological activity of this computationally designed peptide analogue against cancer and normal cell lines was investigated. The cellular cytotoxicity effects were confirmed by confocal immunofluorescence microscopy, by measuring the levels of cytoplasmic lactate dehydrogenase (LDH and by Prestoblue cell viability assay for up to 72 hours in peptide treated and non-treated cell cultures. Our results revealed that RRM-MV induced a significant dose and time-dependent cytotoxic effect on murine and human cancer cell lines. Yet, when normal murine cell lines were similarly treated with RRM-MV, no cytotoxic effects were observed. Furthermore, the non-bioactive RRM designed peptide RRM-C produced negligible cytotoxic effects on these cancer and normal cell lines when used at similar concentrations. The presence/absence of phosphorylated Akt activity in B16F0 mouse melanoma cells was assessed to indicate the possible apoptosis signalling pathway that could be affected by the peptide treatment. So far, Akt activity did not seem to be significantly affected by RRM-MV as is the case for the original viral protein. CONCLUSIONS/SIGNIFICANCE: Our findings indicate the successful application of the RRM concept to design a bioactive peptide analogue (RRM-MV with cytotoxic effects on tumor cells only. This 2.345 kDa peptide analogue to a 49 kDa viral protein may be suitable to be developed as a potential cancer therapeutic. These results also open a new direction to the rational

Strong piezoelectricity in bioinspired peptide nanotubes.

Science.gov (United States)

Kholkin, Andrei; Amdursky, Nadav; Bdikin, Igor; Gazit, Ehud; Rosenman, Gil

2010-02-23

We show anomalously strong shear piezoelectric activity in self-assembled diphenylalanine peptide nanotubes (PNTs), indicating electric polarization directed along the tube axis. Comparison with well-known piezoelectric LiNbO(3) and lateral signal calibration yields sufficiently high effective piezoelectric coefficient values of at least 60 pm/V (shear response for tubes of approximately 200 nm in diameter). PNTs demonstrate linear deformation without irreversible degradation in a broad range of driving voltages. The results open up a wide avenue for developing new generations of "green" piezoelectric materials and piezonanodevices based on bioactive tubular nanostructures potentially compatible with human tissue.

Antimicrobial Peptides in 2014

Directory of Open Access Journals (Sweden)

Guangshun Wang

2015-03-01

Full Text Available This article highlights new members, novel mechanisms of action, new functions, and interesting applications of antimicrobial peptides reported in 2014. As of December 2014, over 100 new peptides were registered into the Antimicrobial Peptide Database, increasing the total number of entries to 2493. Unique antimicrobial peptides have been identified from marine bacteria, fungi, and plants. Environmental conditions clearly influence peptide activity or function. Human α-defensin HD-6 is only antimicrobial under reduced conditions. The pH-dependent oligomerization of human cathelicidin LL-37 is linked to double-stranded RNA delivery to endosomes, where the acidic pH triggers the dissociation of the peptide aggregate to release its cargo. Proline-rich peptides, previously known to bind to heat shock proteins, are shown to inhibit protein synthesis. A model antimicrobial peptide is demonstrated to have multiple hits on bacteria, including surface protein delocalization. While cell surface modification to decrease cationic peptide binding is a recognized resistance mechanism for pathogenic bacteria, it is also used as a survival strategy for commensal bacteria. The year 2014 also witnessed continued efforts in exploiting potential applications of antimicrobial peptides. We highlight 3D structure-based design of peptide antimicrobials and vaccines, surface coating, delivery systems, and microbial detection devices involving antimicrobial peptides. The 2014 results also support that combination therapy is preferred over monotherapy in treating biofilms.

VUV action spectroscopy of protonated leucine-enkephalin peptide in the 6-14 eV range

Energy Technology Data Exchange (ETDEWEB)

Ranković, M. Lj. [Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade (Serbia); Canon, F. [INRA, UMR1324 Centre des Sciences du Goût et de l’Alimentation, F-21000 Dijon (France); Nahon, L. [SOLEIL, l’Orme des Merisiers, St Aubin, BP48, 91192 Gif sur Yvette Cedex (France); Giuliani, A. [SOLEIL, l’Orme des Merisiers, St Aubin, BP48, 91192 Gif sur Yvette Cedex (France); INRA, UAR1008, CEPIA, Rue de la Géraudière, BP 71627, 44316 Nantes (France); Milosavljević, A. R., E-mail: vraz@ipb.ac.rs [Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade (Serbia); Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

2015-12-28

We have studied the Vacuum Ultraviolet (VUV) photodissociation of gas-phase protonated leucine-enkephalin peptide ion in the 5.7 to 14 eV photon energy range by coupling a linear quadrupole ion trap with a synchrotron radiation source. We report VUV activation tandem mass spectra at 6.7, 8.4, and 12.8 eV photon energies and photodissociation yields for a number of selected fragments. The obtained results provide insight into both near VUV radiation damage and electronic properties of a model peptide. We could distinguish several absorption bands and assign them to particular electronic transitions, according to previous theoretical studies. The photodissociation yields appear to be very different for the various observed fragmentation channels, depending on both the types of fragments and their position along the peptide backbone. The present results are discussed in light of recent gas-phase spectroscopic data on peptides.

Efficacy and Acceptability of Glycemic Control of Glucagon-Like Peptide-1 Receptor Agonists among Type 2 Diabetes: A Systematic Review and Network Meta-Analysis.

Directory of Open Access Journals (Sweden)

Zhixia Li

Full Text Available To synthesize current evidence of the impact of Glucagon-like peptide-1 receptor agonists (GLP-1 RAs on hypoglycemia, treatment discontinuation and glycemic level in patients with type 2 diabetes.Systematic review and network meta-analysis.Literature search (Medline, Embase, the Cochrane library, website of clinical trial, bibliographies of published systematic reviews.Randomized controlled trials with available data comparing GLP-1 RAs with placebo or traditional anti-diabetic drugs in patients with type 2 diabetes.Traditional pairwise meta-analyses within DerSimonian-Laird random effects model and network meta-analysis within a Bayesian framework were performed to calculate odds ratios for the incidence of hypoglycemia, treatment discontinuation, HbA1c<7.0% and HbA1c<6.5%. Ranking probabilities for all treatments were estimated to obtain a treatment hierarchy using the surface under the cumulative ranking curve (SUCRA and mean ranks.78 trials with 13 treatments were included. Overall, all GLP-1 RAs except for albiglutide increased the risk of hypoglycemia when compared to placebo. Reduction in the incidence of hypoglycemia was found for all GLP-1 RAs versus insulin (except for dulaglutide and sulphonylureas. For the incidence of treatment discontinuation, increase was found for exenatide, liraglutide, lixisenatide and taspoglutide versus placebo, insulin and sitagliptin. For glycemic level, decrease was found for all GLP-1 RAs versus placebo. Dulaglutide, exenatide long-acting release (exe_lar, liraglutide and taspoglutide had significant lowering effect when compared with sitagliptin (HbA1c<7.0% and insulin (HbA1c<6.5%. Finally, according to SUCRAs, placebo, thiazolidinediones and albiglutide had the best decrease effect on hypoglycemia; sulphanylureas, sitagliptin and insulin decrease the incidence of treatment discontinuation most; exe_lar and dulaglutide had the highest impact on glycemic level among 13 treatments.Among 13 treatments, GLP

The Protective Role of PAC1-Receptor Agonist Maxadilan in BCCAO-Induced Retinal Degeneration.

Science.gov (United States)

Vaczy, A; Reglodi, D; Somoskeoy, T; Kovacs, K; Lokos, E; Szabo, E; Tamas, A; Atlasz, T

2016-10-01

A number of studies have proven that pituitary adenylate cyclase activating polypeptide (PACAP) is protective in neurodegenerative diseases. Permanent bilateral common carotid artery occlusion (BCCAO) causes severe degeneration in the rat retina. In our previous studies, protective effects were observed with PACAP1-38, PACAP1-27, and VIP but not with their related peptides, glucagon, or secretin in BCCAO. All three PACAP receptors (PAC1, VPAC1, VPAC2) appear in the retina. Molecular and immunohistochemical analysis demonstrated that the retinoprotective effects are most probably mainly mediated by the PAC1 receptor. The aim of the present study was to investigate the retinoprotective effects of a selective PAC1-receptor agonist maxadilan in BCCAO-induced retinopathy. Wistar rats were used in the experiment. After performing BCCAO, the right eye was treated with intravitreal maxadilan (0.1 or 1 μM), while the left eye was injected with vehicle. Sham-operated rats received the same treatment. Two weeks after the operation, retinas were processed for standard morphometric and molecular analysis. Intravitreal injection of 0.1 or 1 μM maxadilan caused significant protection in the thickness of most retinal layers and the number of cells in the GCL compared to the BCCAO-operated eyes. In addition, 1 μM maxadilan application was more effective than 0.1 μM maxadilan treatment in the ONL, INL, IPL, and the entire retina (OLM-ILM). Maxadilan treatment significantly decreased cytokine expression (CINC-1, IL-1α, and L-selectin) in ischemia. In summary, our histological and molecular analysis showed that maxadilan, a selective PAC1 receptor agonist, has a protective role in BCCAO-induced retinal degeneration, further supporting the role of PAC1 receptor conveying the retinoprotective effects of PACAP.

Gastrin-Releasing Peptide and Glucose Metabolism Following Pancreatitis.

