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Artykuły w czasopismach na temat "Β Peptide"
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Raymond, Danielle M., i Bradley L. Nilsson. "Multicomponent peptide assemblies". Chemical Society Reviews 47, nr 10 (2018): 3659–720. http://dx.doi.org/10.1039/c8cs00115d.
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This review presents recent efforts in the development of multicomponent supramolecular peptide assemblies with a focus on multicomponent assemblies derived from β-sheet peptides, low molecular weight peptides, peptide amphiphiles, coiled coil peptides, collagen, and related systems.
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Lupaescu, Ancuta-Veronica, Ionel Humelnicu, Brindusa Alina Petre, Catalina-Ionica Ciobanu i Gabi Drochioiu. "Direct evidence for binding of aluminum to NAP anti-amyloid peptide and its analogs". European Journal of Mass Spectrometry 26, nr 2 (24.09.2019): 106–16. http://dx.doi.org/10.1177/1469066719877714.
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NAP (NAPVSIPQ) is a small peptide derived from the activity-dependent neuroprotective protein (ADNP), which provides neuroprotection against amyloid-β peptide toxicity associated with Alzheimer disease. Several metal ions are able to promote the formation of amyloid-β peptide oligomers and protofibrils in human brain tissue. Although the relationship between metal ions and amyloid-β peptide peptides is extensively investigated, that with the NAP peptide is less understood. Nevertheless, our previous research revealed unexpected iron binding to NAP peptide and its analogs. However, a link between aluminum ions, Alzheimer disease and amyloid-β peptide or NAP peptides still remains controversial. Therefore, we have investigated the possible binding of aluminum ions to NAP peptide and its four analogs. Indeed, MALDI-ToF mass spectrometry (MS), including MS/MS study, and Fourier transform infrared (FT-IR) spectroscopy revealed an unexpected pattern of aluminum ion binding to both NAP peptide and its analogs. Our results have been discussed with respect to NAP protection against Alzheimer disease-related neurotoxicity.
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Tsutsumi, Hiroshi, Kazuhiko Nakano i Hisakazu Mihara. "Dihydrofolate reductase inhibitory peptides screened from a structured designed β-loop peptide library displayed on phage". Molecular BioSystems 11, nr 10 (2015): 2713–16. http://dx.doi.org/10.1039/c5mb00316d.
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Checco, James W., Dale F. Kreitler, Nicole C. Thomas, David G. Belair, Nicholas J. Rettko, William L. Murphy, Katrina T. Forest i Samuel H. Gellman. "Targeting diverse protein–protein interaction interfaces with α/β-peptides derived from the Z-domain scaffold". Proceedings of the National Academy of Sciences 112, nr 15 (30.03.2015): 4552–57. http://dx.doi.org/10.1073/pnas.1420380112.
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Peptide-based agents derived from well-defined scaffolds offer an alternative to antibodies for selective and high-affinity recognition of large and topologically complex protein surfaces. Here, we describe a strategy for designing oligomers containing both α- and β-amino acid residues (“α/β-peptides”) that mimic several peptides derived from the three-helix bundle “Z-domain” scaffold. We show that α/β-peptides derived from a Z-domain peptide targeting vascular endothelial growth factor (VEGF) can structurally and functionally mimic the binding surface of the parent peptide while exhibiting significantly decreased susceptibility to proteolysis. The tightest VEGF-binding α/β-peptide inhibits the VEGF165-induced proliferation of human umbilical vein endothelial cells. We demonstrate the versatility of this strategy by showing how principles underlying VEGF signaling inhibitors can be rapidly extended to produce Z-domain–mimetic α/β-peptides that bind to two other protein partners, IgG and tumor necrosis factor-α. Because well-established selection techniques can identify high-affinity Z-domain derivatives from large DNA-encoded libraries, our findings should enable the design of biostable α/β-peptides that bind tightly and specifically to diverse targets of biomedical interest. Such reagents would be useful for diagnostic and therapeutic applications.
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Oppegård, Camilla, Gunnar Fimland, Lisbeth Thorbæk i Jon Nissen-Meyer. "Analysis of the Two-Peptide Bacteriocins Lactococcin G and Enterocin 1071 by Site-Directed Mutagenesis". Applied and Environmental Microbiology 73, nr 9 (2.03.2007): 2931–38. http://dx.doi.org/10.1128/aem.02718-06.
