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At least 883 records · Page 49Linked to original sources
PubMed2004

Characterization of a region involved in binding of measles virus H protein and its receptor SLAM (CD150).

Signaling lymphocyte activation molecule (SLAM; also known as CD150) is a newly identified cellular receptor for measles virus (MV). MV Hemagglutinin protein (H) mediates MV entry into host cells by specifically binding to SLAM. Amino acid 27-135 of SLAM was previously shown to be the functional domain to interact with H and used to screen a 10-mer phage display peptide library in this study. After four rounds of screening and sequence analysis, the deduced amino acid sequence of screened peptides SGFDPLITHA and SDWDPLFTHK showed to be highly homologous with amino acid 429-438 of MV H (SGFGPLITHG). Peptides SGFDPLITHA and SDWDPLFTHK specifically inhibited binding of H to SLAM and further inhibition of MV infection suggests that these peptides can be developed to MV blocking reagents and amino acid 429-438 in H protein is functionally involved in receptor binding and may constitute part of the receptor-binding determinants on H protein.

Animals↗
PubMed2004

Facile synthesis of metal-chelating peptides on chip for protein array.

A unique peptide sequence of HGGHHG screening from a combinatorial synthetic peptide library showed a good chelating ability to bind a transition metal on a chip better than hexa-His peptide. It was directly conjugated with a His-Tagged proteins onto a chip in a mild aqueous solution and can be used this chip as a high throughput technique for protein array in order to detect and purify the His-Tagged proteins.

Chelating Agents↗
PubMed2006

Phage-displayed peptides having antigenic similarities with porcine epidemic diarrhea virus (PEDV) neutralizing epitopes.

Seven-mer phage random peptide libraries were panned against 2C10, a monoclonal antibody that showed neutralizing activities against PEDV. Recombinant M13 phages displaying the peptides SHRLP(Y/Q)(P/V) or GPRPVTH on the g3p minor coat protein showed strong binding affinity with 2C10 (70% and 30% of recovered phages, respectively) after multiple panning. Sequence analysis suggested that these peptides are similar with (1368)GPRLQPY(1374) found at the carboxy-terminal of the S protein. In neutralization inhibition assays, the two peptide motifs and a 24-mer synthetic peptide corresponding to the C-terminal endodomain of PEDV S protein were observed to compete for the antigen binding site of 2C10, as demonstrated by the loss or reduction of neutralizing activity of the monoclonal antibody. This new finding suggests that the newly discovered peptide motifs mimic a neutralizing epitope PEDV.

Amino Acid Motifs↗
PubMed2005

Identification of an immunogenic EWS-FLI1-derived HLA-DR-restricted T helper cell epitope.

Immunotherapy with tumor-specific peptide-loaded dendritic cells represents a promising therapeutic approach for patients with multifocal primary or early relapsed Ewing family tumors (EFT). The authors therefore screened a peptide library derived from the fusion region of the EFT-specific chimeric transcription factor EWS-FLI1 for immunogenic peptides. T-cell priming with 10 peptides was evaluated using IFN(gamma) video-assisted automated enzyme-linked immunospot technique. The authors report the identification of the first EFT-specific immunogenic T-cell epitope so far. Its identification will lead to a better understanding of EFT immunology and may improve DC-based immunotherapy.

Amino Acid Sequence↗
PubMed2006

Characterization of an FcgammaRI-binding peptide selected by phage display.

The high-affinity IgG receptor, Fcgamma receptor I (FcgammaRI), is expressed exclusively on myeloid cells, and there is a great interest in the targeting of vaccine antigens to FcgammaRI using anti-human FcgammaRI antibodies or fragments derived from such molecules. In order to reduce the size and complexity of the targeting reagent, we have searched for FcgammaRI binding peptides in peptide libraries displayed on phage. The human monocytic cell line U937 was used as target. Phages that displayed the consensus peptide CLRSGXGC were selected and revealed increased binding to IFN-gamma stimulated versus non-stimulated U937 cells as well as to FcgammaRI transfected versus non-transfected IIA1.6 cells. Furthermore, they bound the extracellular domains of soluble FcgammaRI, but neither FcgammaRIIA, FcgammaRIIB nor FcgammaRIIIB. Binding was inhibited by a synthetic version of the peptide, whereas neither human IgG nor the FcgammaRI-specific monoclonal antibodies (mAb) mAb22 and 32.2 interfered. Flow-cytometry analysis and internalization studies showed that a synthetic biotin-conjugated peptide ADGACLRSGRGCGAAK-bio was able to target U937 cells and FcgammaRI transfected IIA1.6 cells, and further to promote internalization and vesicular degradation of streptavidin coupled to 1 microm magnetic beads. These peptides may have potential as FcgammaRI targeting reagents.

