摘要:

Improving a particular function of molecules is often more difficult than identifying such moleculesab initio. Here, a method to acquire higher affinity and/or more functional peptides was developed as a progressive library selection method. The primary library selection products were utilized to build a secondary library composed of blocks of 4 amino acids, of which selection led to peptides with increased activity. These peptides were further converted to randomly generate paired peptides. Cathepsin E‐inhibitors thus obtained exhibited the highest activities and affinities (pM order). This was also the case with cathepsin E‐activating peptides, proving the methodological effectiveness. The primary, secondary, and tertiary library selections can be regarded as module‐finding, module‐shuffling, and module‐pairing, respectively, which resembles the progression of the natural evolution of proteins. The mode of peptide binding to their target proteins is discussed in analogy to antibodies and epitopes of an antigen. Copyright © 2012 European Peptide Society and John Wiley

ISSN:1075-2617    

DOI:10.1002/psc.2453

年代:2012

数据来源: WILEY

摘要:

Radiolabeled somatostatin analogs have become powerful tools in the diagnosis and staging of neuroendocrine tumors, which express somatostatin receptors. The aim of this study was to evaluate a new somatostatin analog, 6‐hydrazinopyridine‐3‐carboxylic acid‐Ser3‐octreotate (HYNIC‐SATE) radiolabeled with99mTc, using ethylenediamine‐N,N′‐diacetic acid and tricine as coligands, to be used as a radiopharmaceutical for thein vivoimaging of somatostatin receptor subtype 2 (SSTR2)‐positive tumor. Synthesis of the peptide was carried out on a solid phase using a standard Fmoc strategy. Peptide conjugate affinities for SSTR2 were determined by receptor binding affinity on rat brain cortex and C6 cell membranes. Internalization rate of99mTc‐HYNIC‐SATE was studied in SSTR2‐expressing C6 cells that were used for intracranial tumor studies in rat brain. A reproduciblein vivoC6 glioma model was developed in Sprague–Dawley rat and confirmed by histopathology and immunohistochemical analysis. Biodistribution and imaging properties of this new radiopeptide were also studied in C6 tumor‐bearing rats. Radiolabeling was performed at high specific activities, with a radiochemical purity of>96%. Peptide conjugate showed high affinity binding for SSTR2 (HYNIC‐SATE IC50 = 1.60 ± 0.05 nm) and specific internalization into rat C6 cells. After administration of99mTc‐HYNIC‐SATE in C6 glioma‐bearing rats, a receptor specific uptake of radioactivity was observed in SSTR‐positive organs and in the implanted intracranial tumor and rapid excretion from nontarget tissues via kidneys.99mTc‐HYNIC‐SATE is a new receptor‐specific radiopeptide for targeting SSTR2‐positive brain tumor and might be of great promise in the scintigraphy of SSTR2‐positive tumors. Copyri

ISSN:1075-2617    

DOI:10.1002/psc.2458

年代:2012

数据来源: WILEY

摘要:

Myeloperoxidase (MPO) is a 150 kD tetrameric heme protein consisting of two heavy chains and two light chains, which is present in neutrophils, white blood cells, at concentrations between 2% and 5% and plays an important role in the innate immune system. The MPO concentration in serum or plasma has been shown to be linked to the risk for cardiovascular diseases, and MPO is considered to be a high potential diagnostic biomarker. To develop a molecule that binds MPO, salicylhydroxamic acid (SHA), a substrate analog inhibitor of MPO with a KD = 2 μM, was conjugated to a designed set of 42‐residue polypeptide scaffolds via 9‐ and 11‐carbon atom aliphatic spacers to form 20 different protein binder candidates, and their interactions with MPO were evaluated by surface plasmon resonance analysis. The polypeptide conjugate 4C37L34C11SHA was found to bind to MPO with an affinity that could be estimated to have a dissociation constant of around 400 pM, nearly four orders of magnitude higher than that of SHA. Inhibition of binding to MPO by free SHA was observed in competition experiments demonstrating that the binding of the polypeptide conjugate is dominated by the interactions of SHA with the heme cavity. Although still in the future, the discovery of these new synthetic binders for MPO suggests a route to clinical diagnostic testsin vivoorin vitro, independent of antibodies. Copyright © 2012 European Peptide Society and Joh

ISSN:1075-2617    

DOI:10.1002/psc.2459

年代:2012

数据来源: WILEY

摘要:

Bactenecin (Bac) is a 12‐residue disulfide‐linked antimicrobial peptide isolated from the granules of bovine neutrophils. In this study, to develop novel linear Bac analogs with cell selectivity and anti‐endotoxic activity, we designed and synthesized a series of linear Bac analogs with amino acid substitution in Cys3,11and/or Val6,7of Bac. Among Bac analogs, some analogs (Bac‐W, Bac‐KW, Bac‐L, Bac‐KL, Bac‐LW, and Bac‐KLW) with higher hydrophobicity showed the amalgamated property of cell selectivity and anti‐endotoxic activity. Furthermore, Bac‐W, Bac‐KW, Bac‐LW, and Bac‐KLW showed serum stability comparable with that of disulfide‐bonded Bac. Therefore, these Bac analogs (Bac‐W, Bac‐KW, Bac‐LW, and Bac‐KLW) can serve as promising antibiotics for the development of therapeutic agents for treatment against endotoxic shock and bacterial infection. In addition, our results suggest that a little increase in hydrophobicity may be responsible for the decreased cell selectivity of the multiple Arg‐containing peptides (Bac‐W, Bac‐L, and Bac‐LW) over the multiple Lys‐containing peptides (Bac‐KW, Bac‐KL, and Bac‐KLW). Copyright ©

ISSN:1075-2617    

DOI:10.1002/psc.2460

年代:2012

数据来源: WILEY

摘要:

Gramicidin S (GS) is a cyclic decapeptide antibiotic active against both Gram‐positive and Gram‐negative bacteria as well as against several pathogenic fungi. However, clinical application of GS is limited because of GS hemolytic activity. The large number of GS analogues with potentially attenuated hemolytic activity has been developed over the last two decades. For all new GS derivatives, the antimicrobial test is accompanied with the hemolytic activity assay. At the same time, neither GS nor its analogues were tested against other blood cells. In the present work, the effects of GS on platelets and platelet aggregates have been studied.GS interaction with platelets is concentration dependent and leads either to platelet swelling or platelet shape change. Effect of GS on platelets is independent of platelet aggregation mechanism.GS induces disaggregation of platelet aggregates formed in the presence of aggregation agonists. The rate of the GS interaction with platelet membranes depends on membrane lipid mobility and significantly increases with temperature. The interaction of GS with the platelet membranes depends strongly on the state of the membrane lipids. Factors affecting the membrane lipids (temperature, lipid peroxidation and ionising irradiation) modify GS interaction with platelets.Our results show that GS is active not only against erythrocytes but also against other blood cells (platelets). The estimated numbers of GS molecules per 1 µm2of a blood cell required to induce erythrocyte hemolysis and disaggregation of platelet aggregates are comparable. This must be considered when developing new antimicrobial GS analogues with improved hemolytic properties. Copyright © 2012 European Peptide Society and John Wiley&So

ISSN:1075-2617    

DOI:10.1002/psc.2461

年代:2012

数据来源: WILEY

摘要:

Defensins are a class of cysteine‐rich proteins, which exert broad spectrum antimicrobial activity. In this work, we used a bioinformatic approach to identify putative defensins in the tomato genome. Fifteen proteins had a mature peptide that includes the well‐conserved tetradisulfide array. We selected a representative member of the tomato defensin family; we chemically synthesized itsγ‐motif and tested its antimicrobial activity. Here, we demonstrate that the synthetic peptide exhibits potent antibacterial activity against Gram‐positive bacteria, such asStaphylococcus aureusA170,Staphylococcus epidermidis, andListeria monocytogenes, and Gram‐negative bacteria, includingSalmonella entericaserovar Paratyphi,Escherichia coli, andHelicobacter pylori. In addition, the synthetic peptide shows minimal (<5%) hemolytic activity and absence of cytotoxic effects against THP‐1 cells. Finally, SolyC exerts an anti‐inflammatory activityin vitro, as it downregulates the level of the proinflammatory cytokines TNF‐αand IFN‐γ. Copyright © 2012 European Peptide Society and

ISSN:1075-2617    

DOI:10.1002/psc.2462

年代:2012

数据来源: WILEY

摘要:

The 4‐methoxybenzyloxymethyl (MBom) group was introduced at theNπ‐position of the histidine (His) residue by using a regioselective procedure, and its utility was examined under standard conditions used for the conventional and the microwave (MW)‐assisted solid phase peptide synthesis (SPPS) with 9‐fluorenylmethyoxycarbonyl (Fmoc) chemistry. TheNπ‐MBom group fulfilling the requirements for the Fmoc strategy was found to prevent side‐chain‐induced racemization during incorporation of the His residue even in the case of MW‐assisted SPPS performed at a high temperature. In particular, the MBom group proved to be a suitable protecting group for the convergent synthesis because it remains attached to the imidazole ring during detachment of the protected His‐containing peptide segments from acid‐sensitive linkers by treatment with a weak acid such as 1% trifluoroacetic acid in dichloromethane. We also demonstrated the facile synthesis of Fmoc‐His(π‐MBom)‐OH with the aid of purification procedure by crystallization to effectively remove the undesiredτ‐isomer without resorting to silica gel column chromatography. This means that the present synthetic procedure can be used for large‐scale production without any obstacles. Copyright © 2012 European Peptid

ISSN:1075-2617    

DOI:10.1002/psc.2464

年代:2012

数据来源: WILEY