Science.gov (United States)

Pendharkar, Sayali A; Drury, Marie; Walia, Monika; Korc, Murray; Petrov, Maxim S

2017-08-01

Gastrin-releasing peptide (GRP) is a pluripotent peptide that has been implicated in both gastrointestinal inflammatory states and classical chronic metabolic diseases such as diabetes. Abnormal glucose metabolism (AGM) after pancreatitis, an exemplar inflammatory disease involving the gastrointestinal tract, is associated with persistent low-grade inflammation and altered secretion of pancreatic and gut hormones as well as cytokines. While GRP is involved in secretion of many of them, it is not known whether GRP has a role in AGM. Therefore, we aimed to investigate the association between GRP and AGM following pancreatitis. Fasting blood samples were collected to measure GRP, blood glucose, insulin, amylin, glucagon, pancreatic polypeptide (PP), somatostatin, cholecystokinin, gastric-inhibitory peptide (GIP), gastrin, ghrelin, glicentin, glucagon-like peptide-1 and 2, oxyntomodulin, peptide YY (PYY), secretin, vasoactive intestinal peptide, tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein (MCP)-1, and interleukin-6. Modified Poisson regression analysis and linear regression analyses were conducted. Four statistical models were used to adjust for demographic, metabolic, and pancreatitis-related risk factors. A total of 83 individuals after an episode of pancreatitis were recruited. GRP was significantly associated with AGM, consistently in all four models (P -trend < 0.05), and fasting blood glucose contributed 17% to the variance of GRP. Further, GRP was significantly associated with glucagon (P < 0.003), MCP-1 (P < 0.025), and TNF-α (P < 0.025) - consistently in all four models. GRP was also significantly associated with PP and PYY in three models (P < 0.030 for both), and with GIP and glicentin in one model (P = 0.001 and 0.024, respectively). Associations between GRP and other pancreatic and gut hormones were not significant. GRP is significantly increased in patients with AGM after pancreatitis and is associated with increased levels of pro

Preoperative weight loss with glucagon-like peptide-1 receptor agonist treatment predicts greater weight loss achieved by the combination of medical weight management and bariatric surgery in patients with type 2 diabetes: A longitudinal analysis.

Science.gov (United States)

Tang, Tien; Abbott, Sally; le Roux, Carel W; Wilson, Violet; Singhal, Rishi; Bellary, Srikanth; Tahrani, Abd A

2018-03-01

We examined the relationship between weight changes after preoperative glucagon-like peptide-1 receptor agonist (GLP-1RA) treatment and weight changes from the start of medical weight management (MWM) until 12 months after bariatric surgery in patients with type 2 diabetes in a retrospective cohort study. A total of 45 patients (64.4% women, median [interquartile range] age 49 [45-60] years) were included. The median (interquartile range) weight loss from start of MWM until 12 months post-surgery was 17.9% (13.0%-29.3%). GLP-1RA treatment during MWM resulted in 5.0% (1.9%-7.7%) weight loss. Weight loss during GLP-1RA treatment predicted weight loss from the start of MWM until 12 months post-surgery, but not postoperative weight loss after adjustment. The proportion of weight loss from start of MWM to 12 months post-surgery attributed to GLP-1RA treatment was negatively associated with that attributed to surgery, after adjustment. In conclusion, weight change after GLP-1RA treatment predicted the weight loss achieved by a combination of MWM and bariatric surgery, but not weight loss induced by surgery only. Failure to lose weight after GLP-1RA treatment should not be considered a barrier to undergoing bariatric surgery. © 2017 John Wiley & Sons Ltd.

A novel GLP-1/GIP dual agonist is more effective than liraglutide in reducing inflammation and enhancing GDNF release in the MPTP mouse model of Parkinson's disease.

Science.gov (United States)

Yuan, Ziyue; Li, Dongfang; Feng, Peng; Xue, Guofang; Ji, Chenhui; Li, Guanglai; Hölscher, Christian

2017-10-05

Type 2 diabetes mellitus (T2DM) is one of the risk factors for Parkinson's disease (PD). Insulin desensitisation has been observed in the brains of patients, which may promote neurodegeneration. Incretins are a family of growth factors that can re-sensitise insulin signalling. We have previously shown that mimetics of glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) have neuroprotective effects in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropypridine (MPTP) mouse model of PD. Recently, dual GLP-1/GIP receptor agonists have been developed. We therefore tested the novel dual agonist DA3-CH in comparison with the best GLP-1 analogue currently on the market, liraglutide (both drugs 25nmol/kg ip once-daily for 7 days) in the MPTP mouse model of PD (25mg/kg ip once-daily for 7 days). In the Rotarod and grip strength assessment, DA3-CH was superior to liraglutide in reversing the MPTP-induced motor impairment. Dopamine synthesis as indicated by levels of tyrosine hydroxylase was much reduced by MPTP in the substantia nigra and striatum, and DA3-CH reversed this while liragutide only partially reversed this. The chronic inflammation response as shown in increased levels of activated microglia and astrocytes was reduced by both drugs. Importantly, expression levels of the neuroprotective growth factor Glial Derived Neurotrophic Factor (GDNF) was much enhanced by both DA3-CH and liragutide. The results demonstrate that the combination of GLP-1 and GIP receptor activation is superior to single GLP-1 receptor activation alone. Therefore, new dual agonists may be a promising treatment for PD. The GLP-1 receptor agonist exendin-4 has already shown disease modifying effects in clinical trials in PD patients. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthetic Peptide Drugs for Targeting Skin Cancer: Malignant Melanoma and Melanotic Lesions.

Science.gov (United States)

Eberle, Alex N; Rout, Bhimsen; Qi, Mei Bigliardi; Bigliardi, Paul L

2017-01-01

Peptides play decisive roles in the skin, ranging from host defense responses to various forms of neuroendocrine regulation of cell and organelle function. Synthetic peptides conjugated to radionuclides or photosensitizers may serve to identify and treat skin tumors and their metastatic forms in other organs of the body. In the introductory part of this review, the role and interplay of the different peptides in the skin are briefly summarized, including their potential application for the management of frequently occurring skin cancers. Special emphasis is given to different targeting options for the treatment of melanoma and melanotic lesions. Radionuclide Targeting: α-Melanocyte-stimulating hormone (α-MSH) is the most prominent peptide for targeting of melanoma tumors via the G protein-coupled melanocortin-1 receptor that is (over-)expressed by melanoma cells and melanocytes. More than 100 different linear and cyclic analogs of α-MSH containing chelators for 111In, 67/68Ga, 64Cu, 90Y, 212Pb, 99mTc, 188Re were synthesized and examined with experimental animals and in a few clinical studies. Linear Ac-Nle-Asp-His-D-Phe-Arg-Trp-Gly-Lys-NH2 (NAP-amide) and Re-cyclized Cys- Cys-Glu-His-D-Phe-Arg-Trp-Cys-Arg-Pro-Val-NH2 (Re[Arg11]CCMSH) containing different chelators at the N- or C-terminus served as lead compounds for peptide drugs with further optimized characteristics. Alternatively, melanoma may be targeted with radiopeptides that bind to melanin granules occurring extracellularly in these tumors. Photosensitizer targeting: A more recent approach is the application of photosensitizers attached to the MSH molecule for targeted photodynamic therapy using LED or coherent laser light that specifically activates the photosensitizer. Experimental studies have demonstrated the feasibility of this approach as a more gentle and convenient alternative compared to radionuclides. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Disposable pencil graphite electrode modified with peptide nanotubes for Vitamin B{sub 12} analysis

Energy Technology Data Exchange (ETDEWEB)

Pala, Betül Bozdoğan [Nanotechnology and Nanomedicine Division, Institute of Science, Hacettepe University, 06800 Ankara (Turkey); Vural, Tayfun [Department of Chemistry, Faculty of Science, Hacettepe University, 06800 Beytepe, Ankara (Turkey); Kuralay, Filiz [Department of Chemistry, Faculty of Science and Arts, Ordu University, 52200 Ordu (Turkey); Çırak, Tamer [Nanotechnology and Nanomedicine Division, Institute of Science, Hacettepe University, 06800 Ankara (Turkey); Bolat, Gülçin; Abacı, Serdar [Department of Chemistry, Faculty of Science, Hacettepe University, 06800 Beytepe, Ankara (Turkey); Denkbaş, Emir Baki, E-mail: denkbas@hacettepe.edu.tr [Department of Chemistry, Faculty of Science, Hacettepe University, 06800 Beytepe, Ankara (Turkey)

2014-06-01

In this study, peptide nanostructures from diphenylalanine were synthesized in various solvents with various polarities and characterized with Scanning Electron Microscopy (SEM) and Powder X-ray Diffraction (PXRD) techniques. Formation of peptide nanofibrils, nanovesicles, nanoribbons, and nanotubes was observed in different solvent mediums. In order to investigate the effects of peptide nanotubes (PNT) on electrochemical behavior of disposable pencil graphite electrodes (PGE), electrode surfaces were modified with fabricated peptide nanotubes. Electrochemical activity of the pencil graphite electrode was increased with the deposition of PNTs on the surface. The effects of the solvent type, the peptide nanotube concentration, and the passive adsorption time of peptide nanotubes on pencil graphite electrode were studied. For further electrochemical studies, electrodes were modified for 30 min by immobilizing PNTs, which were prepared in water at 6 mg/mL concentration. Vitamin B{sub 12} analyses were performed by the Square Wave (SW) voltammetry method using modified PGEs. The obtained data showed linearity over the range of 0.2 μM and 9.50 μM Vitamin B{sub 12} concentration with high sensitivity. Results showed that PNT modified PGEs were highly simple, fast, cost effective, and feasible for the electro-analytical determination of Vitamin B{sub 12} in real samples.