Antibodies, Monoclonal↗
PubMed2003

Trapping of peptide-based surrogates in an artificially created channel of cytochrome c peroxidase.

As recently described, the deliberate removal of the proposed electron transfer pathway from cytochrome c peroxidase resulted in the formation of an extended ligand-binding channel. The engineered channel formed a template for the removed peptide segment, suggesting that synthetic surrogates might be introduced to replace the native electron transfer pathway. This approach could be united with the recent development of sensitizer-linked substrates to initiate and study electron transfer, allowing access to unresolved issues about redox mechanism of the enzyme. Here, we present the design, synthesis, and screening of a peptide library containing natural and unnatural amino acids to identify the structural determinants for binding this channel mutant. Only one peptide, (benzimidazole-propionic acid)-Gly-Ala-Ala, appeared to interact, and gave evidence for both reversible and kinetically trapped binding, suggesting multiple conformations for the channel protein. Notably, this peptide was the most analogous to the removed electron transfer sequence, supporting the use of a cavity-template strategy for design of specific sensitizer-linked substrates as replacements for the native electron transfer pathway.

Cytochrome-c Peroxidase↗
PubMed1996

Recovery of high-affinity phage from a nitrostreptavidin matrix in phage-display technology.

A novel approach for the selection of high-affinity phage from phage-peptide libraries is described. The methodology employs a chemically modified form of streptavidin, termed nitrostreptavidin, which exhibits a reversible attraction for biotin. The new approach emulates conventional procedures in that a biotinylated probe, in this case biotinylated alpha-bungarotoxin, is attached to an immobilized streptavidin matrix. The phage library is introduced, and interacting phage particles are released under conventional acidic conditions (pH 2.2). At this stage, the primary peptide sequences characterizing the released phage are found to be identical with those previously known to interact with the toxin. However, other phage particles, which presumably interact more strongly than those released by acid, remain attached to the immobilized toxin. These can be released by virtue of the reversible biotin-binding properties of nitrostreptavidin. For this purpose, alkaline solutions (pH 10) or free biotin can be used. Using this approach, phage particles that recognize alpha-bungarotoxin were isolated; their peptide sequences were found to be similar to, but clearly distinct from, those collected by conventional acid elution. The affinity of the isolated phage was dramatically higher than that of phage obtained by the conventional methodology. In contrast, their synthetically prepared 15-mer peptides actually exhibited a lower affinity for the toxin than that shown by peptides prepared on the basis of the sequence obtained from conventional acid-eluted phage. This apparent discrepancy can be explained by an altered conformational state of the peptides in solution, compared to the epitopes expressed in situ on the phage surface.

Adsorption↗
PubMed2004

The binding specificity of OppA determines the selectivity of the oligopeptide ATP-binding cassette transporter.

The purification and functional reconstitution of a five-component oligopeptide ATP-binding cassette transporter with a remarkably wide substrate specificity are described. High-affinity peptide uptake was dependent on liganded substrate-binding protein OppA, which interacts with the translocator OppBCDF with higher affinity than unliganded OppA. Transport screening with combinatorial peptide libraries revealed that (i) the Opp transporter is not selective with respect to amino acid side chains of the transported peptides; (ii) any peptide that can bind to OppA is transported via Opp, including very long peptides up to 35 residues long; and (iii) the binding specificity of OppA largely determines the overall transport selectivity.

Adenosine Triphosphate↗
PubMed2002

Selection of peptide ligands binding to the basolateral cell surface of proximal convoluted tubules.

