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Peptide Ligand (peptide + ligand)
Kinds of Peptide Ligand Selected AbstractsA Synthetic Peptide Ligand of Neural Cell Adhesion Molecule (NCAM) IgI Domain Prevents NCAM Internalization and Disrupts Passive Avoidance LearningJOURNAL OF NEUROCHEMISTRY, Issue 6 2000Andrew G. Foley Abstract: The neural cell adhesion molecule (NCAM) mediates cell adhesion and signal transduction through trans -homophilic- and/or cis -heterophilic-binding mechanisms. Intraventricular infusions of anti-NCAM have revealed a functional requirement of NCAM for the consolidation of memory in rats and chicks in a specific interval 6-8 h after training. We have now extended these studies to a synthetic peptide ligand of NCAM (C3) with an affinity for the IgI domain and the capability of inhibiting NCAM-mediated neurite outgrowth in vitro. Intraventricular administration of a single 5 ,g bolus of C3 strongly inhibited recall of a passive avoidance response in adult rats, when given during training or in the 6-8-h posttraining period. The effect of C3 on memory consolidation was similar to that obtained with anti-NCAM as the amnesia was not observed until the 48-h recall time. The unique amnesic action of C3 during training could be related to disrupted NCAM internalization following training. In the 3-4-h posttraining period NCAM 180, the synapse-associated isoform, was down-regulated in the hippocampal dentate gyrus. This effect was mediated by ubiquitination and was prevented by C3 administration during training. These findings indicate NCAM to be involved in both the acquisition and consolidation of a passive avoidance response in the rat. Moreover, the study provides the first in vivo evidence for NCAM internalization in learning and identifies a synthetic NCAM ligand capable of modulating memory processes in vivo. [source] Synthesis and Spectroscopic Characterization of Photo-affinity Peptide Ligands to Study Rhodopsin,G Protein Interaction,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2008Yihui Chen G protein-coupled receptors (GPCRs) are involved in the control of virtually all aspects of our behavior and physiology. Activated receptors catalyze nucleotide exchange in heterotrimeric G proteins (composed of ,·GDP, , and , subunits) on the inner surface of the cell membrane. The GPCR rhodopsin and the G protein transducin (Gt) are key proteins in the early steps of the visual cascade. The main receptor interaction sites on Gt are the C-terminal tail of the Gt,-subunit and the farnesylated C-terminal tail of the Gt,-subunit. Synthetic peptides derived from these C-termini specifically bind and stabilize the active rhodopsin conformation (R*). Here we report the synthesis of R*-interacting peptides containing photo-reactive groups with a specific isotope pattern, which can facilitate detection of cross-linked products by mass spectrometry. In a preliminary set of experiments, we characterized such peptides derived from the farnesylated Gt, C-terminus (Gt,(60-71)far) in terms of their capability to bind R*. Here, we describe novel peptides with photo-affinity labels that bind R* with affinities similar to that of the native Gt,(60-71)far peptide. Such peptides will enable an improved experimental strategy to probe rhodopsin,Gt interaction and to map so far unknown interaction sites between both proteins. [source] Reversible and Noncompetitive Inhibition of ,-Tryptase by Protein Surface Binding of Tetravalent Peptide Ligands Identified from a Combinatorial Split,Mix Library,ANGEWANDTE CHEMIE, Issue 24 2010Peter Molekulare Stöpsel: Das On-Bead-Screening einer kombinatorischen Bibliothek von 216 vierarmigen Oligopeptiden lieferte hoch spezifische, nichtkompetitive Inhibitoren der Serinprotease ,-Tryptase mit nanomolarer Affinität. Die Liganden binden sehr wahrscheinlich an die Proteinoberfläche und wirken als molekulare ,Stöpsel", indem sie den Zugang zu den aktiven Zentren blockieren, die sich im Innern einer zentralen Kavität befinden (siehe Bild). [source] Novel Peptide Ligands of RGS4 from a Focused One-Bead, One-Compound LibraryCHEMICAL BIOLOGY & DRUG DESIGN, Issue 2 2008Rebecca A. Roof Regulators of G protein signaling accelerate GTP hydrolysis by G, subunits and profoundly inhibit signaling by G protein-coupled receptors. The distinct expression patterns and pathophysiologic regulation of regulators of G protein signaling proteins suggest that inhibitors may have therapeutic potential. We previously reported the design, mechanistic evaluation, and structure,activity relationships of a disulfide-containing cyclic peptide inhibitor of RGS4, YJ34 (Ac -Val-Lys-c[Cys-Thr-Gly-Ile-Cys]-Glu- NH2, S-S) (Roof et al., Chem