Towards a peptide-based suspension array for the detection of pestivirus antibodies in swine.

Science.gov (United States)

van der Wal, Fimme J; Jelsma, Tinka; Fijten, Helmi; Achterberg, René P; Loeffen, Willie L A

2016-09-01

Classical swine fever (CSF) is a highly contagious and lethal disease in swine. Serological tests for the diagnosis of CSF need not only to detect antibodies against CSFV, but also need to differentiate these from antibodies against other pestiviruses. To investigate the possibilities of specific peptide-based serology, various synthetic peptides that represent a well-described linear epitope of the CSFV E2 protein (TAVSPTTLR) were used to test the viability of a peptide-based suspension array for the detection of antibodies against pestiviruses in swine. The results show that N-terminally biotinylated peptides can bind to avidin conjugated beads, and function in detection of the corresponding monoclonal antibody WH303. There are indications that the length of the spacer between epitope and biotin affect the efficiency of the peptide-antibody interaction. A protocol was established that enables probing for antibodies in porcine sera, where neutravidin-blocking of serum and the use of empty control beads for normalization was crucial. With a set of porcine sera with antibodies against various pestiviruses, the proof of concept of a peptide-based suspension array for specific detection of antibodies against pestiviruses in porcine sera was demonstrated. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Co-administration of α-GalCer analog and TLR4 agonist induces robust CD8+ T-cell responses to PyCS protein and WT-1 antigen and activates memory-like effector NKT cells

OpenAIRE

Coelho-dos-Reis, Jordana G.; Huang, Jing; Tsao, Tiffany; Pereira, Felipe V.; Funakoshi, Ryota; Nakajima, Hiroko; Sugiyama, Haruo; Tsuji, Moriya

2016-01-01

In the present study, the combined adjuvant effect of 7DW8-5, a potent α-GalCer-analog, and monophosphoryl lipid A (MPLA), a TLR4 agonist, on the induction of vaccine-induced CD8+ T-cell responses and protective immunity was evaluated. Mice were immunized with peptides corresponding to the CD8+ T-cell epitopes of a malaria antigen, a circumsporozoite protein of Plasmodium yoelii, and a tumor antigen, a Wilms Tumor antigen-1 (WT-1), together with 7DW8-5 and MPLA, as an adjuvant. These immuniza...

Contamination with retinoic acid receptor agonists in two rivers in the Kinki region of Japan.

Science.gov (United States)

Inoue, Daisuke; Nakama, Koki; Sawada, Kazuko; Watanabe, Taro; Takagi, Mai; Sei, Kazunari; Yang, Min; Hirotsuji, Junji; Hu, Jianying; Nishikawa, Jun-ichi; Nakanishi, Tsuyoshi; Ike, Michihiko

2010-04-01

This study was conducted to investigate the agonistic activity against human retinoic acid receptor (RAR) alpha in the Lake Biwa-Yodo River and the Ina River in the Kinki region of Japan. To accomplish this, a yeast two-hybrid assay was used to elucidate the spatial and temporal variations and potential sources of RARalpha agonist contamination in the river basins. RARalpha agonistic activity was commonly detected in the surface water samples collected along two rivers at different periods, with maximum all-trans retinoic acid (atRA) equivalents of 47.6 ng-atRA/L and 23.5 ng-atRA/L being observed in Lake Biwa-Yodo River and Ina River, respectively. The results indicated that RARalpha agonists are always present and widespread in the rivers. Comparative investigation of RARalpha and estrogen receptor alpha agonistic activities at 20 stations along each river revealed that the spatial variation pattern of RARalpha agonist contamination was entirely different from that of the estrogenic compound contamination. This suggests that the effluent from municipal wastewater treatment plants, a primary source of estrogenic compounds, seemed not to be the cause of RARalpha agonist contamination in the rivers. Fractionation using high performance liquid chromatography (HPLC) directed by the bioassay found two bioactive fractions from river water samples, suggesting the presence of at least two RARalpha agonists in the rivers. Although a trial conducted to identify RARalpha agonists in the major bioactive fraction was not completed as part of this study, comparison of retention times in HPLC analysis and quantification with liquid chromatography-mass spectrometry analysis revealed that the major causative contaminants responsible for the RARalpha agonistic activity were not RAs (natural RAR ligands) and 4-oxo-RAs, while 4-oxo-RAs were identified as the major RAR agonists in sewage in Beijing, China. These findings suggest that there are unknown RARalpha agonists with high

Targeted Delivery of LXR Agonist Using a Site-Specific Antibody-Drug Conjugate.

Science.gov (United States)

Lim, Reyna K V; Yu, Shan; Cheng, Bo; Li, Sijia; Kim, Nam-Jung; Cao, Yu; Chi, Victor; Kim, Ji Young; Chatterjee, Arnab K; Schultz, Peter G; Tremblay, Matthew S; Kazane, Stephanie A

2015-11-18

Liver X receptor (LXR) agonists have been explored as potential treatments for atherosclerosis and other diseases based on their ability to induce reverse cholesterol transport and suppress inflammation. However, this therapeutic potential has been hindered by on-target adverse effects in the liver mediated by excessive lipogenesis. Herein, we report a novel site-specific antibody-drug conjugate (ADC) that selectively delivers a LXR agonist to monocytes/macrophages while sparing hepatocytes. The unnatural amino acid para-acetylphenylalanine (pAcF) was site-specifically incorporated into anti-CD11a IgG, which binds the α-chain component of the lymphocyte function-associated antigen 1 (LFA-1) expressed on nearly all monocytes and macrophages. An aminooxy-modified LXR agonist was conjugated to anti-CD11a IgG through a stable, cathepsin B cleavable oxime linkage to afford a chemically defined ADC. The anti-CD11a IgG-LXR agonist ADC induced LXR activation specifically in human THP-1 monocyte/macrophage cells in vitro (EC50-27 nM), but had no significant effect in hepatocytes, indicating that payload delivery is CD11a-mediated. Moreover, the ADC exhibited higher-fold activation compared to a conventional synthetic LXR agonist T0901317 (Tularik) (3-fold). This novel ADC represents a fundamentally different strategy that uses tissue targeting to overcome the limitations of LXR agonists for potential use in treating atherosclerosis.

Connecting peptide (c-peptide) and the duration of diabetes mellitus ...

African Journals Online (AJOL)

Objective: C-peptide is derived from proinsulin and it is secreted in equimolar concentration with insulin. Plasma C-peptide is more stable than insulin and it provides an indirect measure of insulin secretory reserve and beta cell function. To determine relationship between C-peptide and duration of diabetes mellitus, age, ...

The Proteolytically Stable Peptidomimetic Pam-(Lys-ßNSpe)6-NH2 Selectively Inhibits Human Neutrophil Activation via Formyl Peptide Receptor 2

DEFF Research Database (Denmark)

Skovbakke, Sarah Line; Heegaard, Peter M. H.; Larsen, Camilla J.

2015-01-01

of proteolytically stable HDP mimics consisting of lipidated α-peptide/β-peptoid oligomers was investigated for their effect on neutrophil function. The most promising compound, Pam-(Lys-βNSpe)6-NH2, was shown to inhibit formyl peptide receptor 2 (FPR2) agonist-induced neutrophil granule mobilization and release...... of reactive oxygen species. The potency of Pam-(Lys-βNSpe)6-NH2 was comparable to that of PBP10, the most potent FPR2-selective inhibitor known. The immunomodulatory effects of structural analogues of Pam-(Lys-βNSpe)6-NH2 emphasized the importance of both the lipid and peptidomimetic parts. By using imaging...... flow cytometry in primary neutrophils and FPR-transfected cell lines we found that a fluorescently labelled analogue of Pam-(Lys-βNSpe)6-NH2 interacted selectively with FPR2. Furthermore the interaction between Pam-(Lys-βNSpe)6-NH2 and FPR2 was found to prevent binding of the FPR2-specific activating...

Allosteric enhancers, allosteric agonists and ago-allosteric modulators: where do they bind and how do they act?

DEFF Research Database (Denmark)

Schwartz, Thue W; Holst, Birgitte

2007-01-01

Many small-molecule agonists also display allosteric properties. Such ago-allosteric modulators act as co-agonists, providing additive efficacy--instead of partial antagonism--and they can affect--and often improve--the potency of the endogenous agonist. Surprisingly, the apparent binding sites...... different binding modes. In another, dimeric, receptor scenario, the endogenous agonist binds to one protomer while the ago-allosteric modulator binds to the other, 'allosteric' protomer. It is suggested that testing for ago-allosteric properties should be an integral part of the agonist drug discovery...... process because a compound that acts with--rather than against--the endogenous agonist could be an optimal agonist drug....