BACKGROUND: Recently, we have reported a novel approach of screening phage-display peptide libraries on microdissected intact renal tubular segments and identified an RGD-containing peptide ligand that specifically binds to the basolateral membrane of cortical collecting ducts (CCD). However, screening phage libraries on proximal convoluted tubules (PCT) did not yield a tubule segment-specific ligand. Here, we describe the successful modification of our previously developed phage-display approach and the identification of two distinct ligands that bind specifically to receptors expressed at the basolateral membrane of PCT. METHODS: Ex vivo screening of phage-display peptide libraries for specific ligands was adapted for PCT. The previously developed method was significantly extended by applying it to a distinct tubular segment, varying the number of rounds of biopanning and incubating phage libraries with absorber cells prior to biopanning. Binding specificity and cellular localization of selected peptide-displaying phage or the corresponding synthetic peptide were analyzed using various epithelial cell lines as well as competition assays and confocal immunofluorescence microscopy. RESULTS: Screening phage-display peptide libraries, depleted of ligands binding to ubiquitously expressed receptors by preincubation with HEK-293 cells, led to the identification of two PCT-specific ligands. Phage expressing peptides with the consensus sequence GV(K/R)GX3(T/S) or RDXR mediated 15-fold and 13-fold higher binding to PCT than control phage, and binding to PCT was 13-fold and 21-fold higher than binding to CCD, respectively. Neither phage mediated significant binding to various epithelial cell lines, and binding of both ligands was abolished by the addition of the corresponding synthetic peptide. Immunofluorescence experiments revealed a submembrane localization of both ligands upon incubation with PCT. CONCLUSIONS: Exploiting the versatility of phage-display and biopanning allowed the identification of two distinct peptide ligands that bind specifically to the basolateral membrane of PCT. Tubule segment-specific ligands, such as the described PCT ligands, may be useful for the analysis of cell-extracellular matrix interactions and may contribute to the development of new therapeutic strategies for renal diseases.

Amino Acid Sequence↗
PubMedDate not supplied

An unconventional IAP-binding motif revealed by target-assisted iterative screening (TAIS) of the BIR3-cIAP1 domain.

Target-assisted iterative screening (TAIS) has been applied to a random phage-displayed peptide library in a search for novel ligands of the third baculovirus IAP ('inhibitors of apoptosis') repeat (BIR) domain of cIAP1. The peptides selected in the screen fall into two distinct specificity groups, one that conforms to a known IAP-binding motif (IBM) and another one that reveals a novel BIR domain interacting motif, NH(2)-SR(V/P)W. The biochemical profiling of selected sequences with synthetic peptides, which included alanine scanning and N- and C-terminal truncations as well as competition with the Smac peptide, suggests a major energetic contribution of tryptophan at the +4 position of peptide ligands to binding and identifies the latter together with the respective pocket on the BIR domain surface as a 'hot spot' of the interaction. A peptide featuring the novel motif selectively binds the full-length cIAP1 protein in cell lysates. A 'two-pocket' model of BIR domain recognition mechanism is proposed as the basis of differential BIR domain interactions with different IBMs.

Amino Acid Motifs↗
PubMed2004

In vivo targeting of organic calcium sensors via genetically selected peptides.

A library of constrained peptides that form stable folded structures was screened for aptamers that bind with high affinity to the fluorescent dye Texas red. Two selected clones had binding constants to Texas red of 25 and 80 pM as phage and binding had minimal effects on the fluorescence of Texas red. The peptides interact with distinct but overlapping regions of Texas red. One peptide bound to X-rhod calcium sensors, which share the same core fluorophore as Texas red. These dyes retained calcium sensitivity when bound to the peptide. This peptide was used to label a fusion protein with X-rhod-5F in vivo, and X-rhod sensed changes in calcium locally. Thus, minimal, constrained peptides can functionally bind to environmentally sensitive dyes or other organic agents in biological contexts, suggesting tools for in vivo imaging and analysis.

Amino Acid Sequence↗
PubMed2003

The discovery of catalytically active peptides through combinatorial chemistry.