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ABSTRACT The two peptides (Lcn-α and Lcn-β) of the two-peptide bacteriocin lactococcin G (Lcn) were changed by stepwise site-directed mutagenesis into the corresponding peptides (Ent-α and Ent-β) of the two-peptide bacteriocin enterocin 1071 (Ent), and the potencies and specificities of the various hybrid constructs were determined. Both Lcn and, to a lesser extent, Ent were active against all the tested lactococcal strains, but only Ent was active against the tested enterococcal strains. The two bacteriocins thus differed in their relative potencies to various target cells, despite their sequence similarities. The hybrid combination Lcn-α+Ent-β had low potency against all strains tested, indicating that these two peptides do not interact optimally. The reciprocal hybrid combination (i.e., Ent-α+Lcn-β), in contrast, was highly potent, indicating that these two peptides may form a functional antimicrobial unit. In fact, this hybrid combination (Ent-α+Lcn-β) was more potent against lactococcal strains than wild-type Ent was (i.e., Ent-α+Ent-β), but it was inactive against enterococcal strains (in contrast to Ent but similar to Lcn). The observation that Ent-α is more active against lactococci in combination with Lcn-β and more active against enterococci in combination with Ent-β suggests that the β peptide is an important determinant of target cell specificity. Especially the N-terminal residues of the β peptide seem to be important for specificity, since Ent-α combined with an Ent-β variant with Ent-to-Lcn mutations at positions 1 to 4, 7, 9, and 10 was >150-fold less active against enterococcal strains but one to four times more active against lactococcal strains than Ent-α+Ent-β. Moreover, Ent-to-Lcn single-residue mutations in the region spanning residues 1 to 7 in Ent-β had a more detrimental effect on the activity against enterococci than on that against lactococcal strains. Of the single-residue mutations made in the N-terminal region of the α peptide, the Ent-to-Lcn mutations N8Q and P12R in Ent-α influenced specificity, as follows: the N8Q mutation had no effect on activity against tested enterococcal strains but increased the activity 2- to 4-fold against the tested lactococcal strains, and the P12R mutation reduced the activity >150-fold and only ∼2-fold against enterococcal and lactococcal strains, respectively. Changing residues in the C-terminal half/part of the Lcn peptides (residues 20 to 39 and 25 to 35 in Lcn-α and Lcn-β, respectively) to those found in the corresponding Ent peptides did not have a marked effect on the activity, but there was an ∼10-fold or greater reduction in the activity upon also introducing Lcn-to-Ent mutations in the mid-region (residues 8 to 19 and 9 to 24 in Lcn-α and Lcn-β, respectively). Interestingly, the Lcn-to-Ent F19L+G20A mutation in an Lcn-Ent-β hybrid peptide was more detrimental when the altered peptide was combined with Lcn-α (>10-fold reduction) than when it was combined with Ent-α (∼2-fold reduction), suggesting that residues 19 and 20 (which are part of a GXXXG motif) in the β peptide may be involved in a specific interaction with the cognate α peptide. It is also noteworthy that the K2P and A7P mutations in Lcn-β reduced the activity only ∼2-fold, suggesting that the first seven residues in the β peptides do not form an α-helix.
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Schenk, Dale B., Peter Seubert, Ivan Lieberburg i Jan Wallace. "β-Peptide Immunization". Archives of Neurology 57, nr 7 (1.07.2000): 934. http://dx.doi.org/10.1001/archneur.57.7.934.
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Fujii, Daisuke, Kento Takase, Ami Takagi, Kei Kamino i Yoshiaki Hirano. "Design of RGDS Peptide-Immobilized Self-Assembling β-Strand Peptide from Barnacle Protein". International Journal of Molecular Sciences 22, nr 3 (27.01.2021): 1240. http://dx.doi.org/10.3390/ijms22031240.
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We designed three types of RGD-containing barnacle adhesive proteins using self-assembling peptides. In the present study, three types of RGD-containing peptides were synthesized by solid-phase peptide synthesis, and the secondary structures of these peptides were analyzed by CD and FT-IR spectroscopy. The mechanical properties of peptide hydrogels were characterized by a rheometer. We discuss the correlation between the peptide conformation, and cell attachment and cell spreading activity from the viewpoint of developing effective tissue engineering scaffolds. We created a peptide-coated cell culture substrate by coating peptides on a polystyrene plate. They significantly facilitated cell adhesion and spreading compared to a non-coated substrate. When the RGDS sequence was modified at N- or C-terminal of R-Y, it was found that the self-assembling ability was dependent on the strongly affects hydrogel formation and cell adhesion caused by its secondary structure.