The treatment of Parkinson's disease with dopamine agonists

Directory of Open Access Journals (Sweden)

Frank, Wilhelm

2008-06-01

Full Text Available Parkinson’s disease is a chronic degenerative organic disease with unknown causes. A disappearance of cells with melanin in the substantia nigra is considered as biological artefact of the disease, which causes a degenerative loss of neurons in the corpus striatum of mesencephalon. This structure produces also the transmitter substance dopamine. Due to this disappearance of cells dopamine is not produced in a sufficient quantity which is needed for movement of the body. The questions of this report are concerned the efficiency and safety of a treatment with dopamine agonists. Furthermore the cost-effectiveness is investigated as well as ethic questions. The goal is to give recommendation for the use of dopamine agonists to the German health system. A systematic literature search was done. The identified studies have different methodological quality and investigate different hypothesis and different outcome criteria. Therefore a qualitative method of information synthesis was chosen. Since the introduction of L-Dopa in the 1960´s it is considered as the most effective substance to reduce all the cardinal symptoms of Parkinson disease. This substance was improved in the course of time. Firstly some additional substances were given (decarbonxylase inhibitors, catechol-o-transferase inhibitors (COMT-inhibitors, monoaminoxydase-inhibitors (MAO-inhibitors and NMDA-antagonists (N-Methyl-d-aspartat-antagonists. In the practical therapy of Parkinson dopamine agonists play an important role, because they directly use the dopamine receptors. The monotherapy of Parkinson disease is basically possible and is used in early stages of the disease. Clinical practise has shown, that an add on therapy with dopamine agonists can led to a reduction of the dose of L-dopa and a reduction of following dyskinesia. The studies for effectiveness include studies for the initial therapy, monotherapy and add-on-therapy. Basically there is a good effectiveness of dopamine

Fast and versatile microwave-assisted intramolecular Heck reaction in peptide macrocyclization using microwave energy.

Science.gov (United States)

Byk, Gerardo; Cohen-Ohana, Mirit; Raichman, Daniel

2006-01-01

We have revisited the intramolecular Heck reaction and investigated the microwave-assisted macrocyclization on preformed peptides using a model series of ring-varying peptides acryloyl-Gly-[Gly](n)-Phe(4-I)NHR; n = 0-4. The method was applied to both solution and solid supported cyclizations. We demonstrate that the intramolecular Heck reaction can be performed in peptides both in solution and solid support using a modified domestic microwave within 1 to 30 minutes in DMF under reflux with moderate yields ranging from 15 to 25% for a scale between 2-45 mg of linear precursors. The approach was applied to the synthesis of a constrained biologically relevant peptidomimetic bearing an Arg-Gly-Asp (RGD) sequence. These results make the microwave-assisted Heck reaction an attractive renovated approach for peptidomimetics. Copyright 2006 Wiley Periodicals, Inc.

Peptide-Carrier Conjugation

DEFF Research Database (Denmark)

Hansen, Paul Robert

2015-01-01

To produce antibodies against synthetic peptides it is necessary to couple them to a protein carrier. This chapter provides a nonspecialist overview of peptide-carrier conjugation. Furthermore, a protocol for coupling cysteine-containing peptides to bovine serum albumin is outlined....

Dopamine agonist activity of EMD 23,448

International Nuclear Information System (INIS)

Martin, G.E.; Pettibone, D.J.

1985-01-01

EMD 23,448 was examined in tests of dopaminergic function and was found to be an atypical dopamine (DA) agonist. EMD 23,448 was a weak or inactive DA agonist when examined in tests of normal postsynaptic DA receptor function: production of stereotypy in the rat (ED 50 greater than sign 5.0 mg/kg.i.p.); production of emesis in beagles (minimum effective dose = 81μg/kg i.v.); and, enhanced locomotor activity of the mouse (no excitation in doses 3 H]-apomorphine binding to rat striatal membranes (Ki, 205 nM). On the other hand, this indolyl-3-butylamine did activate supersensitive postsynaptic DA receptors. Specifically, it elicited contralateral turning in rats with a unilateral 6-hydroxydopamine lesion of the substantia nigra (ED 50 value = 0.9 mg/kg) and did elicit stereotypy in rats given chronic daily haloperidol treatments. EMD 23,448 also exerted pharmacological effects in tests designed to measure activation of dopamine autoreceptors. It inhibited the γ-butyrolactone-induced increase in striatal dopa levels (ED 50 = 1 mg/kg i.p.) and produced a dose-related fall in the locomotor activity of the mouse. The results are discussed and contrasted with data derived for apomorphine and the putatively selective autoreceptor agonist (+-)-3-PPP. (Author)

Highly selective enrichment of phosphorylated peptides from peptide mixtures using titanium dioxide microcolumns

DEFF Research Database (Denmark)

Larsen, Martin Røssel; Thingholm, Tine E; Jensen, Ole N

2005-01-01

based on TiO2microcolumns and peptide loading in 2,5-dihydroxybenzoic acid (DHB). The effect of DHB was a very efficient reduction in the binding of nonphosphorylated peptides to TiO2 while retaining its high binding affinity for phosphorylated peptides. Thus, inclusion of DHB dramatically increased...... the selectivity of the enrichment of phosphorylated peptides by TiO2. We demonstrated that this new procedure was more selective for binding phosphorylated peptides than IMAC using MALDI mass spectrometry. In addition, we showed that LC-ESI-MSMS was biased toward monophosphorylated peptides, whereas MALDI MS...... was not. Other substituted aromatic carboxylic acids were also capable of specifically reducing binding of nonphosphorylated peptides, whereas phosphoric acid reduced binding of both phosphorylated and nonphosphorylated peptides. A putative mechanism for this intriguing effect is presented....

ArrayPitope: Automated Analysis of Amino Acid Substitutions for Peptide Microarray-Based Antibody Epitope Mapping

DEFF Research Database (Denmark)

Hansen, Christian Skjødt; Østerbye, Thomas; Marcatili, Paolo

2017-01-01

-reactivity. B cell epitopes are typically classified as either linear epitopes, i.e. short consecutive segments from the protein sequence or conformational epitopes adapted through native protein folding. Recent advances in high-density peptide microarrays enable high-throughput, high-resolution identification...

A microbially derived tyrosine-sulfated peptide mimics a plant peptide hormone.

Science.gov (United States)

Pruitt, Rory N; Joe, Anna; Zhang, Weiguo; Feng, Wei; Stewart, Valley; Schwessinger, Benjamin; Dinneny, José R; Ronald, Pamela C

2017-07-01

The biotrophic pathogen Xanthomonas oryzae pv. oryzae (Xoo) produces a sulfated peptide named RaxX, which shares similarity to peptides in the PSY (plant peptide containing sulfated tyrosine) family. We hypothesize that RaxX mimics the growth-stimulating activity of PSY peptides. Root length was measured in Arabidopsis and rice treated with synthetic RaxX peptides. We also used comparative genomic analyses and reactive oxygen species burst assays to evaluate the activity of RaxX and PSY peptides. Here we found that a synthetic sulfated RaxX derivative comprising 13 residues (RaxX13-sY), highly conserved between RaxX and PSY, induces root growth in Arabidopsis and rice in a manner similar to that triggered by PSY. We identified residues that are required for activation of immunity mediated by the rice XA21 receptor but that are not essential for root growth induced by PSY. Finally, we showed that a Xanthomonas strain lacking raxX is impaired in virulence. These findings suggest that RaxX serves as a molecular mimic of PSY peptides to facilitate Xoo infection and that XA21 has evolved the ability to recognize and respond specifically to the microbial form of the peptide. © 2017 UT-Battelle LLC. New Phytologist © 2017 New Phytologist Trust.

Development and validation of an UHPLC-MS/MS method for β2-agonists quantification in human urine and application to clinical samples.

Science.gov (United States)

Bozzolino, Cristina; Leporati, Marta; Gani, Federica; Ferrero, Cinzia; Vincenti, Marco

2018-02-20

A fast analytical method for the simultaneous detection of 24 β 2 -agonists in human urine was developed and validated. The method covers the therapeutic drugs most commonly administered, but also potentially abused β 2 -agonists. The procedure is based on enzymatic deconjugation with β-glucuronidase followed by SPE clean up using mixed-phase cartridges with both ion-exchange and lipophilic properties. Instrumental analysis conducted by UHPLC-MS/MS allowed high peak resolution and rapid chromatographic separation, with reduced time and costs. The method was fully validated according ISO 17025:2005 principles. The following parameters were determined for each analyte: specificity, selectivity, linearity, limit of detection, limit of quantification, precision, accuracy, matrix effect, recovery and carry-over. The method was tested on real samples obtained from patients subjected to clinical treatment under chronic or acute therapy with either formoterol, indacaterol, salbutamol, or salmeterol. The drugs were administered using pressurized metered dose inhalers. All β 2 -agonists administered to the patients were detected in the real samples. The method proved adequate to accurately measure the concentration of these analytes in the real samples. The observed analytical data are discussed with reference to the administered dose and the duration of the therapy. Copyright © 2017 Elsevier B.V. All rights reserved.

Tumor penetrating peptides

Directory of Open Access Journals (Sweden)

Tambet eTeesalu

2013-08-01

Full Text Available Tumor-homing peptides can be used to deliver drugs into tumors. Phage library screening in live mice has recently identified homing peptides that specifically recognize the endothelium of tumor vessels, extravasate, and penetrate deep into the extravascular tumor tissue. The prototypic peptide of this class, iRGD (CRGDKGPDC, contains the integrin-binding RGD motif. RGD mediates tumor homing through binding to αv integrins, which are selectively expressed on various cells in tumors, including tumor endothelial cells. The tumor-penetrating properties of iRGD are mediated by a second sequence motif, R/KXXR/K. This C-end Rule (or CendR motif is active only when the second basic residue is exposed at the C-terminus of the peptide. Proteolytic processing of iRGD in tumors activates the cryptic CendR motif, which then binds to neuropilin-1 activating an endocytic bulk transport pathway through tumor tissue. Phage screening has also yielded tumor-penetrating peptides that function like iRGD in activating the CendR pathway, but bind to a different primary receptor. Moreover, novel tumor-homing peptides can be constructed from tumor-homing motifs, CendR elements and protease cleavage sites. Pathologies other than tumors can be targeted with tissue-penetrating peptides, and the primary receptor can also be a vascular zip code of a normal tissue. The CendR technology provides a solution to a major problem in tumor therapy, poor penetration of drugs into tumors. The tumor-penetrating peptides are capable of taking a payload deep into tumor tissue in mice, and they also penetrate into human tumors ex vivo. Targeting with these peptides specifically increases the accumulation in tumors of a variety of drugs and contrast agents, such as doxorubicin, antibodies and nanoparticle-based compounds. Remarkably the drug to be targeted does not have to be coupled to the peptide; the bulk transport system activated by the peptide sweeps along any compound that is

Influence of Dimerization of Lipopeptide Laur-Orn-Orn-Cys-NH2 and an N-terminal Peptide of Human Lactoferricin on Biological Activity.

