Thursday, January 19, 2012

synthetic peptide| What issynthetic peptide |Papers on synthetic peptide|Research on synthetic peptide| Publications on synthetic peptide


1.
PLoS One. 2012;7(1):e30052. Epub 2012 Jan 11.

Novel protocol for the chemical synthesis of crustacean hyperglycemic hormone analogues - an efficient experimental tool for studying their functions.

Source

Department of Life Sciences, University of Trieste, Trieste, Italy.

Abstract

The crustacean Hyperglycemic Hormone (cHH) is present in many decapods in different isoforms, whose specific biological functions are still poorly understood. Here we report on the first chemical synthesis of three distinct isoforms of the cHH of Astacus leptodactylus carried out by solid phase peptide synthesis coupled to native chemical ligation. The synthetic 72 amino acid long peptide amides, containing L- or D-Phe(3) and (Glp(1), D-Phe(3)) were tested for their biological activity by means of homologous in vivo bioassays. The hyperglycemic activity of the D-isoforms was significantly higher than that of the L-isoform, while the presence of the N-terminal Glp residue had no influence on thepeptide activity. The results show that the presence of D-Phe(3) modifies the cHH functionality, contributing to the diversification of the hormone pool.

PMID:
22253873
[PubMed - in process]
2.
J Pept Sci. 2012 Jan 17. doi: 10.1002/psc.1436. [Epub ahead of print]

Determination of counter-ions in synthetic peptides by ion chromatography, capillary isotachophoresis and capillary electrophoresis.

Source

Department of Inorganic Chemistry, Faculty of Pharmacy, Medical University of Gdansk, al. Hallera 107, 80-416, Gdansk, Poland. wojmrozik@gumed.edu.pl.

Abstract

The utility of three various analytical techniques [ion chromatography (IC), capillary electrophoresis (CE) and isotachophoresis (ITP)] was tested in the determination of counter-ions in synthetic peptides. The analyzed ions were acetates, trifluoroacetates and chlorides. IC provided the best results; CE, except limit of detection and limit of quantification, exhibited the comparable results. ITP was classified as the less useful because of the problem with the determination of the chloride ions. Nevertheless, all the three techniques were able to analyze trifluoroacetates and acetates ions with satisfactory results. Except analytical methods, three procedures using hydrochloric acid (HCl) (at two different concentrations) and acetic acid as sample solvents processed by lyophilization were tested. It has been found that the lyophilization not only by HCl but also by acetic acid is a simple and cheap procedure for removal of toxic trifluoroacetic counter-ions from peptides on satisfactory levels. Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.

Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.

PMID:
22252914
[PubMed - as supplied by publisher]
3.
J Chromatogr A. 2011 Dec 29. [Epub ahead of print]

Novel peptide ligand with high binding capacity for antibody purification.

Source

Novo Nordisk A/S, Hagedornsvej 1, DK-2820 Gentofte, Denmark; Department of Biochemistry and Molecular Biology, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark.

Abstract

Small synthetic ligands for protein purification have become increasingly interesting with the growing need for cheap chromatographic materials for protein purification and especially for the purification of monoclonal antibodies (mAbs). Today, Protein A-based chromatographic resins are the most commonly used capture step in mAb down stream processing; however, the use of Protein A chromatography is less attractive due to toxic ligand leakage as well as high cost. Whether used as an alternative to the Protein A chromatographic media or as a subsequent polishing step, smallsynthetic peptide ligands have an advantage over biological ligands; they are cheaper to produce, ligand leakage by enzymatic degradation is either eliminated or significantly reduced, and they can in general better withstand cleaning in place (CIP) conditions such as 0.1M NaOH. Here, we present a novel synthetic peptide ligand for purification of human IgG. Immobilized on WorkBeads, an agarose-based base matrix from Bio-Works, the ligand has a dynamic binding capacity of up to 48mg/mL and purifies IgG from harvest cell culture fluid with purities and recovery of >93%. The binding affinity is ∼10(5)M(-1) and the interaction is favorable and entropy-driven with an enthalpy penalty. Our results show that the binding of the Fc fragment of IgG is mediated by hydrophobic interactions and that elution at low pH is most likely due to electrostatic repulsion. Furthermore, we have separated aggregated IgG from non-aggregated IgG, indicating that the ligand could be used both as a primary purification step of IgG as well as a subsequent polishing step.