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Plaisancié, Pascale, Rachel Boutrou, Monique Estienne, Gwénaële Henry, Julien Jardin, Armelle Paquet i Joëlle Léonil. "β-Casein(94-123)-derived peptides differently modulate production of mucins in intestinal goblet cells". Journal of Dairy Research 82, nr 1 (22.10.2014): 36–46. http://dx.doi.org/10.1017/s0022029914000533.
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We recently reported the identification of a peptide from yoghurts with promising potential for intestinal health: the sequence (94-123) of bovine β-casein. This peptide, composed of 30 amino acid residues, maintains intestinal homoeostasis through production of the secreted mucin MUC2 and of the transmembrane-associated mucin MUC4. Our study aimed to search for the minimal sequence responsible for the biological activity of β-CN(94-123) by using several strategies based on (i) known bioactive peptides encrypted in β-CN(94-123), (ii) in silico prediction of peptides reactivity and (iii) digestion of β-CN(94-123) by enzymes of intestinal brush border membranes. The revealed sequences were tested in vitro on human intestinal mucus-producing HT29-MTX cells. We demonstrated that β-CN(108-113) (an ACE-inhibitory peptide) and β-CN(114-119) (an opioid peptide named neocasomorphin-6) up-regulated MUC4 expression whereas levels of the secreted mucins MUC2 and MUC5AC remained unchanged. The digestion of β-CN(94-123) by intestinal enzymes showed that the peptides β-CN(94-108) and β-CN(117-123) were present throughout 1·5 to 3 h of digestion, respectively. These two peptides raised MUC5AC expression while β-CN(117-123) also induced a decrease in the level of MUC2 mRNA and protein. In addition, this inhibitory effect was reproduced in airway epithelial cells. In conclusion, β-CN(94-123) is a multifunctional molecule but only the sequence of 30 amino acids has a stimulating effect on the production of MUC2, a crucial factor of intestinal protection.
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Del Borgo, Mark P., Ketav Kulkarni i Marie-Isabel Aguilar. "Unique Functional Materials Derived from β-Amino Acid Oligomers". Australian Journal of Chemistry 70, nr 2 (2017): 126. http://dx.doi.org/10.1071/ch16511.
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The unique structures formed by β-amino acid oligomers, or β-peptide foldamers, have been studied for almost two decades, which has led to the discovery of several distinctive structures and bioactive molecules. Recently, this area of research has expanded from conventional peptide drug design to the formation of assemblies and nanomaterials by peptide self-assembly. The unique structures formed by β-peptides give rise to a set of new materials with altered properties that differ from conventional peptide-based materials; such new materials may be useful in several bio- and nanomaterial applications.
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Fox, Robert I., i Ho-Il Kang. "Mechanism of Action of Antimalarial Drugs: Inhibition of Antigen Processing and Presentation". Lupus 2, nr 1_suppl (luty 1993): 9–12. http://dx.doi.org/10.1177/0961203393002001031.
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Recent studies have elucidated the steps involved in the association of antigenic peptides with major histocompatibility complex (MHC) encoded proteins and have suggested how antimalarial compounds might influence this important site of immune activation. These steps of antigen presentation in the macrophage (or other antigen-presenting cells) include: (a) the partial proteolytic degradation of endogenous and exogenous proteins into peptides within the lysosome; (b) the synthesis of MHC class II (i.e. HLA-D associated) α, β, and invariant (Ii) chains in the endoplasmic reticulum; (c) the initial association of α-Ii and β-li chains in the endoplasmic reticulum and the transport of these complexes to the primary endosome; (d) the fusion of lysosomal vacuoles and endosomal vacuoles, allowing the mixtures of lysosomal enzymes, peptides, α–Ii and β–Ii; (e) the displacement of Ii chains by peptides to form α–β–peptide complexes in the endosome; and (f) the migration of α–β–peptide complexes to the macrophage cell surface where they can stimulate CD4 T cells, resulting in release of cytokines. A low pH is required for digestion of the protein by acidic hydrolases in the lysosome, for assembly of the α–β–peptide complex and for its transport to the cell surface. Chloroquine and hydroxychloroquine are weak diprotic bases that can diffuse across the cell membrane and raise the pH within cell vesicles. This background provides the underlying basis for the theory that antimalarials may act to prevent autoimmunity by the following putative mechanism. Antimalarial compounds may: (a) stabilize the α-Ii and β-Ii interactions and prevent low-affinity peptides from forming α–β–peptide complexes; and (b) interfere with the efficient movement of α-Ii, β-Ii and α–β–peptide complexes to the correct locations within the cell cytoplasm or to the cell surfaces. Decreased presentation of autoantigenic peptides by macrophages might then lead to downregulation of autoimmune CD4+ T cells and diminish release of cytokines associated with clinical and laboratory signs of autoimmune disease.