Science.gov (United States)

Kamysz, Elżbieta; Sikorska, Emilia; Dawgul, Małgorzata; Tyszkowski, Rafał; Kamysz, Wojciech

Lactoferrin (LF) is a naturally occurring antimicrobial peptide that is cleaved by pepsin to lactoferricin (LFcin). LFcin has an enhanced antimicrobial activity as compared to that of LF. Recently several hetero- and homodimeric antimicrobial peptides stabilized by a single disulfide bond linking linear polypeptide chains have been discovered. We have demonstrated that the S-S bond heterodimerization of lipopeptide Laur-Orn-Orn-Cys-NH 2 (peptide III) and the synthetic N -terminal peptide of human lactoferricin (peptide I) yields a dimer (peptide V), which is almost as microbiologically active as the more active monomer and at the same time it is much less toxic. Furthermore, it has been found that the S-S bond homodimerization of both peptide I and peptide III did not affect antimicrobial and haemolytic activity of the compounds. The homo- and heterodimerization of peptides I and III resulted in either reduction or loss of antifungal activity. This work suggests that heterodimerization of antimicrobial lipopeptides via intermolecular disulfide bond might be a powerful modification deserving consideration in the design of antimicrobial peptides.

A general strategy for synthesis of cyclophane-braced peptide macrocycles via palladium-catalysed intramolecular sp3 C-H arylation

Science.gov (United States)

Zhang, Xuekai; Lu, Gang; Sun, Meng; Mahankali, Madhu; Ma, Yanfei; Zhang, Mingming; Hua, Wangde; Hu, Yuting; Wang, Qingbing; Chen, Jinghuo; He, Gang; Qi, Xiangbing; Shen, Weijun; Liu, Peng; Chen, Gong

2018-05-01

New methods capable of effecting cyclization, and forming novel three-dimensional structures while maintaining favourable physicochemical properties are needed to facilitate the development of cyclic peptide-based drugs that can engage challenging biological targets, such as protein-protein interactions. Here, we report a highly efficient and generally applicable strategy for constructing new types of peptide macrocycles using palladium-catalysed intramolecular C(sp3)-H arylation reactions. Easily accessible linear peptide precursors of simple and versatile design can be selectively cyclized at the side chains of either aromatic or modified non-aromatic amino acid units to form various cyclophane-braced peptide cycles. This strategy provides a powerful tool to address the long-standing challenge of size- and composition-dependence in peptide macrocyclization, and generates novel peptide macrocycles with uniquely buttressed backbones and distinct loop-type three-dimensional structures. Preliminary cell proliferation screening of the pilot library revealed a potent lead compound with selective cytotoxicity toward proliferative Myc-dependent cancer cell lines.

Analysis of agonist dissociation constants as assessed by functional antagonism in guinea pig left atria

International Nuclear Information System (INIS)

Molenaar, P.; Malta, E.

1986-01-01

In electrically driven guinea pig left atria, positive inotropic responses to (-)-isoprenaline and the selective beta 1-adrenoceptor agonist RO363 were obtained in the absence and in the presence of the functional antagonists adenosine, carbachol, gallopamil, nifedipine, and Ro 03-7894. Each of the functional antagonists reduced the maximum response to both agonists and produced nonparallel rightward shifts in the cumulative concentration effect curves. For both agonists, dissociation constants (KA) were calculated using the equation described by Furchgott (1966) for irreversible antagonism. For RO363, which is a partial agonist with high agonist activity, the equations outlined for functional interaction by Mackay (1981) were also employed to calculate KA values. The KA values obtained by each method were compared with the dissociation constants (KD) for the two agonists determined from their ability to displace the radioligand (-)-[ 125 I]iodocyanopindolol from beta 1-adrenoceptors in guinea pig left atrial membrane preparations. The estimates of KA varied substantially from KD values. The KD values were taken as more accurate estimates of the true values for the dissociation constants because a high degree of correlation exists between pKD and pD2 values for a number of other beta-adrenoceptor agonists that behave as partial agonists and between pKD and pKB values for a number of beta-adrenoceptor antagonists. Thus, it appears that there are serious limitations in the current theory for using functional antagonism as a means of obtaining agonist dissociation constants

Peptide Nucleic Acids

DEFF Research Database (Denmark)

2003-01-01

A novel class of compounds, known as peptide nucleic acids, bind complementary ssDNA and RNA strands more strongly than a corresponding DNA. The peptide nucleic acids generally comprise ligands such as naturally occurring DNA bases attached to a peptide backbone through a suitable linker....

Peptide Nucleic Acids

DEFF Research Database (Denmark)

1998-01-01

A novel class of compounds, known as peptide nucleic acids, bind complementary ssDNA and RNA strands more strongly than a corresponding DNA. The peptide nucleic acids generally comprise ligands such as naturally occurring DNA bases attached to a peptide backbone through a suitable linker....

PeptideAtlas

Data.gov (United States)

U.S. Department of Health & Human Services — PeptideAtlas is a multi-organism, publicly accessible compendium of peptides identified in a large set of tandem mass spectrometry proteomics experiments. Mass...

Synthetic peptide vaccines: palmitoylation of peptide antigens by a thioester bond increases immunogenicity

DEFF Research Database (Denmark)

Beekman, N.J.C.M.; Schaaper, W.M.M.; Tesser, G.I.

1997-01-01

Synthetic peptides have frequently been used to immunize animals. However, peptides less than about 20 to 30 amino acids long are poor immunogens. In general, to increase its immunogenicity, the presentation of the peptide should be improved, and molecular weight needs to be increased. Many...... or an amide bond. It was found that these S-palmitoylated peptides were much more immunogenic than N-palmitoylated peptides and at least similar to KLH-conjugated peptides with respect to appearance and magnitude of induced antibodies (canine parvovirus) or immunocastration effect (gonadotropin...

Development of Fluorinated Non-Peptidic Ghrelin Receptor Ligands for Potential Use in Molecular Imaging

Directory of Open Access Journals (Sweden)

Rareş-Petru Moldovan

2017-04-01

Full Text Available The ghrelin receptor (GhrR is a widely investigated target in several diseases. However, the current knowledge of its role and distribution in the brain is limited. Recently, the small and non-peptidic compound (S-6-(4-bromo-2-fluorophenoxy-3-((1-isopropylpiperidin-3-ylmethyl-2-methylpyrido[3,2-d]pyrimidin-4(3H-one ((S-9 has been described as a GhrR ligand with high binding affinity. Here, we describe the synthesis of fluorinated derivatives, the in vitro evaluation of their potency as partial agonists and selectivity at GhrRs, and their physicochemical properties. These results identified compounds (S-9, (R-9, and (S-16 as suitable parent molecules for 18F-labeled positron emission tomography (PET radiotracers to enable future investigation of GhrR in the brain.

Cell surface binding and uptake of arginine- and lysine-rich penetratin peptides in absence and presence of proteoglycans

KAUST Repository

Åmand, Helene L.

2012-11-01

Cell surface proteoglycans (PGs) appear to promote uptake of arginine-rich cell-penetrating peptides (CPPs), but their exact functions are unclear. To address if there is specificity in the interactions of arginines and PGs leading to improved internalization, we used flow cytometry to examine uptake in relation to cell surface binding for penetratin and two arginine/lysine substituted variants (PenArg and PenLys) in wildtype CHO-K1 and PG-deficient A745 cells. All peptides were more efficiently internalized into CHO-K1 than into A745, but their cell surface binding was independent of cell type. Thus, PGs promote internalization of cationic peptides, irrespective of the chemical nature of their positive charges. Uptake of each peptide was linearly dependent on its cell surface binding, and affinity is thus important for efficiency. However, the gradients of these linear dependencies varied significantly. Thus each peptide\\'s ability to stimulate uptake once bound to the cell surface is reliant on formation of specific uptake-promoting interactions. Heparin affinity chromatography and clustering experiments showed that penetratin and PenArg binding to sulfated sugars is stabilized by hydrophobic interactions and result in clustering, whereas PenLys only interacts through electrostatic attraction. This may have implications for the molecular mechanisms behind arginine-specific uptake stimulation as penetratin and PenArg are more efficiently internalized than PenLys upon interaction with PGs. However, PenArg is also least affected by removal of PGs. This indicates that an increased arginine content not only improve PG-dependent uptake but also that PenArg is more adaptable as it can use several portals of entry into the cell. © 2012 Elsevier B.V.