In recent years, ogliopeptides have enjoyed ever increasing interest in two areas: first, approaches to biomimetic enzyme-like activity; and second, as metal-free catalysts for enantioselective transformations of synthetic interest. The discovery and optimization of peptides for these purposes has often used the methodology of combinatorial chemistry. Examples include the screening of peptide libraries for ester and phosphate cleavage, aided by novel chromogenic and gel-based assays, and optimization of metal-free peptide catalysts for asymmetric epoxidation, enantioselective acylation/phosphorylation, conjugate addition to enimides, and hydrocyanation of imines (Strecker-reaction).

Acylation↗
PubMed2000

Highly specific, membrane-permeant peptide blockers of cGMP-dependent protein kinase Ialpha inhibit NO-induced cerebral dilation.

Arrays of octameric peptide libraries on cellulose paper were screened by using (32)P-autophosphorylated cGMP-dependent protein kinase Ialpha (cGPK) to identify peptide sequences with high binding affinity for cGPK. Iterative deconvolution of every amino acid position in the peptides identified the sequence LRK(5)H (W45) as having the highest binding affinity. Binding of W45 to cGPK resulted in selective inhibition of the kinase with K(i) values of 0.8 microM and 560 microM for cGPK and cAMP-dependent protein kinase (cAPK), respectively. Fusion of W45 to membrane translocation signals from HIV-1 tat protein (YGRKKRRQRRRPP-LRK(5)H, DT-2) or Drosophila Antennapedia homeo-domain (RQIKIWFQNRRMKWKK-LRK(5)H, DT-3) proved to be an efficient method for intracellular delivery of these highly charged peptides. Rapid translocation of the peptides into intact cerebral arteries was demonstrated by using fluorescein-labeled DT-2 and DT-3. The inhibitory potency of the fusion peptides was even greater than that for W45, with K(i) values of 12.5 nM and 25 nM for DT-2 and DT-3, respectively. Both peptides were still poor inhibitors of cAPK. Selective inhibition of cGPK by DT-2 or DT-3 in the presence of cAPK was demonstrated in vitro. In pressurized cerebral arteries, DT-2 and DT-3 substantially decreased NO-induced dilation. This study provides functional characterization of a class of selective cGPK inhibitor peptides in vascular smooth muscle and reveals a central role for cGPK in the modulation of vascular contractility.

Animals↗
PubMed2001

Identification of B-cell epitope of dengue virus type 1 and its application in diagnosis of patients.

Using a serotype-specific monoclonal antibody (MAb) of dengue virus type 1 (DEN-1), 15F3-1, we identified the B-cell epitope of DEN-1 from a random peptide library displayed on phage. Fourteen immunopositive phage clones that bound specifically to MAb 15F3-1 were selected. These phage-borne peptides had a consensus motif of HxYaWb (a = S/T, b = K/H/R) that mimicked the sequence HKYSWK, which corresponded to amino acid residues 111 to 116 of the nonstructural protein 1 (NS1) of DEN-1. Among the four synthetic peptides corresponding to amino acid residues 110 to 117 of the NS1 of DEN-1, -2, -3, and -4, only one peptide, EHKYSWKS (P14M) of DEN-1, was found to bind to 15F3-1 specifically. Furthermore, P14M was shown to inhibit the binding of phage particles to 15F3-1 in a competitive inhibition assay. Histidine(111) (His(111)) was crucial to the binding of P14M to 15F3-1, since its binding activity dramatically reduced when it changed to leucine(111) (Leu(111)). This epitope-based peptide demonstrated its clinical diagnostic potential when it reacted with a high degree of specificity with serum samples obtained from both DEN-1-infected rabbits and patients. Based on these observations, our DEN-1 epitope-based serologic test could be useful in laboratory viral diagnosis and in understanding the pathogenesis of DEN-1.

Amino Acid Sequence↗
PubMed2003

Silica-based monoliths for rapid peptide screening by capillary liquid chromatography hyphenated with electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry.