Biol Drug Des, 67, 2006, 266). Using a focused one-bead, one-compound peptide library that contains features known to be necessary for the activity of YJ34, we now identify peptides that bind to RGS4. Six peptides showed confirmed binding to RGS4 by flow cytometry. Two analogs of peptide 2 (Gly-Thr-c[Cys-Phe-Gly-Thr-Cys]-Trp- NH2, S-S with a free or acetylated N -terminus) inhibited RGS4-stimulated G,o GTPase activity at 25,50 ,m. They selectively inhibit RGS4 but not RGS7, RGS16, and RGS19. Their inhibition of RGS4 does not depend on cysteine-modification of RGS4, as they do not lose activity when all cysteines are removed from RGS4. Peptide 2 has been modeled to fit in the same binding pocket predicted for YJ34 but in the reverse orientation. [source] Highly Enantioselective Ruthenium-Catalyzed Reduction of Ketones Employing Readily Available Peptide LigandsCHEMISTRY - A EUROPEAN JOURNAL, Issue 1 2004Anders Bøgevig Dr. Abstract Highly efficient and selective catalysts for the asymmetric reduction of aryl alkyl ketones under hydrogen-transfer conditions (2-propanol) were obtained by combining a novel class of pseudo-dipeptide ligands with [{RuCl2(p- cymene)}2]. A library of 36 dipeptide-like ligands was prepared from N -Boc-protected ,-amino acids and the enantiomers of 2-amino-1-phenylethanol and 1-amino-2-propanol. The catalyst library was evaluated with the reduction of acetophenone and excellent enantioselectivity of 1-phenylethanol was obtained with several of the novel catalysts. A ligand based on the combination of N -Boc- L -alanine and (S)-1-amino-2-propanol (ligand A - (S)- 4) was found to be particular effective. When the situ formed ruthenium complex of this ligand was employed as the catalyst in the hydrogen-transfer reaction of various aryl alkyl ketones, the corresponding alcohol products were achieved in excellent enantioselectivity (up to 98,% ee). [source] Suboptimal engagement of the T-cell receptor by a variety of peptide,MHC ligands triggers T-cell anergyIMMUNOLOGY, Issue 1 2010Scheherazade Sadegh-Nasseri Summary T cells recognize antigen via the T-cell receptor (TCR) and produce a spectrum of responses that range from activation to anergy or cell death. The variety of outcomes may be dictated by the strength of the signals transmitted upon cognate recognition of the TCR. The physiological outcome of TCR engagement is determined by several factors, including the avidity of the ligand for TCR, the duration of engagement, and the presence and nature of accessory molecules present on antigen-presenting cells (APCs). In this review, we discuss a model of anergy induced by presentation of low densities of peptide,major histocompatibility complex (MHC) ligand in CD4+ T cells and compare it to anergy induced by altered peptide ligands in an effort to identify a unifying mechanism. We suggest that altered peptide ligand (APL) and low densities of agonist ligands induce anergy by engaging less than optimal numbers of TCRs. The physiological impacts of anergy in memory CD4+ T cells are discussed. [source] Transition metals as electron traps.JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 10 2009Abstract Transition metal cations Co2+, Ni2+ and Zn2+ form 1 : 1 : 1 ternary complexes with 2,2,-bipyridine (bpy) and peptides in aqueous methanol solutions that have been studied for tripeptides GGG and GGL. Electrospray ionization of these solutions produced singly charged [Metal(bpy)(peptide , H)]+ and doubly charged [Metal(bpy)(peptide)]2+ ions (Metal = metal ion) that underwent charge reduction by glancing collisions with Cs atoms at 50 and 100 keV collision energies. Electron transfer to [Metal(bpy)(peptide)]2+ ions was less than 4.2 eV exoergic and formed abundant fractions of non-dissociated charge-reduced intermediates. Charge-reduced [Metal(bpy)(peptide)]+ ions dissociated by the loss of a hydrogen atom, ammonia, water and ligands that depended on the metal ion. The Ni and Co complexes mainly dissociated by the elimination of ammonia, water, and the peptide ligand. The Zn complex dissociated by the elimination of ammonia and bpy. A sequence-specific fragment was observed only for the Co complex. Electron transfer to [Metal(bpy)(peptide , H)]+ was 0.6,1.6 eV exoergic and formed intermediate radicals that were detected as stable anions after a second electron transfer from Cs. [Metal(bpy)(peptide , H)] neutrals and their anions dissociated by the loss of bpy and peptide ligands with branching ratios that depended on the metal ion. Optimized structures for several spin states, electron transfer and dissociation energies were addressed by combined density functional theory and Møller,Plesset perturbational calculations to aid interpretation