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Recombinant Polypeptide (recombinant + polypeptide)
Selected AbstractsFunction-modulating human monoclonal antibodies against platelet-membrane receptors isolated from a phage-display libraryJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 8 2003Y. Hagay Summary., Monoclonal antibodies to platelet membrane receptors have been used extensively for analysis of receptor structure and function. Function-blocking human antibodies are being used for the development of antiplatelet drugs. We isolated human monoclonal antibodies from a library of single-chain Fv (scFv) antibodies displayed on the surface of filamentous phage, by selection on whole platelets. Eight different platelet-binding clones were isolated, of which three bound to the platelet-membrane glycoprotein (GP) GPIb in an ELISA assay. Specific elution with a recombinant polypeptide of von Willebrand factor (VWF) spanning the GPIb, binding site, yielded the same three phage clones. Two of the three anti-GPIb clones could be purified as scFv monoclonal antibodies, and they competed with each other for binding to intact platelets, suggesting that they bind at or near the same site on GPIb. Their binding affinities differed, however, and the clone with higher affinity inhibited ristocetin-induced platelet aggregation. These data indicate that selection from a phage display library of human scFvs using whole platelets can be applied for the isolation of functional antiplatelet-GPIb antibodies useful for the development of new therapeutic and diagnostic strategies. [source] Carcinoembryonic antigen-related cell adhesion molecule (CEACAM)-binding recombinant polypeptide confers protection against infection by respiratory and urogenital pathogensMOLECULAR MICROBIOLOGY, Issue 5 2005Darryl J. Hill Summary The human-specific pathogens Neisseria meningitidis, N. gonorrhoea, Haemophilus influenzae and Moraxella catarrhalis share the property of targeting the carcinoembryonic antigen (CEA)-related cell adhesion molecules (CEACAMs) expressed on human epithelia. CEACAMs are signalling receptors implicated in cell adhesion and regulation of several physiological functions. Their targeting by pathogens can lead to tissue invasion. Although the CEACAM-binding ligands of the bacteria are structurally diverse, they target a common site on the receptor. We have generated a recombinant polypeptide that blocks the interactions of the mucosal pathogens with human epithelial cells and antibodies against it inhibit M. catarrhalis interactions with the receptor. As such, it is a potential antimicrobial agent to prevent infection via a strategy unlikely to promote bacterial resistance and a vaccine candidate against M. catarrhalis. In addition, it could serve more widely as a novel research tool and as a potential therapeutic agent in CEACAM-based physiological disorders. [source] Purification and characterisation of two ACC oxidases expressed differentially during leaf ontogeny in white cloverPHYSIOLOGIA PLANTARUM, Issue 1 2000Deming Gong Two isoforms of ACC oxidase (ACO) (EC 1.4.3), expressed differentially during leaf ontogeny in white clover (Trifolium repens L.), have been identified and purified to homogeneity. One isoform, designated MGI, was purified from mature green leaf tissue while the second isoform, designated SEII, was purified from senescent leaf tissue. The isolation and purification of these isoforms were achieved using a combination of hydrophobic interaction chromatography, anion exchange chromatography, chromatofocusing and gel filtration column chromatography. The Mr of both MGI and SEII was determined to be 37.5 kDa by gel filtration, and 37 kDa (MGI), 35 kDa (SEII) by SDS-PAGE, indicating that both isoforms are active as monomers. During purification, both isoforms were recognised by a polyclonal antibody directed against a recombinant polypeptide derived from a white clover ACO gene expressed in mature green leaf tissue, TR-ACO2. In addition to molecular mass, differences between the two isoforms were observed in terms of pH optima, isoelectric point (pI), Km for ACC, optimal requirements for the co-substrate ascorbate, and NaHCO3 and Fe2+ as co-factors. The identification of distinct ACC oxidases from the same tissue at different developmental stages shows that the now widely observed transcriptional regulation of the ACO gene family in higher plants is also expressed in terms of differential regulation of enzyme isoforms. [source] Microstructural and tensile properties of elastin-based polypeptides crosslinked with Genipin and pyrroloquinoline quinoneBIOPOLYMERS, Issue 3 2007S. Vieth Abstract Elastin is an elastomeric, self-assembling extracellular matrix protein with potential for use in biomaterials applications. Here, we compare the microstructural and tensile properties of the elastin-based recombinant polypeptide (EP) EP20-244 crosslinked with either genipin (GP) or pyrroloquinoline quinone (PQQ). Recombinant EP-based sheets were produced via coacervation and subsequent crosslinking. The micron-scale topography of the GP-crosslinked sheets examined with atomic force microscopy revealed the presence of extensive mottling compared with that of the PQQ-crosslinked sheets, which were comparatively smoother. Confocal microscopy showed that the subsurface porosity in the GP-crosslinked sheets was much more open. GP-crosslinked EP-based sheets exhibited significantly greater tensile strength (P , 0.05). Mechanistically, GP appears to yield a higher crosslink density than PQQ, likely due to its capacity to form short-range and long-range crosslinks. In conclusion, GP is able to strongly modulate the microstructural and mechanical properties of elastin-based polypeptide biomaterials forming membranes with mechanical properties similar to native insoluble elastin. © 2006 Wiley Periodicals, Inc. Biopolymers 85: 199,206, 2007. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Characterization of epitopes recognized by anti- Streptococcus mutans P1 monoclonal antibodiesFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 3 2007William P. McArthur Abstract Sequences contributing to epitopes recognized by a panel of monoclonal antibodies (mAbs) against the Streptococcus mutans surface protein P1 were delineated by Western blot and enzyme-linked immunosorbent assay using a battery of deletion constructs and recombinant polypeptides. mAbs that recognize complex discontinuous epitopes reconstituted by combining the alanine-rich and proline-rich repeat domains and varying degrees of flanking sequence were identified as well as mAbs that bound epitopes contained within contiguous segments of P1. Cross-reactivity with SspA and SspB from Streptococcus gordonii is also reported. This information enables insight into the structure and function of a streptococcal adhesin and its correlates of protection and furthers our understanding of the immunomodulatory and bacterial-adherence inhibition activities of anti-P1 mAbs. [source] Efficient Synthesis of Protein-Drug Conjugates Using a Functionalizable Recombinant Elastin-Mimetic PolypeptideMACROMOLECULAR BIOSCIENCE, Issue 11 2006Doris Kaufmann Abstract Summary: This report describes the efficient conjugation of doxorubicin-glycine-phenylalanine-leucine-glycine (1a) and rhodamine-glycine-phenylalanine-leucine-glycine (1b) units to a monodisperse elastin-mimetic polypeptide (EMM)7 bearing eight primary amine groups for chemical attachment. The synthetic approach is based on the solid-phase synthesis of 1a and 1b followed by chemical conjugation to the elastin-mimetic polypeptide in the presence of HOBt/PyBob as activating agents to form the polypeptide conjugates 2a and 2b. Conjugation efficiency was 61.2% (4.9 doxorubicin units per polypeptide chain) for 2a and 53.7% (4.3 rhodamine units per polypeptide chain) for 2b, demonstrating the feasibility of using these tailor-made, recombinant polypeptides as potential drug carriers for cancer therapy. Schematic structure of the elastin-mimetic polypeptide (EMM)7. [source] Recombinant human elastin polypeptides self-assemble into biomaterials with elastin-like propertiesBIOPOLYMERS, Issue 4 2003Catherine M. Bellingham Abstract Processes involving self-assembly of monomeric units into organized polymeric arrays are currently the subject of much attention, particularly in the areas of nanotechnology and biomaterials. One biological example of a protein polymer with potential for self-organization is elastin. Elastin is the extracellular matrix protein that imparts the properties of extensibility and elastic recoil to large arteries, lung parenchyma, and other tissues. Tropoelastin, the ,70 kDa soluble monomeric form of elastin, is highly nonpolar in character, consisting essentially of 34 alternating hydrophobic and crosslinking domains. Crosslinking domains contain the lysine residues destined to form the covalent intermolecular crosslinks that stabilize the polymer. We and others have suggested that the hydrophobic domains are sites of interactions that contribute to juxtaposition of lysine residues in preparation for crosslink formation. Here, using recombinant polypeptides based on sequences in human elastin, we demonstrate that as few as three hydrophobic domains flanking two crosslinking domains are sufficient to support a self-assembly process that aligns lysines for zero-length crosslinking, resulting in formation of the crosslinks of native elastin. This process allows fabrication of a polymeric matrix with solubility and mechanical properties similar to those of native elastin. © 2003 Wiley Periodicals, Inc. Biopolymers 70: 445,455, 2003 [source] Analysis of the autoimmune epitopes on human testicular NASP using recombinant and synthetic peptidesCLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 2 2000I. N. Batova The human nuclear autoantigenic sperm protein, NASP, is a testicular histone-binding protein of 787 amino acids to which most vasectomized men develop autoantibodies. In this study to define the boundaries of antigenic regions and epitope recognition pattern, recombinant deletion mutants spanning the entire protein coding sequence and a human NASP cDNA sublibrary were screened with vasectomy patients' sera. Employing panel sera from 21 vasectomy patients with anti-sperm antibodies, a heterogeneous pattern of autoantibody binding to the recombinant polypeptides was detected in ELISA and immunoblotting. The majority of sera (20/21) had antibodies to one or more of the NASP fusion proteins. Antigenic sites preferentially recognized by the individual patients' sera were located within aa 32,352 and aa 572,787. Using a patient's serum selected for its reactivity to the whole recombinant protein in Western blots, cDNA clones positive for the C-terminal domain of the molecule were identified. The number and location of linear epitopes in this region were determined by synthetic peptide mapping and inhibition studies. The epitope-containing segment was delimited to the sequence aa 619,692 and analysis of a series of 74 concurrent overlapping 9mer synthetic peptides encompassing this region revealed four linear epitopes: amino acid residues IREKIEDAK (aa 648,656), KESQRSGNV (aa 656,664), AELALKATL (aa 665,673) and GFTPGGGGS (aa 680,688). All individual patients' sera reacted with epitopes within the sequence IRE,.GGS (aa 648,688). The strongest reactivity was displayed by peptides corresponding to the sequence AELALKATL (aa 665,673). Thus, multiple continuous autoimmune epitopes in NASP involving sequences in the conserved C-terminal domain as well as in the less conserved testis-specific N-terminal region comprising the histone-binding sites, as predicted for an antigen-driven immune response, may be a target of autoantibodies in vasectomized men and may provide a relevant laboratory variable to describe more accurately the spectrum of autoantibody specificities associated with the clinical manifestation of vasectomy. [source] | |||||||||||||