Rozprawy doktorskie na temat "Β Peptide"
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Das, Chittaranjan. "Designed β-Hairpin, β-Sheet And Mixed α-β Structures In Synthetic Peptides". Thesis, Indian Institute of Science, 2000. http://hdl.handle.net/2005/263.
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Synthetic construction of protein molecules has been widely pursued over the last two decades. A primary goal behind de novo protein design has been to build minimal systems by capturing the essential features of protein structures. Such minimal models can be used to understand underlying principles governing folding, structure, and function of proteins molecules. Several approaches envisioning successful construction of synthetic proteins have been described over the years, some of them being admirably successful (DeGrado et al, 1999; Richardson et al> 1992; Baltzer, 1998). Specific patterning of polar and apolar residues in synthetic sequences has been widely used to achieve designed polypeptide structures like helix bundles (DeGrado et ah, 1999) and (3-sheets (Smith and Regan, 1997; Lacroix et a/., 1998), with reliance on hydrophobic driving forces for folding. Our laboratory has been pursuing a distinctly alternative approach, that employs stereochemically constrained amino acids to generate specific secondary structures which can then be assembled into composite structures by appropriately chosen linking segments. This approach, which involves linking prefabricated modules of secondary structures can be termed as a "Meccano set" approach to protein design (Balaram, 1992). The studies embodied in the present thesis describe attempts at construction of synthetic polypeptide motifs using the stereochemically directing influence of conformationally constrained amino acid residues, such as DPro or Aib (α-aminoisobutyric acid). This thesis is subdivided into 8 chapters, with Chapter 1 providing a perspective of the field of protein design. Subsequent chapters (2-8) describe studies directed towards the specific goal of construction of polypeptide motifs.
Chapter 2 describes synthesis and conformational characterization of two octapeptides Boc-Leu-Val-Val-DPro-LAla-Leu-Val-Val-OMe (1) and Boc-Leu-Val-Val-DPro-DAla-Leu-Val-Val-OMe (2), designed to investigate the effect of specific β-turn stereochemistry on β-hairpin structures. 500 MHz NMR studies establish that both peptides 1 and 2 adopt predominantly β-hairpin conformations in chloroform and methanol solutions, with interstrand registry established by observation of long-range nuclear Overhauser effects (NOEs). Specific NOEs provide evidence for a type II' β-turn conformation for the DPro-LAla segment in 1, while the NMR data suggest that a type I' DPro-DAla β-turn conformation predominates in the peptide 2. The crystal structure of 1 reveals two independent molecules in the crystallographic asymmetric unit, both of which adopt β-hairpin conformations nucleated by a type II’ β-turn across DPro-LAla and stabilized by 3 cross strand hydrogen bonds. These designed β-hairpins with defined tight turns produce characteristic vibrational circular dichroism (VCD) patterns, demonstrating the utility of VCD as a probe for conformational analysis of β-hairpins.
In Chapter 3, we present conformational analysis on designed β-hairpin sequences incorporating a 'Phe-Phe' residue pair at a non-hydrogen bonding position. Two octapeptides Boc-Leu-Phe-Val-DPro-Gly-Leu-Phe-Val-OMe and Boc-Leu-Phe-Val-DPro-Ala-Leu-Phe-Val-OMe were synthesized and conformationally characterized by 500 MHz NMR spectroscopy. Specific NOEs observed in solution provide conclusive evidence favoring specific orientation effects pertaining to the 'Phe-Phe' pair. The peptides exhibited anomalous electronic CD, which has been explained in terms of aromatic contributions by the side chain chromophores. Interestingly, the VCD patterns obtained for these peptides were almost identical to those obtained for other β-hairpins, described in Chapter 2.