Capillary liquid chromatography based on particulate and monolithic stationary phases was used to screen complex peptide libraries by fast gradient elution coupled on-line to electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICRMS). A slightly modified commercial electrospray interface consisting of a fused-silica transfer capillary and low dead volume stainless steel union at which the electrospray voltage was grounded enabled the effluent of all the capillary columns to be directly sprayed into the mass spectrometer. Stable electrospray conditions were generated over a wide range of mobile phase compositions, alleviating the need for a tapered end of the spray capillary, pneumatic assistance or preheated nebulizer gas. Since the identification of complex samples containing numerous isobaric substances is facilitated by chromatographic separation prior to mass spectrometry, stationary phase materials have been employed which offer a fast, efficient elution and, due to the complexity of samples, a high loading capacity. Silica-based monolithic capillary columns combine these three characteristics in a unique manner due to a tailored adjustment of both macro- and mesopore sizes in the highly porous silica structure. As we demonstrate by a comparative study of the silica-based monolithic and packed capillaries for LC/MS analysis of complex peptide libraries, silica monoliths show superior performance over packed beds of small-diameter particles with respect to analysis time and separation efficiency. Libraries with more than 1000 different peptides could be screened in less than 20 min.

Chromatography, Liquid↗
PubMed2000

Targeting of phage display vectors to mammalian cells.

Phage display libraries offer a strategy to isolate peptide ligands to target proteins and to define potential interaction sites between proteins. Recent studies have indicated a novel utility for phage display in that bacteriophage engineered to express peptide ligands to specific cell surface receptors are internalized by mammalian cells. Thus, reporter genes such as green fluorescent protein and lacZ harbored in the phage genome can be delivered to mammalian cells using targeting peptides displayed on the surface of phage. There is also the possibility to generate novel types of peptide libraries expressed intracellularly using a phage capable of inducing expression of its coding genes in human cells.

Animals↗
PubMed1995

Use of peptide combinatorial libraries in drug design: the identification of a potent serotonin reuptake inhibitor derived from a tripeptide cassette library.

BACKGROUND: Medicinal chemistry traditionally requires the identification of biologically active molecules by synthesizing and screening each purified substrate. Further progress in drug discovery then requires definition of the structure-activity relationship of the lead compound. More recently, combinatorial chemistry has emerged as a way to examine structure-activity relationships by screening a large mixture of compounds synthesized in a predictably random manner, without the labor-intensive costs of molecular isolation and purification. We set out to use this approach to examine the structural requirements for peptide binding to serotonin and dopamine transporters. RESULTS: We screened a tripeptide cassette library for serotonin and dopamine reuptake inhibition using cloned transporter assay systems. The method has afforded a number of tripeptide pharmacophores with inhibitory IC50 values ranging from 10 microM to < 1 microM in the dopamine and serotonin reuptake systems. The conformation of one of these tripeptides, N-acetyl-D-Trp-L-Phe-D-Lys-CONH2 (which inhibits serotonin uptake with an IC50 of 10 microM) was compared to that of the serotonin uptake inhibitor s-fluoxetine, and was shown to be more similar in conformation to fluoxetine than was an analogous tripeptide containing L-Lys (IC50 > 50 microM). CONCLUSIONS: We have identified five tripeptides with inhibitory IC50 values of < 10 microM in the serotonin reuptake system. One tripeptide was predicted to have pharmacophore features similar to that of fluoxetine, a selective and potent non-peptide serotonin reuptake inhibitor. Our results suggest that tripeptides derived from combinatorial libraries will help to define the important structural elements of pharmacophores.

Animals↗
PubMed2007

Investigation and molecular mimicry of the antigen involved in the interaction between the monoclonal antibody 5D10 and the human breast cancer cell line MCF-7.

Monoclonal antibody (mAb) 5D10 is directed against the human breast cancer cell line MCF-7. Biochemical characterization of the antibody epitope was attempted and revealed a complex, most likely carbohydrate-linked nature, which prevented isolation and further studies of the interaction. A major goal of this work was to generate structural mimics of the 5D10 epitope to serve as putative substitutes in such studies. A peptide library displayed on filamentous phage was used to select for mimotope peptide sequences. All positive phage clones selected from the library displayed the amino acid sequence H(2)N-QMNPMYYR-CO(2)H. This peptide sequence, as well as a branched form of the peptide, was found to bind mAb 5D10. Moreover, both peptide sequences were able to inhibit the binding of 5D10 to the MCF-7 cells in a concentration-dependent manner, with an EC(50) value in the range of 65 microM. According to these results, random phage peptide libraries can serve to identify mimotopic peptides for unknown complex cell surface epitopes.

Amino Acid Sequence↗