Copyright © 2012 Elsevier B.V. All rights reserved.

PMID:
22251884
[PubMed - as supplied by publisher]
4.
J Pept Sci. 2012 Jan 16. doi: 10.1002/psc.1434. [Epub ahead of print]

Synthesis of anticancer heptapeptides containing a unique lipophilic β(2,2) -amino acid building block.

Source

Department of Pharmacy, Faculty of Health Sciences, University of Tromsø, NO-9037, Tromsø, Norway.

Abstract

We report a series of synthetic anticancer heptapeptides (H-KKWβ(2,2) WKK-NH(2) ) containing eight different central lipophilic β(2,2) -amino acid building blocks, which have demonstrated high efficiency when used as scaffolds in small cationic antimicrobial peptides and peptidomimetics. The most potent peptides in the present study had IC(50) values of 9-23 µm against human Burkitt's lymphoma and murine B-cell lymphoma and were all nonhaemolytic (EC(50)  > 200 µm). The most promising peptide 10e also demonstrated low toxicity against human embryonic lung fibroblast cells and peripheral blood mononuclear cells and exceptional proteolytic stability. Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.

Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.

PMID:
22249949
[PubMed - as supplied by publisher]
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5.
J Pept Sci. 2012 Jan 16. doi: 10.1002/psc.1433. [Epub ahead of print]

Stereoselective synthesis of fully protected (2S,4S,6S)-2-amino-6-hydroxy-4-methyl-8-oxodecanoic acid (AHMOD).

Source

Department of Medicinal Chemistry, School of Pharmacy, Fudan University, Shanghai, 201203, China.

Abstract

The stereocontrolled synthesis of fully protected (2S,4S,6S)-2-amino-6-hydroxy-4-methyl-8-oxodecanoic acid was accomplished using a glutamate derivative as starting material. The key steps of this stereochemical synthetic pathway involved an Evans asymmetric alkylation, a Sharpless asymmetric epoxidation, and a Grignard reaction. Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.

Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.

PMID:
22249935
[PubMed - as supplied by publisher]
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6.
J Pept Sci. 2012 Jan 16. doi: 10.1002/psc.1430. [Epub ahead of print]

The use of 2,2'-dithiobis(5-nitropyridine) (DTNP) for deprotection and diselenide formation in protected selenocysteine-containing peptides.

Source

Department of Chemistry, Saint Michael's College, One Winooski Park, Colchester, VT, 05439, USA.

Abstract

In contrast to the large number of sidechain protecting groups available for cysteine derivatives in solid phase peptidesynthesis, there is a striking paucity of analogous selenocysteine Se-protecting groups in the literature. However, the growing interest in selenocysteine-containing peptides and proteins requires a corresponding increase in availability ofsynthetic routes into these target molecules. It therefore becomes important to design new sidechain protection strategies for selenocysteine as well as multiple and novel deprotection chemistry for their removal. In this paper, we outline the synthesis of two new Fmoc selenocysteine derivatives [Fmoc-Sec(Meb) and Fmoc-Sec(Bzl)] to accompany the commercially available Fmoc-Sec(Mob) derivative and incorporate them into two model peptides. Sec-deprotection assays were carried out on these peptides using 2,2'-dithiobis(5-nitropyridine) (DTNP) conditions previously described by our group. The deprotective methodology was further evaluated as to its suitability towards mediating concurrent diselenide formation in oxytocin-templated target peptides. Sec(Mob) and Sec(Meb) were found to be extremely labile to the DTNP conditions whether in the presence or absence of thioanisole, whereas Sec(Bzl) was robust to DTNP in the absence of thioanisole but quite labile in its presence. In multiple Sec-containing model peptides, it was shown that bis-Sec(Mob)-containing systems spontaneously cyclize to the diselenide using 1 eq DTNP, whereas bis-Sec(Meb) and Sec(Bzl) models required additional manipulation to induce cyclization. Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.

Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.