of experimental data. The experimentally observed ligand loss and backbone cleavage in charge-reduced [Metal(bpy)(peptide)]+ complexes correlated with the dissociation energies at the present level of theory. The ligand loss in +CR, spectra showed overlap of dissociations in charge-reduced [Metal(bpy)(peptide , H)] complexes and their anionic counterparts which complicated spectra interpretation and correlation with calculated dissociation energies. Copyright © 2009 John Wiley & Sons, Ltd. [source] A Synthetic Peptide Ligand of Neural Cell Adhesion Molecule (NCAM) IgI Domain Prevents NCAM Internalization and Disrupts Passive Avoidance LearningJOURNAL OF NEUROCHEMISTRY, Issue 6 2000Andrew G. Foley Abstract: The neural cell adhesion molecule (NCAM) mediates cell adhesion and signal transduction through trans -homophilic- and/or cis -heterophilic-binding mechanisms. Intraventricular infusions of anti-NCAM have revealed a functional requirement of NCAM for the consolidation of memory in rats and chicks in a specific interval 6-8 h after training. We have now extended these studies to a synthetic peptide ligand of NCAM (C3) with an affinity for the IgI domain and the capability of inhibiting NCAM-mediated neurite outgrowth in vitro. Intraventricular administration of a single 5 ,g bolus of C3 strongly inhibited recall of a passive avoidance response in adult rats, when given during training or in the 6-8-h posttraining period. The effect of C3 on memory consolidation was similar to that obtained with anti-NCAM as the amnesia was not observed until the 48-h recall time. The unique amnesic action of C3 during training could be related to disrupted NCAM internalization following training. In the 3-4-h posttraining period NCAM 180, the synapse-associated isoform, was down-regulated in the hippocampal dentate gyrus. This effect was mediated by ubiquitination and was prevented by C3 administration during training. These findings indicate NCAM to be involved in both the acquisition and consolidation of a passive avoidance response in the rat. Moreover, the study provides the first in vivo evidence for NCAM internalization in learning and identifies a synthetic NCAM ligand capable of modulating memory processes in vivo. [source] Low free energy cost of very long loop insertions in proteinsPROTEIN SCIENCE, Issue 2 2003Michelle Scalley-Kim Abstract Long insertions into a loop of a folded host protein are expected to have destabilizing effects because of the entropic cost associated with loop closure unless the inserted sequence adopts a folded structure with amino- and carboxy-termini in close proximity. A loop entropy reduction screen based on this concept was used in an attempt to retrieve folded sequences from random sequence libraries. A library of long random sequences was inserted into a loop of the SH2 domain, displayed on the surface of M13 phage, and the inserted sequences that did not disrupt SH2 function were retrieved by panning using beads coated with a phosphotyrosine containing SH2 peptide ligand. Two sequences of a library of 2 × 108 sequences were isolated after multiple rounds of panning, and were found to have recovery levels similar to the wild-type SH2 domain and to be relatively intolerant to further mutation in PCR mutagenesis experiments. Surprisingly, although these inserted sequences exhibited little nonrandom structure, they do not significantly destabilize the host SH2 domain. Additional insertion variants recovered at lower levels in the panning experiments were also found to have a minimal effect on the stability and peptide-binding function of the SH2 domain. The additional level of selection present in the panning experiments is likely to involve in vivo folding and assembly, as there was a rough correlation between recovery levels in the phage-panning experiments and protein solubility. The finding that loop insertions of 60,80 amino acids have minimal effects on SH2 domain stability suggests that the free energy cost of inserting long loops may be considerably less than polymer theory estimates based on the entropic cost of loop closure, and, hence, that loop insertion may have provided an evolutionary route to multidomain protein structures. [source] Comparison of binding energies of SrcSH2-phosphotyrosyl peptides with structure-based prediction using surface area based empirical parameterizationPROTEIN SCIENCE, Issue 10 2000Denise A. Henriques Abstract The prediction of binding energies from the three-dimensional (3D) structure of a protein,ligand complex is an important goal of biophysics and structural biology. Here, we critically assess the use of empirical, solvent-accessible surface area-based calculations for the