Inhibition by TRPA1 agonists of compound action potentials in the frog sciatic nerve

Energy Technology Data Exchange (ETDEWEB)

Matsushita, Akitomo; Ohtsubo, Sena; Fujita, Tsugumi; Kumamoto, Eiichi, E-mail: kumamote@cc.saga-u.ac.jp

2013-04-26

Highlights: •TRPA1 agonists inhibited compound action potentials in frog sciatic nerves. •This inhibition was not mediated by TRPA1 channels. •This efficacy was comparable to those of lidocaine and cocaine. •We found for the first time an ability of TRPA1 agonists to inhibit nerve conduction. -- Abstract: Although TRPV1 and TRPM8 agonists (vanilloid capsaicin and menthol, respectively) at high concentrations inhibit action potential conduction, it remains to be unknown whether TRPA1 agonists have a similar action. The present study examined the actions of TRPA1 agonists, cinnamaldehyde (CA) and allyl isothiocyanate (AITC), which differ in chemical structure from each other, on compound action potentials (CAPs) recorded from the frog sciatic nerve by using the air-gap method. CA and AITC concentration-dependently reduced the peak amplitude of the CAP with the IC{sub 50} values of 1.2 and 1.5 mM, respectively; these activities were resistant to a non-selective TRP antagonist ruthenium red or a selective TRPA1 antagonist HC-030031. The CA and AITC actions were distinct in property; the latter but not former action was delayed in onset and partially reversible, and CA but not AITC increased thresholds to elicit CAPs. A CAP inhibition was seen by hydroxy-α-sanshool (by 60% at 0.05 mM), which activates both TRPA1 and TRPV1 channels, a non-vanilloid TRPV1 agonist piperine (by 20% at 0.07 mM) and tetrahydrolavandulol (where the six-membered ring of menthol is opened; IC{sub 50} = 0.38 mM). It is suggested that TRPA1 agonists as well as TRPV1 and TRPM8 agonists have an ability to inhibit nerve conduction without TRP activation, although their agonists are quite different in chemical structure from each other.

Low-dose add-back therapy during postoperative GnRH agonist treatment

Directory of Open Access Journals (Sweden)

Hsiao-Wen Tsai

2016-02-01

Conclusion: Low dose add-back therapy could effectively ameliorate hypoestrogenic side effects and simultaneously maintain the therapeutic response of GnRH agonist treatment. The treatment dropout was lower compared with a regular dose. Therefore, low dose add-back therapy can be considered a treatment choice during postoperative GnRH agonist treatment.

Scaffold-based pan-agonist design for the PPARα, PPARβ and PPARγ receptors.

Directory of Open Access Journals (Sweden)

Li-Song Zhang

Full Text Available As important members of nuclear receptor superfamily, Peroxisome proliferator-activated receptors (PPAR play essential roles in regulating cellular differentiation, development, metabolism, and tumorigenesis of higher organisms. The PPAR receptors have 3 identified subtypes: PPARα, PPARβ and PPARγ, all of which have been treated as attractive targets for developing drugs to treat type 2 diabetes. Due to the undesirable side-effects, many PPAR agonists including PPARα/γ and PPARβ/γ dual agonists are stopped by US FDA in the clinical trials. An alternative strategy is to design novel pan-agonist that can simultaneously activate PPARα, PPARβ and PPARγ. Under such an idea, in the current study we adopted the core hopping algorithm and glide docking procedure to generate 7 novel compounds based on a typical PPAR pan-agonist LY465608. It was observed by the docking procedures and molecular dynamics simulations that the compounds generated by the core hopping and glide docking not only possessed the similar functions as the original LY465608 compound to activate PPARα, PPARβ and PPARγ receptors, but also had more favorable conformation for binding to the PPAR receptors. The additional absorption, distribution, metabolism and excretion (ADME predictions showed that the 7 compounds (especially Cpd#1 hold high potential to be novel lead compounds for the PPAR pan-agonist. Our findings can provide a new strategy or useful insights for designing the effective pan-agonists against the type 2 diabetes.

The good, the bad, and the ugly: agonistic behaviour in juvenile crocodilians.

Directory of Open Access Journals (Sweden)

Matthew L Brien

Full Text Available We examined agonistic behaviour in seven species of hatchling and juvenile crocodilians held in small groups (N = 4 under similar laboratory conditions. Agonistic interactions occurred in all seven species, typically involved two individuals, were short in duration (5-15 seconds, and occurred between 1600-2200 h in open water. The nature and extent of agonistic interactions, the behaviours displayed, and the level of conspecific tolerance varied among species. Discrete postures, non-contact and contact movements are described. Three of these were species-specific: push downs by C. johnstoni; inflated tail sweeping by C. novaeguineae; and, side head striking combined with tail wagging by C. porosus. The two long-snouted species (C. johnstoni and G. gangeticus avoided contact involving the head and often raised the head up out of the way during agonistic interactions. Several behaviours not associated with aggression are also described, including snout rubbing, raising the head up high while at rest, and the use of vocalizations. The two most aggressive species (C. porosus, C. novaeguineae appeared to form dominance hierarchies, whereas the less aggressive species did not. Interspecific differences in agonistic behaviour may reflect evolutionary divergence associated with morphology, ecology, general life history and responses to interspecific conflict in areas where multiple species have co-existed. Understanding species-specific traits in agonistic behaviour and social tolerance has implications for the controlled raising of different species of hatchlings for conservation, management or production purposes.

Peptide retention prediction using hydrophilic interaction liquid chromatography coupled to mass spectrometry.

Science.gov (United States)

Badgett, Majors J; Boyes, Barry; Orlando, Ron

2018-02-16

A model that predicts retention for peptides using a HALO ® penta-HILIC column and gradient elution was created. Coefficients for each amino acid were derived using linear regression analysis and these coefficients can be summed to predict the retention of peptides. This model has a high correlation between experimental and predicted retention times (0.946), which is on par with previous RP and HILIC models. External validation of the model was performed using a set of H. pylori samples on the same LC-MS system used to create the model, and the deviation from actual to predicted times was low. Apart from amino acid composition, length and location of amino acid residues on a peptide were examined and two site-specific corrections for hydrophobic residues at the N-terminus as well as hydrophobic residues one spot over from the N-terminus were created. Copyright © 2017 Elsevier B.V. All rights reserved.

Folding and membrane insertion of the pore-forming peptide gramicidin occur as a concerted process.

Science.gov (United States)

Hicks, Matthew R; Damianoglou, Angeliki; Rodger, Alison; Dafforn, Timothy R

2008-11-07

Many antibiotic peptides function by binding and inserting into membranes. Understanding this process provides an insight into the fundamentals of both membrane protein folding and antibiotic peptide function. For the first time, in this work, flow-aligned linear dichroism (LD) is used to study the folding of the antibiotic peptide gramicidin. LD provides insight into the combined processes of peptide folding and insertion and has the advantage over other similar techniques of being insensitive to off-membrane aggregation events. By combining LD data with conventional measurements of protein fluorescence and circular dichroism, the mechanism of gramicidin insertion is elucidated. The mechanism consists of five separately assignable steps that include formation of a water-insoluble gramicidin aggregate, dissociation from the aggregate, partitioning of peptide to the membrane surface, oligomerisation on the surface and concerted insertion and folding of the peptide to the double-helical form of gramicidin. Measurement of the rates of each step shows that although changes in the fluorescence signal cease 10 s after the initiation of the process, the insertion of the peptide into the membrane is actually not complete for a further 60 min. This last membrane insertion phase is only apparent by measurement of LD and circular dichroism signal changes. In summary, this study demonstrates the importance of multi-technique approaches, including LD, in studies of membrane protein folding.

Rational design and synthesis of altered peptide ligands based on human myelin oligodendrocyte glycoprotein 35-55 epitope: inhibition of chronic experimental autoimmune encephalomyelitis in mice.

Science.gov (United States)

Tselios, Theodore; Aggelidakis, Mihalis; Tapeinou, Anthi; Tseveleki, Vivian; Kanistras, Ioannis; Gatos, Dimitrios; Matsoukas, John

2014-11-04

Experimental autoimmune encephalomyelitis (EAE) is a demyelinating disease of the central nervous system and is an animal model of multiple sclerosis (MS). Although the etiology of MS remains unclear, there is evidence T-cell recognition of immunodominant epitopes of myelin proteins, such as the 35-55 epitope of myelin oligodendrocyte glycoprotein (MOG), plays a pathogenic role in the induction of chronic EAE. Cyclization of peptides is of great interest since the limited stability of linear peptides restricts their potential use as therapeutic agents. Herein, we have designed and synthesized a number of linear and cyclic peptides by mutating crucial T cell receptor (TCR) contact residues of the human MOG35-55 epitope. In particular, we have designed and synthesized cyclic altered peptide ligands (APLs) by mutating Arg41 with Ala or Arg41 and Arg46 with Ala. The peptides were synthesized in solid phase on 2-chlorotrityl chloride resin (CLTR-Cl) using the Fmoc/t-Bu methodology. The purity of final products was verified by RP-HPLC and their identification was achieved by ESI-MS. It was found that the substitutions of Arg at positions 41 and 46 with Ala results in peptide analogues that reduce the severity of MOG-induced EAE clinical symptoms in C57BL/6 mice when co-administered with mouse MOG35-55 peptide at the time of immunization.

Structure and biological activity of endogenous and synthetic agonists of GPR119

Science.gov (United States)

Tyurenkov, I. N.; Ozerov, A. A.; Kurkin, D. V.; Logvinova, E. O.; Bakulin, D. A.; Volotova, E. V.; Borodin, D. D.