PMID:
22249911
[PubMed - as supplied by publisher]
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7.
Mycopathologia. 2012 Jan 17. [Epub ahead of print]

Synthetic Peptides Mimic gp75 from Paracoccidioides brasiliensis in the Diagnosis of Paracoccidioidomycosis.

Source

Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo-Escola Paulista de Medicina, Disciplina de Imunologia, Rua Botucatu, 862, 4º andar, São Paulo, 04023-900, Brazil.

Abstract

Paracoccidioidomycosis (PCM) is a systemic granulomatous disease, endemic in Latin America, caused by the thermal dimorphic fungus Paracoccidioides brasiliensis. Although some fungal antigens have already been characterized and used for serological diagnosis, cross-reactions have been frequently observed. Thus, the examination of fungal forms in clinical specimens or isolation of P. brasiliensis by culture is still the most frequent method for the diagnosis of this mycosis. In this study, a random peptide phage display library was used to select mimotopes of P. brasiliensis, which were employed as antigens in an indirect enzyme-linked immunosorbent assay. The protective monoclonal antibody against experimental PCM (anti-gp75) was used as molecular target to screen a phage display library. That approach led to a synthetic peptide named P2, which was synthesized and tested against PCM patients' sera to check whether it was recognized. There was significant recognition of P2 by sera of untreated PCM patients when compared with normal human sera. Sera from treated PCM group, patients with other mycosis or co-infected with HIV had much lower recognition of P2 than untreated patient group. The test showed a sensitivity of 100 and 94.59% of specificity in relation to human sera control. These data indicate a potential use of P2 as diagnostic tool in PCM. Its application for serological diagnosis of PCM may contribute to the development and standardization of simpler, faster and highly reproducible immunodiagnostic tests at low cost.

PMID:
22249604
[PubMed - as supplied by publisher]
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8.
Plant Cell. 2012 Jan 13. [Epub ahead of print]

The Apoplastic Oxidative Burst Peroxidase in Arabidopsis Is a Major Component of Pattern-Triggered Immunity.

Source

School of Biological Sciences, Royal Holloway, University of London, Egham, Surrey TW20 0EX, United Kingdom.

Abstract

In plants, reactive oxygen species (ROS) associated with the response to pathogen attack are generated by NADPH oxidases or apoplastic peroxidases. Antisense expression of a heterologous French bean (Phaseolus vulgaris) peroxidase (FBP1) cDNA in Arabidopsis thaliana was previously shown to diminish the expression of two Arabidopsis peroxidases (peroxidase 33 [PRX33] and PRX34), block the oxidative burst in response to a fungal elicitor, and cause enhanced susceptibility to a broad range of fungal and bacterial pathogens. Here we show that mature leaves of T-DNA insertion lines with diminished expression of PRX33 and PRX34 exhibit reduced ROS and callose deposition in response to microbe-associated molecular patterns (MAMPs), including the synthetic peptides Flg22 and Elf26 corresponding to bacterial flagellin and elongation factor Tu, respectively. PRX33 and PRX34 knockdown lines also exhibited diminished activation of Flg22-activated genes after Flg22 treatment. These MAMP-activated genes were also downregulated in unchallenged leaves of the peroxidase knockdown lines, suggesting that a low level of apoplastic ROS production may be required to preprime basal resistance. Finally, the PRX33 knockdown line is more susceptible to Pseudomonas syringae than wild-type plants. In aggregate, these data demonstrate that the peroxidase-dependent oxidative burst plays an important role in Arabidopsis basal resistance mediated by the recognition of MAMPs.

PMID:
22247251
[PubMed - as supplied by publisher]
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9.
ChemMedChem. 2012 Jan 13. doi: 10.1002/cmdc.201100542. [Epub ahead of print]

A Synthetic C34 Trimer of HIV-1 gp41 Shows Significant Increase in Inhibition Potency.

Source

Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kandasurugadai, Chiyoda-ku, Tokyo 101-0062 (Japan).

Abstract

Supramolecular interference: A synthetic peptide mimetic of the trimeric form of gp41 showed significantly increased inhibitory activity against the HIV-1 fusion mechanism. This study demonstrates a useful strategy for the design of effective inhibitors against viral infections that proceed by membrane fusion with host cells.

Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

PMID:
22247043
[PubMed - as supplied by publisher]
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10.
J Leukoc Biol. 2012 Jan 13. [Epub ahead of print]

The role of the Src family kinase Lyn in the immunomodulatory activities of cathelicidin peptide LL-37 on monocytic cells.

Source

Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada.

Abstract

Cathelicidin LL-37 is a multifunctional, immunomodulatory and antimicrobial host-defense peptide of the human immune system. Here, we identified the role of SFKs in mediating the chemokine induction activity of LL-37 in monocytic cells. LL-37 induced SFK phosphorylation; and chemical inhibitors of SFKs suppressed chemokine production in response to LL-37 stimulation. SFKs were required for the downstream activation of AKT, but Ca(2+)-flux and MAPK induction were SFK-independent. Through systematic siRNA knockdown of SFK members, a requirement for Lyn in mediating LL-37 activity was identified. The involvement of Lyn in cathelicidin activities was further confirmed using Lyn-knockout mouse BMDMs. The role of SFKs and Lyn was also demonstrated in the activities of the synthetic cationic IDR peptides, developed as novel, immunomodulatory therapeutics. These findings elucidate the common molecular mechanisms mediating the chemokine induction activity of natural and synthetic cationic peptides in monocytic cells and identify SFKs as a potential target for modulating peptide responses.

PMID:
22246800
[PubMed - as supplied by publisher]
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11.
Glycoconj J. 2012 Jan 14. [Epub ahead of print]

One-step immunopurification and lectinochemical characterization of the Duffy atypical chemokine receptor from human erythrocytes.

Source

Department of Immunochemistry, Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, R. Weigla 12, 53-114, Wrocław, Poland.

Abstract

Duffy antigen/receptor for chemokines (DARC) is a glycosylated seven-transmembrane protein acting as a blood group antigen, a chemokine binding protein and a receptor for Plasmodium vivax malaria parasite. It is present on erythrocytes and endothelial cells of postcapillary venules. The N-terminal extracellular domain of the Duffy glycoprotein carries Fy(a)/Fy(b) blood group antigens and Fy6 linear epitope recognized by monoclonal antibodies. Previously, we have shown that recombinant Duffy protein expressed in K562 cells has three N-linked oligosaccharide chains, which are mainly of complex-type. Here we report a one-step purification method of Duffy protein from human erythrocytes. DARC was extracted from erythrocyte membranes in the presence of 1% n-dodecyl-β-D-maltoside (DDM) and 0.05% cholesteryl hemisuccinate (CHS) and purified by affinity chromatography using immobilized anti-Fy6 2C3 mouse monoclonal antibody. Duffy glycoprotein was eluted from the column with synthetic DFEDVWN peptide containing epitope for 2C3 monoclonal antibody. In this single-step immunoaffinity purification method we obtained highly purified DARC, which migrates in SDS-polyacrylamide gel as a major diffuse band corresponding to a molecular mass of 40-47 kDa. In ELISA purified Duffy glycoprotein binds anti-Duffy antibodies recognizing epitopes located on distinct regions of the molecule. Results of circular dichroism measurement indicate that purified DARC has a high content of α-helical secondary structure typical for chemokine receptors. Analysis of DARC glycans performed by means of lectin blotting and glycosidase digestion suggests that native Duffy N-glycans are mostly triantennary complex-type, terminated with α2-3- and α2-6-linked sialic acid residues with bisecting GlcNAc and α1-6-linked fucose at the core.

PMID:
22246380
[PubMed - as supplied by publisher]
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12.
Vaccine. 2012 Jan 12. [Epub ahead of print]

A novel tick antigen shows high vaccine efficacy against the dog tick, Rhipicephalus sanguineus.

Source

Animal Biotechnology Department, Center for Genetic Engineering and Biotechnology, 31th Avenue and 190, P.O. Box 6162, Havana 10600, Cuba.