prediction of the binding of Src-SH2 domain with a series of tyrosyl phosphopeptides based on the high-affinity ligand from the hamster middle T antigen (hmT), where the residue in the pY+3 position has been changed. Two other peptides based on the C-terminal regulatory site of the Src protein and the platelet-derived growth factor receptor (PDGFR) are also investigated. Here, we take into account the effects of proton linkage on binding, and test five different surface area-based models that include different treatments for the contributions to conformational change and protein solvation. These differences relate to the treatment of conformational flexibility in the peptide ligand and the inclusion of proximal ordered solvent molecules in the surface area calculations. This allowed the calculation of a range of thermodynamic state functions (,Cp, ,S, ,H, and ,G) directly from structure. Comparison with the experimentally derived data shows little agreement for the interaction of SrcSH2 domain and the range of tyrosyl phosphopeptides. Furthermore, the adoption of the different models to treat conformational change and solvation has a dramatic effect on the calculated thermodynamic functions, making the predicted binding energies highly model dependent. While empirical, solvent-accessible surface area based calculations are becoming widely adopted to interpret thermodynamic data, this study highlights potential problems with application and interpretation of this type of approach. There is undoubtedly some agreement between predicted and experimentally determined thermodynamic parameters; however, the tolerance of this approach is not sufficient to make it ubiquitously applicable. [source] FPRL-1 induces modifications of migration-associated proteins in human neutrophilsPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 17 2006Karsten Boldt Abstract Human polymorphonuclear neutrophils (PMNs) are an important cell population of the innate immune system, which migrates following concentration gradients of chemokines or chemoattractants to locations of infection and inflammation in order to eliminate invading microorganisms and cell debris. For both migration and adhesion of PMNs to various tissues, the dynamic remodeling of the cytoskeleton is key prerequisite. In this context, the formyl peptide receptor-like,1 (FPRL-1) is an important chemoattractant receptor expressed on PMNs. In this study, we show that a short stimulation of FPRL-1 with either a synthetic peptide ligand (W-peptide) or a natural ligand (sCK,8-1) changes the protein pattern of PMNs as assessed by 2-D-DIGE. MS analysis of selected deregulated protein species resulted in the identification of proteins that are involved in the remodeling process of the actin- and tubulin-based cytoskeleton, such as L -plastin, moesin, cofilin, and stathmin. Subsequent validation experiments performed either by Western blotting or phosphoprotein-specific gel staining (Pro-Q Diamond) revealed that L -plastin is phosphorylated, whereas moesin, cofilin, and stathmin are dephosphorylated in PMNs upon FPRL-1 stimulation. These findings suggest that FPRL-1 signaling targets proteins that regulate the motility of PMNs and moreover show that 2-D-DIGE is a technique capable of detecting and quantifying differently modified (e.g., phosphorylated) protein variants. [source] Cell-Permeable ,-Peptide Inhibitors of p53/hDM2 ComplexationCHEMBIOCHEM, Issue 6 2009Elizabeth A. Harker Abstract Look at what the cat(ionic motif) dragged in! We report a general strategy to increase the cell permeability of ,3 -peptides. Introduction of a minimal cationic motif within the folded structure of a high-affinity ,3 -peptide ligand for hDM2 led to molecules with high 314 -helical structure, high hDM2 affinity and sufficient cell permeability to upregulate p53-dependent genes in live mammalian cells. Minimally cationic ,3 -peptides represent the critical first step towards a class of protease-resistant peptidomimetics that might modulate intracellular biological pathways. [source] Structure-Based Synthetic Mimicry of Discontinuous Protein Binding Sites: Inhibitors of the Interaction of Mena EVH1 Domain with Proline-Rich LigandsCHEMBIOCHEM, Issue 8 2006Cornelia Hunke Dr. Abstract The Mena EVH1 domain, a protein-interaction module involved in actin-based cell motility, recognizes proline-rich ligand motifs, which are also present in the sequence of the surface protein ActA of Listeria monocytogenes. The interaction of ActA with host Mena EVH1 enables the bacterium to actively recruit host actin in order to spread into neighboring cells. Based on the crystal structure of Mena EVH1 in complex with a polyproline peptide ligand, we have