2018-02-01

A G-protein-coupled receptor, GPR119, is a promising pharmacological target for a new class of hypoglycaemic drugs with an original mechanism of action, namely, increase in the glucose-dependent incretin and insulin secretion. In 2005, the first ligands were found and in the subsequent years, a large number of GPR119 agonists were synthesized in laboratories in various countries; the safest and most promising agonists have entered phase I and II clinical trials as agents for the treatment of type 2 diabetes mellitus and obesity. The review describes the major endogenous GPR119 agonists and the main trends in the design and modification of synthetic structures for increasing the hypoglycaemic activity. The data on synthetic agonists are arranged according to the type of the central core of the molecules. The bibliography includes 104 references.

Interleukin-24 as a target cytokine of environmental aryl hydrocarbon receptor agonist exposure in the lung

Energy Technology Data Exchange (ETDEWEB)

Luo, Yueh-Hsia; Kuo, Yu-Chun; Tsai, Ming-Hsien; Ho, Chia-Chi; Tsai, Hui-Ti; Hsu, Chin-Yu; Chen, Yu-Cheng; Lin, Pinpin, E-mail: pplin@nhri.org.tw

2017-06-01

Exposure to environmental aryl hydrocarbon receptor (AhR) agonists, such as halogenated aromatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs), has great impacts on the development of various lung diseases. As emerging molecular targets for AhR agonists, cytokines may contribute to the inflammatory or immunotoxic effects of environmental AhR agonists. However, general cytokine expression may not specifically indicate environmental AhR agonist exposure. By comparing cytokine and chemokine expression profiles in human lung adenocarcinoma cell line CL5 treated with AhR agonists and the non-AhR agonist polychlorinated biphenyl (PCB) 39, we identified a target cytokine of environmental AhR agonist exposure of in the lungs. Thirteen cytokine and chemokine genes were altered in the AhR agonists-treated cells, but none were altered in the PCB39-treated cells. Interleukin (IL)-24 was the most highly induced gene among AhR-modulated cytokines. Cotreatment with AhR antagonist completely prevented IL-24 induction by AhR agonists in the CL5 cells. Knockdown AhR expression with short-hairpin RNA (shRNA) significantly reduced benzo[a]pyrene (BaP)-induced IL-24 mRNA levels. We further confirmed that gene transcription, but not mRNA stability, was involved in IL-24 upregulation by BaP. Particulate matter (PM) in the ambient air contains some PAHs and is reported to activate AhR. Oropharyngeal aspiration of PM significantly increased IL-24 levels in lung epithelia and in bronchoalveolar lavage fluid of mice 4 weeks after treatment. Thus, our data suggests that IL-24 is a pulmonary exposure target cytokine of environmental AhR agonists. - Graphical abstract: (A) Cytokine and chemokine gene expressions were examined in CL5 cells treated with AhR and non-AhR agonists. Thirteen cytokines and chemokines genes were altered in the AhR agonist-treated cells, but not in the non-AhR agonist-treated cells. IL-24 was the most highly induced gene among the AhR-modulated cytokines. (B

Tuning electronic transport via hepta-alanine peptides junction by tryptophan doping.

Science.gov (United States)

Guo, Cunlan; Yu, Xi; Refaely-Abramson, Sivan; Sepunaru, Lior; Bendikov, Tatyana; Pecht, Israel; Kronik, Leeor; Vilan, Ayelet; Sheves, Mordechai; Cahen, David

2016-09-27

Charge migration for electron transfer via the polypeptide matrix of proteins is a key process in biological energy conversion and signaling systems. It is sensitive to the sequence of amino acids composing the protein and, therefore, offers a tool for chemical control of charge transport across biomaterial-based devices. We designed a series of linear oligoalanine peptides with a single tryptophan substitution that acts as a "dopant," introducing an energy level closer to the electrodes' Fermi level than that of the alanine homopeptide. We investigated the solid-state electron transport (ETp) across a self-assembled monolayer of these peptides between gold contacts. The single tryptophan "doping" markedly increased the conductance of the peptide chain, especially when its location in the sequence is close to the electrodes. Combining inelastic tunneling spectroscopy, UV photoelectron spectroscopy, electronic structure calculations by advanced density-functional theory, and dc current-voltage analysis, the role of tryptophan in ETp is rationalized by charge tunneling across a heterogeneous energy barrier, via electronic states of alanine and tryptophan, and by relatively efficient direct coupling of tryptophan to a Au electrode. These results reveal a controlled way of modulating the electrical properties of molecular junctions by tailor-made "building block" peptides.

Cross-recognition of a pit viper (Crotalinae) polyspecific antivenom explored through high-density peptide microarray epitope mapping

DEFF Research Database (Denmark)

Engmark, Mikael; Lomonte, Bruno; Gutiérrez, José María

2017-01-01

Snakebite antivenom is a 120 years old invention based on polyclonal mixtures of antibodies purified from the blood of hyper-immunized animals. Knowledge on antibody recognition sites (epitopes) on snake venom proteins is limited, but may be used to provide molecular level explanations...... for antivenom cross-reactivity. In turn, this may help guide antivenom development by elucidating immunological biases in existing antivenoms. In this study, we have identified and characterized linear elements of B-cell epitopes from 870 pit viper venom protein sequences by employing a high......-throughput methodology based on custom designed high-density peptide microarrays. By combining data on antibody-peptide interactions with multiple sequence alignments of homologous toxin sequences and protein modelling, we have determined linear elements of antibody binding sites for snake venom metalloproteases (SVMPs...

Diversity-oriented peptide stapling

DEFF Research Database (Denmark)

Tran, Thu Phuong; Larsen, Christian Ørnbøl; Røndbjerg, Tobias

2017-01-01

as a powerful method for peptide stapling. However, to date CuAAC stapling has not provided a simple method for obtaining peptides that are easily diversified further. In the present study, we report a new diversity-oriented peptide stapling (DOPS) methodology based on CuAAC chemistry. Stapling of peptides...

Do Agonistic Motives Matter More Than Anger? Three Studies of Cardiovascular Risk in Adolescents

Science.gov (United States)

Ewart, Craig K.; Elder, Gavin J.; Smyth, Joshua M.; Sliwinski, Martin J.; Jorgensen, Randall S.

2011-01-01

Objective Three motivational profiles have been associated with recurring psychological stress in low-income youth and young adults: Striving to control others (agonistic striving), striving to control the self (transcendence striving), and not asserting control (dissipated striving); Agonistic Striving has been associated with elevated ambulatory blood pressure during daily activities. Three studies tested the hypotheses that: (1) Agonistic Striving is associated with poor anger regulation, and (2) Agonistic Striving and poor anger regulation interactively elevate blood pressure. Design Motivational profiles, anger regulation, and ambulatory blood pressure were assessed in a multiethnic sample of 264 urban youth. Main outcome measures (1) Anger regulation/recovery during laboratory challenge; (2) anger / blood pressure during daily activities (48 hours). Results and conclusion Replication of the profiles in distant cities showed they occur with similar frequency across differences of region, race, and gender. Analyses controlling for body size, race, and gender revealed that individuals with the Agonistic Striving profile had higher ambulatory pressure, especially during social encounters. They became more openly angry and aggressive when challenged, but did not exhibit difficulty regulating anger in the laboratory, nor did they feel more angry during monitoring. However, individuals with the Agonistic Striving profile who did display poor anger regulation in the lab had the highest blood pressure; deficient self-regulatory capability amplified the positive association between Agonistic Striving and cardiovascular risk in both genders and all ethnic groups. Although anger is thought to increase cardiovascular risk, present findings suggest that anger and elevated blood pressure are co-effects of agonistic struggles to control others. PMID:21534673

Effect of a Fusion Peptide by Covalent Conjugation of a Mitochondrial Cell-Penetrating Peptide and a Glutathione Analog Peptide

Directory of Open Access Journals (Sweden)

Carmine Pasquale Cerrato

2017-06-01

Full Text Available Previously, we designed and synthesized a library of mitochondrial antioxidative cell-penetrating peptides (mtCPPs superior to the parent peptide, SS31, to protect mitochondria from oxidative damage. A library of antioxidative glutathione analogs called glutathione peptides (UPFs, exceptional in hydroxyl radical elimination compared with glutathione, were also designed and synthesized. Here, a follow-up study is described, investigating the effects of the most promising members from both libraries on reactive oxidative species scavenging ability. None of the peptides influenced cell viability at the concentrations used. Fluorescence microscopy studies showed that the fluorescein-mtCPP1-UPF25 (mtgCPP internalized into cells, and spectrofluorometric analysis determined the presence and extent of peptide into different cell compartments. mtgCPP has superior antioxidative activity compared with mtCPP1 and UPF25 against H2O2 insult, preventing ROS formation by 2- and 3-fold, respectively. Moreover, we neither observed effects on mitochondrial membrane potential nor production of ATP. These data indicate that mtgCPP is targeting mitochondria, protecting them from oxidative damage, while also being present in the cytosol. Our hypothesis is based on a synergistic effect resulting from the fused peptide. The mitochondrial peptide segment is targeting mitochondria, whereas the glutathione analog peptide segment is active in the cytosol, resulting in increased scavenging ability.

Peptide-membrane interactions of arginine-tryptophan peptides probed using quartz crystal microbalance with dissipation monitoring.