Abstract

Ticks are acaridae ectoparasites that, while taking a blood meal, can transmit viruses, bacteria, protozoa and filarial nematodes, which cause a variety of human and animal illnesses. The use of chemical pesticides constitutes the primary measure for control of these ectoparasites. However, the intensive use of these chemicals has drawbacks such as the contamination of food, environmental pollution and development of resistance by ectoparasites. Vaccination is considered a promising alternative for controlling infestations by ectoparasites. Although emerging tick proteins have been identified recently, and have been proposed as potential targets for generating protective molecules, only a limited number of them have been evaluated in vaccine trials. More than 80 proteins are found in eukaryotic ribosomes. The protein P0 is essential for the assembly of the 60S ribosomal subunit. We have identified an immunogenic region of the ribosomal protein P0 from Rhipicephalus sp. ticks that is not very conserved compared to host P0. The efficacy of a 20 amino acid synthetic peptide from this sequence was assayed as a vaccine antigen against Rhipicephalus sanguineus infestations in an immunization and challenge experiment on rabbits. A remarkable diminution in the viability of newly molted nymphs from larvae fed on vaccinated rabbits was observed. The number of adults and the number of eggs hatching were significantly reduced, with an overall efficacy of 90%. Our results demonstrated that immunization with an immunogenic peptide of tick protein P0 greatly reduced survival of ticks, suggesting that it has promise as an effective tick control agent.

Copyright © 2012. Published by Elsevier Ltd.

PMID:
22245603
[PubMed - as supplied by publisher]
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13.
J Mol Biol. 2012 Jan 10. [Epub ahead of print]

Non-Stressful Death of 23S rRNA Mutant G2061C Defective in Puromycin Reaction.

Source

Department of Chemistry and A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russia; Research Institute for Physical-Chemical Medicine of Federal Medico-Biological Agency of Russian Federation, 119992 Malaya Pirogovskaya 1a, Moscow, Russia.

Abstract

Catalysis of peptide bond formation in the peptidyl transferase center is a major enzymatic activity of the ribosome. Mutations limiting peptidyl transferase activity are mostly lethal. However, cellular processes triggered by peptidyl transferase deficiency in the bacterial cell are largely unknown. Here we report a study of the lethal G2061C mutant of Escherichia coli 23S ribosomal RNA (rRNA). The G2061C mutation completely impaired the puromycin reaction and abolished formation of the active firefly luciferase in an in vitro translation system, while poly(U)- and short syntheticmRNA-directed peptidyl transferase reaction with aminoacylated tRNAs in vitro was seemingly unaffected. Study of the cellular proteome upon expression of the 23S rRNA gene carrying the G2061C mutation compared to cells expressing wild-type 23S rRNA gene revealed substantial differences. Most of the observed effects in the mutant were associated with reduced expression of stress response proteins and particularly proteins associated with the ppGpp-mediated stringent response.

Copyright © 2012. Published by Elsevier Ltd.

PMID:
22245576
[PubMed - as supplied by publisher]
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14.
Biophys Chem. 2011 Dec 24. [Epub ahead of print]

Characterization of channel-forming peptide nanostructures.

Abstract

We have prepared fluorescent analogs of known ion-channel-forming synthetic peptide nanostructures. These analogs were designed as probes to gain insight about the mechanism by which self-assembling amphiphilic peptides interact with lipid membranes. Conformational studies demonstrated that the labeled analogs retain their propensity to adopt a strong helical conformation in 2,2,2-trifluoroethanol and lipid bilayers. Attenuated total reflectance results indicated that the fluorescent peptide nanostructures are under an incorporation equilibrium between two forms, adsorbed at the surface or incorporated within the bilayer, similar to their unlabeled counterparts. However, when using a HeLa mimicking membrane, the proportion of peptide nanostructures in the transmembrane orientation decreases significantly. Finally, we were able to show by confocal microscopy studies that fluorescent analogs internalized into HeLa cells and localized into both the membranes of inner organelles and the cell membrane.

Copyright © 2011 Elsevier B.V. All rights reserved.

PMID:
22245249
[PubMed - as supplied by publisher]
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15.
Biochem Biophys Res Commun. 2012 Jan 8. [Epub ahead of print]

Extracellular acidosis accelerates bone resorption by enhancing osteoclast survival, adhesion, and migration.

Source

Department of Microbiology, Aging-associated Vascular Disease Research Center, Yeungnam University College of Medicine, Daegu 705-717, Republic of Korea.