generated a range of assembled peptides presenting the Mena EVH1 fragments that make up its discontinuous binding site for proline-rich ligands. Some of these peptides were found to inhibit the interaction of Mena EVH1 with the ligand pGolemi. One of them was further characterized at the level of individual amino acid residues; this yielded information on the contribution of individual positions of the peptides to the interaction with the ligand and identified sites for future structure optimization. [source] A hexamer peptide ligand that binds selectively to staphylococcal enterotoxin B: isolation from a solid phase combinatorial libraryCHEMICAL BIOLOGY & DRUG DESIGN, Issue 2 2004G. Wang Abstract:, By screening a solid-phase combinatorial peptide library, a short peptide ligand, YYWLHH, has been discovered that binds with high affinity and selectivity to staphylococcal enterotoxin B (SEB), but only weakly to other SEs that share sequence and structural homology with SEB. Using column affinity chromatography with an immobilized YYWLHH stationary phase, it was possible to separate SEB quantitatively from Staphylococcus aureus fermentation broth, a complex mixture of proteins, carbohydrates and other biomolecules. The immobilized peptide was also used to purify native SEB from a mixture containing denatured and hydrolyzed SEB, and showed little cross-reactivity with other SEs. To our knowledge this is the first report of a highly specific short peptide ligand for SEB. Such a ligand is a potential candidate to replace antibodies for detection, removal and purification strategies for SEB. [source] A Gadolinium-Binding Cyclodecapeptide with a Large High-Field Relaxivity Involving Second-Sphere WaterCHEMISTRY - A EUROPEAN JOURNAL, Issue 29 2009Célia Abstract A new cyclodecapeptide incorporating two prolylglycine sequences as ,-turn inducers and bearing four side chains with acidic carboxyl groups for cation complexation has been prepared. Structural analysis in water by 1H,NMR spectroscopy and CD shows that this template adopts a conformation suitable for the complexation of lanthanide ions Ln3+, with its carboxyl groups oriented on the same face of the peptide scaffold. Luminescence titrations show that mononuclear Ln,PA complexes are formed with apparent stability constants of log,,110,6.5 (pH,7). The high-field water relaxivity values arising from the Gd,PA complex at 200,500,MHz have been interpreted with molecular parameters determined independently. The experimentally determined water relaxivities are undoubtedly 30,% higher than the expected values for this complex with two inner-sphere (IS) water molecules and a medium-range rotational correlation time (,R=386,ps (±10,%)). This led us to propose the existence of a large second-sphere (2S) contribution to the relaxivity caused by the interaction of water molecules with the hydrophilic peptide ligand by hydrogen-bonding. [source] Mechanism of modulation of T cell responses by N-palmitoylated peptidesEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 12 2004Clara Bueno Abstract Small structural changes in the antigenic peptides recognized by TCR can alter the biological properties of those peptides and convert them into weak agonists, partial agonists, or antagonists of these receptors. These altered peptide ligands (APL) are usually generated by conservative amino acid substitutions at TCR contact residues. Here, we show that APL with therapeutic properties can also be generated by attachment of palmitic acid at the N terminus of the peptide without the need to modify the peptide's primary sequence. Using N-palmitoylated pigeon cytochrome-c peptide 81,104 (PALPCC81,104), we were able to induce T cell hyporesponsiveness to the wild-type peptide in vitro. More importantly, administration of the PALPCC81,104 to mice reduced the responsiveness to the native peptide when tested ex vivo. Biochemical and functional experiments indicated that the action of N-palmitoylated peptides was due to the conversion of the native peptide into a weak agonist that could then induce T cell anergy. Our results demonstrate that N-palmitoylation of antigenic peptides is a feasible strategy to generate APL, as it avoids the need to screen multiple amino acid variants of each specific antigen to identify those with therapeutic properties. [source] An MHC anchor-substituted analog of myelin oligodendrocyte glycoprotein,35,55 induces IFN-, and autoantibodies in the absence of experimental autoimmune encephalomyelitis and optic neuritisEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 2 2004Mandy Abstract Previous strategies to ameliorate experimental autoimmune encephalitis (EAE) include the treatment of autoreactive