KAUST Repository

Rydberg, Hanna A

2014-04-18

Membrane-active peptides include peptides that can cross cellular membranes and deliver macromolecular cargo as well as peptides that inhibit bacterial growth. Some of these peptides can act as both transporters and antibacterial agents. It is desirable to combine the knowledge from these two different fields of membrane-active peptides into design of new peptides with tailored actions, as transporters of cargo or as antibacterial substances, targeting specific membranes. We have previously shown that the position of the amino acid tryptophan in the peptide sequence of three arginine-tryptophan peptides affects their uptake and intracellular localization in live mammalian cells, as well as their ability to inhibit bacterial growth. Here, we use quartz crystal microbalance with dissipation monitoring to assess the induced changes caused by binding of the three peptides to supported model membranes composed of POPC, POPC/POPG, POPC/POPG/cholesterol or POPC/lactosyl PE. Our results indicate that the tryptophan position in the peptide sequence affects the way these peptides interact with the different model membranes and that the presence of cholesterol in particular seems to affect the membrane interaction of the peptide with an even distribution of tryptophans in the peptide sequence. These results give mechanistic insight into the function of these peptides and may aid in the design of membrane-active peptides with specified cellular targets and actions.

Peptide-membrane interactions of arginine-tryptophan peptides probed using quartz crystal microbalance with dissipation monitoring.

KAUST Repository

Rydberg, Hanna A; Kunze, Angelika; Carlsson, Nils; Altgä rde, Noomi; Svedhem, Sofia; Nordé n, Bengt

2014-01-01

Membrane-active peptides include peptides that can cross cellular membranes and deliver macromolecular cargo as well as peptides that inhibit bacterial growth. Some of these peptides can act as both transporters and antibacterial agents. It is desirable to combine the knowledge from these two different fields of membrane-active peptides into design of new peptides with tailored actions, as transporters of cargo or as antibacterial substances, targeting specific membranes. We have previously shown that the position of the amino acid tryptophan in the peptide sequence of three arginine-tryptophan peptides affects their uptake and intracellular localization in live mammalian cells, as well as their ability to inhibit bacterial growth. Here, we use quartz crystal microbalance with dissipation monitoring to assess the induced changes caused by binding of the three peptides to supported model membranes composed of POPC, POPC/POPG, POPC/POPG/cholesterol or POPC/lactosyl PE. Our results indicate that the tryptophan position in the peptide sequence affects the way these peptides interact with the different model membranes and that the presence of cholesterol in particular seems to affect the membrane interaction of the peptide with an even distribution of tryptophans in the peptide sequence. These results give mechanistic insight into the function of these peptides and may aid in the design of membrane-active peptides with specified cellular targets and actions.

Automated solid-phase peptide synthesis to obtain therapeutic peptides

Directory of Open Access Journals (Sweden)

Veronika Mäde

2014-05-01

Full Text Available The great versatility and the inherent high affinities of peptides for their respective targets have led to tremendous progress for therapeutic applications in the last years. In order to increase the drugability of these frequently unstable and rapidly cleared molecules, chemical modifications are of great interest. Automated solid-phase peptide synthesis (SPPS offers a suitable technology to produce chemically engineered peptides. This review concentrates on the application of SPPS by Fmoc/t-Bu protecting-group strategy, which is most commonly used. Critical issues and suggestions for the synthesis are covered. The development of automated methods from conventional to essentially improved microwave-assisted instruments is discussed. In order to improve pharmacokinetic properties of peptides, lipidation and PEGylation are described as covalent conjugation methods, which can be applied by a combination of automated and manual synthesis approaches. The synthesis and application of SPPS is described for neuropeptide Y receptor analogs as an example for bioactive hormones. The applied strategies represent innovative and potent methods for the development of novel peptide drug candidates that can be manufactured with optimized automated synthesis technologies.

Structural characterization by NMR of a double phosphorylated chimeric peptide vaccine for treatment of Alzheimer's disease.

Science.gov (United States)

Ramírez-Gualito, Karla; Richter, Monique; Matzapetakis, Manolis; Singer, David; Berger, Stefan

2013-04-26

Rational design of peptide vaccines becomes important for the treatment of some diseases such as Alzheimer's disease (AD) and related disorders. In this study, as part of a larger effort to explore correlations of structure and activity, we attempt to characterize the doubly phosphorylated chimeric peptide vaccine targeting a hyperphosphorylated epitope of the Tau protein. The 28-mer linear chimeric peptide consists of the double phosphorylated B cell epitope Tau₂₂₉₋₂₃₇[pThr231/pSer235] and the immunomodulatory T cell epitope Ag85B₂₄₁₋₂₅₅ originating from the well-known antigen Ag85B of the Mycobacterium tuberculosis, linked by a four amino acid sequence -GPSL-. NMR chemical shift analysis of our construct demonstrated that the synthesized peptide is essentially unfolded with a tendency to form a β-turn due to the linker. In conclusion, the -GPSL- unit presumably connects the two parts of the vaccine without transferring any structural information from one part to the other. Therefore, the double phosphorylated epitope of the Tau peptide is flexible and accessible.

Production of peptide antisera specific for mouse and rat proinsulin C-peptide 2

DEFF Research Database (Denmark)

Blume, N; Madsen, O D; Kofod, Hans

1990-01-01

for antibody binding to the immunizing antigen. Antisera to C-peptide 2, stained islet beta-cells on mouse and rat, but not monkey pancreas sections in immunocytochemical analysis. Preabsorption to the synthetic C-peptide 2, but not the synthetic mouse and rat C-peptide 1 abolished staining. In conclusion we......Mice and rats have two functional non-allelic insulin genes. By using a synthetic peptide representing a common sequence in mouse and rat C-peptide 2 as antigen, we have produced rabbit antisera specific for an epitope which is not present in mouse or rat C-peptide 1. Long-term immunization did...... not seem to increase the end point titre as tested in direct ELISA. The specificity of the antiserum was determined by competitive ELISA and histochemistry on pancreas sections. Only the synthetic C-peptide 2, but not the homologous synthetic C-peptide 1 from mouse and rat competed efficiently in ELISA...

Therapeutic peptides for cancer therapy. Part I - peptide inhibitors of signal transduction cascades.

Science.gov (United States)

Bidwell, Gene L; Raucher, Drazen

2009-10-01

Therapeutic peptides have great potential as anticancer agents owing to their ease of rational design and target specificity. However, their utility in vivo is limited by low stability and poor tumor penetration. The authors review the development of peptide inhibitors with potential for cancer therapy. Peptides that inhibit signal transduction cascades are discussed. The authors searched Medline for articles concerning the development of therapeutic peptides and their delivery. Given our current knowledge of protein sequences, structures and interaction interfaces, therapeutic peptides that inhibit interactions of interest are easily designed. These peptides are advantageous because they are highly specific for the interaction of interest, and they are much more easily developed than small molecule inhibitors of the same interactions. The main hurdle to application of peptides for cancer therapy is their poor pharmacokinetic and biodistribution parameters. Therefore, successful development of peptide delivery vectors could potentially make possible the use of this new and very promising class of anticancer agents.

Application of biomimetic HPLC to estimate lipophilicity, protein and phospholipid binding of potential peptide therapeutics

Directory of Open Access Journals (Sweden)

Klara Livia Valko

2018-06-01

Full Text Available Peptide therapeutics are new modalities offering several challenges to drug discovery. They are generally less stable and permeable in vivo. The characterization of their lipophilicity cannot be carried out using the traditional in silico or wet octanol/water partition coefficients. The prediction of their in vivo distribution and permeability is also challenging. In this paper, it is demonstrated that the biomimetic properties such as lipophilicity, protein and phospholipid binding can be easily assessed by HPLC using chemically bonded protein and immobilized artificial membrane (IAM stationary phases. The obtained properties for a set of potential therapeutic peptides with 3 to 33 amino acids have been analysed and it was found that similar characteristics of the properties could be observed as for small molecule drugs. The albumin binding showed correlation with their measured lipophilicity on the C-18 stationary phase with acidic peptides showing stronger than expected albumin binding. The (IAM chromatography revealed peptide membrane affinity, which was stronger for positively charged peptides (containing arginine and showed correlation to the alpha-1-acid glycoprotein (AGP binding, which was also stronger for positively charged compounds. The in vivo volume of distribution and drug efficiency of the peptides have been estimated using the models developed for small molecules. One of the candidate linear peptides has been assessed in various cellular and in vivo assays and the results have confirmed the estimated cell partition and brain to plasma ratio. It can be demonstrated, that up to 21 amino acids, the peaks of the peptides obtained on the protein phase were symmetrical and narrow. The interaction of larger peptides with the protein stationary phases resulted in wide peaks showing multiple equilibrium processes with slow kinetics during chromatography. The larger peptides showed narrow and symmetrical peaks on the IAM column enabling

Purification and use of E. coli peptide deformylase for peptide deprotection in chemoenzymatic peptide synthesis

NARCIS (Netherlands)

Di Toma, Claudia; Sonke, Theo; Quaedflieg, Peter J.; Janssen, Dick B.

Peptide deformylases (PDFs) catalyze the removal of the formyl group from the N-terminal methionine residue in nascent polypeptide chains in prokaryotes. Its deformylation activity makes PDF an attractive candidate for the biocatalytic deprotection of formylated peptides that are used in

Antioxidant activity of yoghurt peptides: Part 2 – Characterisationof peptide fractions

DEFF Research Database (Denmark)

Farvin, Sabeena; Baron, Caroline; Nielsen, Nina Skall

2010-01-01

the peptides identified contained at least one proline residue. Some of the identified peptides included the hydrophobic amino acid residues Val or Leu at the N-terminus and Pro, His or Tyr in the amino acid sequence, which is characteristic of antioxidant peptides. In addition, the yoghurt contained...