Abstract

Acidic extracellular pH promotes osteoporotic bone loss by osteoclast activation. However, the change of osteoclastic cell behavior in acidosis-stimulated bone resorption process is unknown. We found that lowering extracellular pH induced an increase in the survival, adhesion, and migration of mature osteoclasts with a full actin ring, leading to enhanced pit formation on dentine slices. Acidosis upregulated osteopontin, which is an Arg-Gly-Asp (RGD) motif-containing matrix protein secreted from osteoclasts and acts as a common modulator for their survival, adhesion, and migration. A synthetic RGD peptide treatment blocked acidosis-induced osteoclast adhesion and migration, likely by competing with the RGD motif-containing extracellular matrix proteins for cell surface integrin binding. We finally observed that acidosis was associated with activation of osteoclast survival/adhesion/migration-related Pyk2, Cbl-b, and Src signals. Collectively, the findings indicate that extracellular acidosis stimulates bone resorption by extending osteoclast survival and facilitating osteoclast adhesion and migration.

Copyright © 2012. Published by Elsevier Inc.

PMID:
22244876
[PubMed - as supplied by publisher]
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16.
Anal Chem. 2012 Jan 5. [Epub ahead of print]

A General LC-MS/MS Method Approach to Quantify Therapeutic Monoclonal Antibodies Using a Common Whole Antibody Internal Standard with Application to Preclinical Studies.

Abstract

Ligand binding assays (LBAs) are widely used for monoclonal antibody (mAb) Ligand binding assays (LBAs) are widely used for therapeutic monoclonal antibody (mAb) quantification in biological samples. Major limitations are long method development times, reagent procurement, and matrix effects. LC-MS/MS methods using signature peptides are emerging as an alternative approach, which typically use a stable isotope labeled signature peptide as the internal standard (IS). However, a new IS has to be generated for every candidate, and the IS may not correct for variations at all processing steps. We have developed a general LC-MS/MS method approach employing a uniformly heavy-isotope labeled common whole mAb IS and a common immunocapture for sample processing. The method was streamlined with automation for consistency and throughput. Method qualification of four IgG2 and four IgG1 mAbs showed sensitivity of 0.1 µg/mL and linearity of 0.1-15 µg/mL. Quality control (QC) data of these eight mAbs were accurate and precise. The QC performance of the whole molecule labeled IS was better than those of synthetic labeled IS peptidestested. The pharmacokinetic results of two mAbs (an IgG2 and IgG1 candidate) dosed in rats were comparable to those of LBA. The general LC-MS/MS method approach overcomes the limitations of current methods to reduce time and resources required for preclinical studies.

PMID:
22243404
[PubMed - as supplied by publisher]
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17.
Langmuir. 2012 Jan 14. [Epub ahead of print]

Promoting Self-Assembly of Collagen-Related Peptides into Various Higher-Order Structures by Metal-Histidine Coordination.

Abstract

Collagen is an important and widely used biomaterial and therapeutic. The construction of large-scale collagen structures via the self-assembly of small collagen-related peptides has been extensively studied in the last decade. Here, we report a highly effective and simple means to assemble small synthetic collagen-related peptides into various higher-order structures by utilizing metal-histidine coordination. In this work, two short collagen-related peptides in which histidine residues were incorporated as metal binding sites were designed and chemically synthesized: HG(PPG)9GH (X9) and HG(PPG)4(PHG)(PPG)4GH (PHG). Circular dichroism measurements indicated that these two peptides form only marginally stable collagen triple helices but that their stability can be increased upon the addition of metal ions. Dynamic light scattering analyses, turbidity measurements, TEM, and SEM results demonstrated the metal ion-dependent self-assembly of X9 and PHG into supramolecular structures ranging from various nano-fibrils to micro-scale spherical, laminated, and granulated assemblies. The topology and size of these higher-order structures depends both on the metal ion identity and the location of the binding sites. Most intriguingly, the assembled fibrils show similar D-periodicity to that of natural collagen. Our results demonstrate that metal-histidine coordination can serve as an effective force to induce the self-assembly of unstable collagen-related peptides into higher-order structures.