T,cells with altered peptide ligands, which contain amino acid substitutions at TCR contact residues. We recently showed that a variant of myelin oligodendrocyte glycoprotein (MOG),35,55 possessing low affinity for MHC (45D) induced anergy in MOG,35,55-specific T,cells and reduced their encephalitogenicity upon adoptive transfer. Here we investigate the characteristics of the primary immune response to this MHC anchor-substituted peptide. Overall, we observed that immunization with 45D resulted in the production of IFN-, and anti-MOG,35,55 autoantibodies at levels similar to those of MOG,35,55-immunized mice with active EAE. However, no symptoms of clinical or histological EAE or overt histological optic neuritis were observed in 45D-immunized mice. Consistent with this finding, 45D-immunized mice did not exhibit CD4+ infiltrates into the CNS. Therefore, MOG,35,55-specific precursors stimulated with a weak ligand (45D) mediate some EAE-associated effector functions but are unable to fully initiate the inflammatory process in the central nervous system that leads to clinical manifestation of EAE. [source] Suboptimal engagement of the T-cell receptor by a variety of peptide,MHC ligands triggers T-cell anergyIMMUNOLOGY, Issue 1 2010Scheherazade Sadegh-Nasseri Summary T cells recognize antigen via the T-cell receptor (TCR) and produce a spectrum of responses that range from activation to anergy or cell death. The variety of outcomes may be dictated by the strength of the signals transmitted upon cognate recognition of the TCR. The physiological outcome of TCR engagement is determined by several factors, including the avidity of the ligand for TCR, the duration of engagement, and the presence and nature of accessory molecules present on antigen-presenting cells (APCs). In this review, we discuss a model of anergy induced by presentation of low densities of peptide,major histocompatibility complex (MHC) ligand in CD4+ T cells and compare it to anergy induced by altered peptide ligands in an effort to identify a unifying mechanism. We suggest that altered peptide ligand (APL) and low densities of agonist ligands induce anergy by engaging less than optimal numbers of TCRs. The physiological impacts of anergy in memory CD4+ T cells are discussed. [source] Transition metals as electron traps.JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 10 2009Abstract Transition metal cations Co2+, Ni2+ and Zn2+ form 1 : 1 : 1 ternary complexes with 2,2,-bipyridine (bpy) and peptides in aqueous methanol solutions that have been studied for tripeptides GGG and GGL. Electrospray ionization of these solutions produced singly charged [Metal(bpy)(peptide , H)]+ and doubly charged [Metal(bpy)(peptide)]2+ ions (Metal = metal ion) that underwent charge reduction by glancing collisions with Cs atoms at 50 and 100 keV collision energies. Electron transfer to [Metal(bpy)(peptide)]2+ ions was less than 4.2 eV exoergic and formed abundant fractions of non-dissociated charge-reduced intermediates. Charge-reduced [Metal(bpy)(peptide)]+ ions dissociated by the loss of a hydrogen atom, ammonia, water and ligands that depended on the metal ion. The Ni and Co complexes mainly dissociated by the elimination of ammonia, water, and the peptide ligand. The Zn complex dissociated by the elimination of ammonia and bpy. A sequence-specific fragment was observed only for the Co complex. Electron transfer to [Metal(bpy)(peptide , H)]+ was 0.6,1.6 eV exoergic and formed intermediate radicals that were detected as stable anions after a second electron transfer from Cs. [Metal(bpy)(peptide , H)] neutrals and their anions dissociated by the loss of bpy and peptide ligands with branching ratios that depended on the metal ion. Optimized structures for several spin states, electron transfer and dissociation energies were addressed by combined density functional theory and Møller,Plesset perturbational calculations to aid interpretation of experimental data. The experimentally observed ligand loss and backbone cleavage in charge-reduced [Metal(bpy)(peptide)]+ complexes correlated with the dissociation energies at the present level of theory. The ligand loss in +CR, spectra showed overlap of dissociations in charge-reduced [Metal(bpy)(peptide , H)] complexes and their anionic counterparts which complicated spectra interpretation and correlation with calculated dissociation energies. Copyright © 2009 John Wiley & Sons, Ltd. [source] Synthetic peptide vaccine development: measurement of polyclonal antibody affinity and cross-reactivity using a new peptide capture and release system for surface plasmon resonance spectroscopyJOURNAL OF MOLECULAR RECOGNITION, Issue 6 2004Paul J. Cachia Abstract A method