PMID:
22243030
[PubMed - as supplied by publisher]
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18.
J Biol Chem. 2012 Jan 12. [Epub ahead of print]

Human Protein Arginine Methyltransferase 7 (PRMT7) is a Type III Enzyme Forming ω-NG-Monomethylated Arginine Residues.

Source

UCLA, United States.

Abstract

Full-length human protein arginine methyltransferase 7 (PRMT7) expressed as a fusion protein in Escherichia coli was initially found to generate only ω-N(G) monomethylated arginine residues in small peptides, suggesting that it is a type III enzyme. A later study, however, characterized fusion proteins of PRMT7 expressed in bacterial and mammalian cells as a type II/type I enzyme, capable of producing symmetrically dimethylated arginine (type II activity) as well as small amounts of asymmetric dimethylarginine (type I activity). We have sought to clarify the enzymatic activity of human PRMT7. We analyzed the in vitro methylation products of a glutathione-S-transferase (GST)-PRMT7 fusion protein with robust activity using a variety of arginine-containing synthetic peptides and protein substrates, including a GST-fusion with the N-terminal domain of fibrillarin (GST-GAR), myelin basic protein and recombinant human histones H2A, H2B, H3, and H4. Regardless of methylation reaction conditions (incubation time, reaction volume and substrate concentration), we found that PRMT7 only produces ω-N(G)-monomethylarginine with these substrates. In control experiments, we showed that mammalian GST-PRMT1 and Myc-PRMT5 were, unlike PRMT7, able to dimethylate bothpeptide P-SmD3 and SmB/D3 to give the expected asymmetric and symmetric products, respectively. These experiments show that PRMT7 is indeed a type III human methyltransferase capable of forming only ω-N(G)-monomethylarginine, not ADMA or SDMA, under the conditions tested.

PMID:
22241471
[PubMed - as supplied by publisher]
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19.
J Proteome Res. 2012 Jan 13. [Epub ahead of print]

Enhanced Separation and Characterization of Deamidated Peptides with RP-ERLIC-based Multidimensional Chromatography Coupled with Tandem Mass Spectrometry.

Abstract

Deamidation of asparaginyl residues in proteins produces a mixture of asparaginyl, n-aspartyl and isoaspartyl residues, which affects the proteins' structure, function and stability. Thus, it is important to identify and quantify the products to evaluate the effects in biological systems. It is still a challenging task to distinguish between the n-Asp and isoAsp deamidation products in a proteome-wide analysis due to their similar physicochemical properties. The quantification of the isomeric deamidated peptides is also rather difficult due to their coelution/poor separation in reverse-phase liquid chromatography (RPLC). We here propose a RP-ERLIC-MS/MS approach for separating and quantifying on a proteome-wide scale the three products related to deamidation of the same peptide. The key to the method is the use of RPLC in the first dimensional separation and ERLIC (electrostatic repulsion-hydrophilic interaction chromatography) in the second, with direct online coupling to tandem MS. The coelution of the three deamidation-related peptides in RPLC is then an asset, as they are collected in the same fraction. They are then separated and identified in the second dimension with ERLIC, which separates peptides based on both pI and GRAVY values. The coelution of the three products in RPLC and their efficient separation in ERLIC were validated using synthetic peptides, and the performance of ERLIC-MS/MS was tested using peptide mixtures from two proteins. Applying this sequence to rat liver tissue, we identified 302 unique N-deamidated peptides, of which 20 were identified via all three deamidation-related products and 70 of which were identified via two of them.

PMID:
22239700
[PubMed - as supplied by publisher]
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20.
ACS Chem Biol. 2012 Jan 12. [Epub ahead of print]

Template-Assisted and Self-Activating Clicked Peptide as a Synthetic Mimic of the SH2 Domain.

Abstract

A new synthetic strategy for obtaining artificial receptors that selectively regulate and/or control specific protein/protein interactions was developed based on the template-assisted and the self-activating click reaction applied to a combinatorial library. Synthetic mimics of the Grb2-SH2 domain, examined as a model case, selectively bound to a target signaling protein to induce cytotoxicity and inhibit tumor growth in vivo. synthetic peptide| What issynthetic peptide |Papers on synthetic peptide|Research on synthetic peptide| Publications on synthetic peptide

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