has been developed for measurement of antibody affinity and cross-reactivity by surface plasmon resonance spectroscopy using the EK-coil heterodimeric coiled-coil peptide capture system. This system allows for reversible capture of synthetic peptide ligands on a biosensor chip surface, with the advantage that multiple antibody-antigen interactions can be analyzed using a single biosensor chip. This method has proven useful in the development of a synthetic peptide anti- Pseudomonas aeruginosa (PA) vaccine. Synthetic peptide ligands corresponding to the receptor binding domains of pilin from four strains of PA were conjugated to the E-coil strand of the heterodimeric coiled-coil domain and individually captured on the biosensor chip through dimerization with the immobilized K-coil strand. Polyclonal rabbit IgG raised against pilin epitopes was injected over the sensor chip surface for kinetic analysis of the antigen-antibody interaction. The kinetic rate constants, k(on) and k(off), and equilibrium association and dissociation constants, KA and KD, were calculated. Antibody affinities ranged from 1.14,×,10,9 to 1.60,×,10,5,M. The results suggest that the carrier protein and adjuvant used during immunization make a dramatic difference in antibody affinity and cross-reactivity. Antibodies raised against the PA strain K pilin epitope conjugated to keyhole limpet haemocyanin using Freund's adjuvant system were more broadly cross-reactive than antibodies raised against the same epitope conjugated to tetanus toxoid using Adjuvax adjuvant. The method described here is useful for detailed characterization of the interaction of polyclonal antibodies with a panel of synthetic peptide ligands with the objective of obtaining high affinity and cross-reactive antibodies in vaccine development. Copyright © 2004 John Wiley & Sons, Ltd. [source] Opioids in neuropathic painJOURNAL OF NEUROCHEMISTRY, Issue 2003R. Przew Neuropathic pain in human appears not to be opioid-resistant but only reduced sensitivity to systemic opioids is observed in this condition. We studied the contribution of central and peripheral mu-opioid receptors to the antinociception in rats with a spinal nerve ligation-induced neuropathy. Results of the present study indicate that both spinal and peripheral opioid receptors may contribute to the opioid-induced antinociception in the neuropathy. Further, mu-opioid peptide ligands (DAMGO and endomorphins) are more effective than opioid alkaloids in relieving of neuropathic pain. Moreover, reduction of the mu-opioid antinociceptive potency appears to be due to the fact that nerve injury reduced expression of mu-opioid receptors in the spinal ganglia. Identification of the molecular mechanisms involved may be of importance to the understanding of the molecular mechanism of opioid action in neuropathic pain, as well as to the development of better and more effective treatment of neuropathic pain in humans. [source] Cell adhesion molecules for targeted drug deliveryJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 9 2006Alison L. Dunehoo Abstract Rapid advancement of the understanding of the structure and function of cell adhesion molecules (i.e., integrins, cadherins) has impacted the design and development of drugs (i.e., peptide, proteins) with the potential to treat cancer and heart and autoimmune diseases. For example, RGD peptides/peptidomimetics have been marketed as anti-thrombic agents and are being investigated for inhibiting tumor angiogenesis. Other cell adhesion peptides derived from ICAM-1 and LFA-1 sequences were found to block T-cell adhesion to vascular endothelial cells and epithelial cells; these peptides are being investigated for treating autoimmune diseases. Recent findings suggest that cell adhesion receptors such as integrins can internalize their peptide ligands into the intracellular space. Thus, many cell adhesion peptides (i.e., RGD peptide) were used to target drugs, particles, and diagnostic agents to a specific cell that has increased expression of cell adhesion receptors. This review is focused on the utilization of cell adhesion peptides and receptors in specific targeted drug delivery, diagnostics, and tissue engineering. In the future, more information on the mechanism of internalization and intracellular trafficking of cell adhesion molecules will be exploited for delivering drug molecules to a specific type of cell or for diagnosis of cancer and heart and autoimmune diseases. © 2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 95: 1856,1872, 2006 [source] X-ray crystallographic studies on fibrinogen and fibrinJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 7 2003R. F. Doolittle Summary., More than a dozen crystal structures of fibrinogen and fibrin fragments have been reported, including a structure of a native fibrinogen. The majority of the other structures are fragments D and d -dimer crystallized in the presence or absence of synthetic peptide ligands patterned on the A and B ,knobs'. Overall, fibrinogens or their fragments from four different species , human, bovine, chicken and lamprey , have been studied so far, with only minor differences in the structures being observed. Although these studies have thrown much light on the details of the fibrinogen to fibrin conversion, much remains to be found out. [source] Melanocortin ligands: 30 years of structure,activity relationship (SAR) studiesMEDICINAL RESEARCH REVIEWS, Issue 3 2004Jerry Ryan Holder Abstract The challenge of peptide and peptidomimetic research is the development of methods and techniques to improve the biological properties of native peptides and to convert peptide ligands into non-peptide compounds. Improved biological properties of peptides includes enhancement of stability, potency, and receptor selectivity, for both in vivo and in vitro applications. The design of a ligand with specific activity and desired biological properties is a complex task, and, to accomplish this objective, knowledge about putative interactions between a ligand and the corresponding receptor will be valuable. This includes interactions for both the binding and signal transduction processes. Structure,activity relationship (SAR) studies involve systematic modification of a lead peptide and are designed to provide insight into potential interactions involved in the formation of the ligand,receptor complex. It is desirable to have knowledge about both favorable and unfavorable processes that may occur in putative ligand,receptor interactions that result in either receptor stimulation or inhibition. Herein, we discuss various SAR studies that have involved melanocortin peptides over three decades and the information these studies have provided to the melanocortin field. © 2004 Wiley Periodicals, Inc. Med Res Rev, 24, No. 3, 325,356, 2004 [source] Mimicry of dimerization by synthetic peptides designed to target homologous regions of proteinsPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 3 2003Donard S. Dwyer Abstract Rapid progress in sequencing various genomes has highlighted the need for the development of biochemical reagents for the detection of thousands of expressed gene products. The magnitude of this detection problem exceeds current technical capabilities. In an attempt to address this shortcoming, a novel approach has been developed called mimicry of dimerization. Peptide tags have been designed to bind to a specific region of parvalbumin on the basis of amino acid sequence homology with this segment. Multivalent ligands were produced by coupling the synthetic peptides to activated dextran polymers and binding was assessed by chemiluminescence of enhanced avidity reactions using a high density of target protein at the binding surface. Binding of the peptide ligands to parvalbumin was strongest under assay conditions that enriched for native monomeric protein and was affected by pH, temperature and solvent conditions. The results suggest that it should be possible to develop specific reagents for tagging proteins on the basis of sequence and secondary structure information. [source] Influence of peptide ligand surface density and ethylene oxide spacer arm on the capture of porcine parvovirusBIOTECHNOLOGY PROGRESS, Issue 5 2009Caryn L. Heldt Abstract In previous work, we identified two trimeric peptide ligands (designated WRW and KYY), which bound specifically to porcine parvovirus (PPV) and demonstrated their ability to capture and remove the virus from solutions containing 7.5% human blood plasma. This article examines the influences of peptide density and the presence of an ethylene oxide spacer arm on the efficiency of virus capture using these two ligands. The WRW peptide bound the most virus from plasma solutions at the lowest peptide density tested (0.008 mmol/g dry resin), and binding was enhanced by the presence of the spacer arm. On the other hand, the KYY peptide bound the most viruses at the same low peptide density, but it performed better in the absence of the spacer arm. Of the two, the binding efficiency of the WRW peptide was more sensitive to peptide density and spacer arm presence. These results indicate that low peptide densities enhance binding selectivity, facilitating specific peptide-virus binding even in the presence of plasma proteins which can theoretically bind nonspecifically. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] | ||||||||||||||||||||||||||||