Chapter 4 describes the synthesis and conformational analysis of designed decapeptide sequences with centrally located DPro-Xxx β-trun segments. Two sequences Boc-Met-Leu»Phe-Val'DPro-Ala-Leu-Val-Val-Phe-OMe (1) and Boc-Met-Leu-Val-Val-^ro-Gly-Leu-Val-Val-Phe-OMe (2) were designed to study the effect of chain length elongation, of β-strands, on designed β-hairpin structures. 500 MHz NMR studies establish β-hairpin folds in both these sequences, with strand segments aligned even at the termini of the structures.
Multi-stranded, antiparallel β-sheet structures can be generated by successive placement of β-hairpin sequences in a single polypeptide chain. The successful construction of three stranded β-sheet structures is described in Chapter 5 of this dissertation. A 14-residue peptide Boc-Leu-Phe-Val-DPro-Gly-Leu-Val-Leu-Ala-DPro-Gly-Phe-Val-Leu-OMe (LFV14) was designed such that it is composed of three strand segments linked by two DPro-Gly turn segments. The peptide showed excellent solubility in apolar media, permitting detailed conformational analysis by 500 MHz NMR spectroscopy in organic solvents. Observation of long-range, interstrand NOEs, diagnostic of multiple hairpin structures, provides conclusive evidence for a predominantly populated three stranded β-sheet structure in solution. Extension of this strategy has been described in which an 18-residue peptide, Arg-Gly-Thr-Ile-Lys-DPro-Gly-Val-Thr-Phe-Ala-DPro-Ala-Thr-Lys-Tyr-Gly-Arg, was designed with enhanced solutility in water to probe (β-sheet structure formation in aqueous and mixed aqueous-methanol systems. NMR data provided conclusive evidence in favor of the desired structure being significantly populated in methanol and methanol-water mixtures (50 %, v/v). In water, spectroscopic evidence suggests that the long-range order expected of a three-stranded structure is lost, possibly due to water invading the interstrand hydrogen bonds.
Successful construction of a four-stranded antiparallel β-sheet structure has been
demonstrated in Chapter 6. A 26-residue peptide Arg-Gly-Thr-Ile-Lys»DPro-Gly-Ile-Thr-
Phe-Ala-DPro-Ala-Thr-Val-Leu-Phe-Ala-Val-DPro-Gly-Lys-Thr-Leu-Tyr-Arg was designed to have four strand segments linked by three DPro-Xxx turn segments. The peptide exhibited excellent NMR properties permitting structure determination by analysis of NOE data, which revealed that a four stranded β-sheet structure is indeed populated in methanol. Structural studies on this peptide in mixed methanol-water established that the four stranded β-sheet is appreciably populated at a composition of 50 % (v/v) methanol-water mixture, with the β-sheet structure still detectable even at a composition of 70 % water-30 % methanol. In a completely aqueous environment, the β-sheet structures is significantly disrupted, presumably due to solvent invasion. The nucleating β-turns, however, appear to have retained their structural integrity even in this competitive environment.
Chapter 7 describes the insertion of L-Lactic acid (Lac), a hydroxy acid, into polypeptide helices stabilized by a-aminoisobutyricacid (Aib). This study was undertaken to investigate the effect of hydrogen bond deletion on peptide helices. Crystal structure determination of three oligopeptides containing Lac residues has been performed. Peptide 1, Boc-Val-Ala-Leu-Aib-Val-Lac-Leu-Aib-Val-Ala-Leu-OMe, and peptide 2, Boc-Val-Ala-Leu-Aib-Val-Lac-Leu-Aib-Val-Leu-OMe adopt completely helical conformations in the crystalline state, with the Lac(6) residue comfortably accommodated in the center of a helix. NMR studies of peptide 1 and its all amide analog 4, Boc-Val-Ala-Leu-Aib-Val-Ala-Leu-Aib-Val-Ala-Leu-OMe, provide firm evidence for a continuous helical segment in both the cases. In a 14-residue peptide 3, Boc-Val-Ala-Leu-Aib- Val- Ala-Leu- Val- Ala-Leu- Aib-Val-Lac-Leu-OMe, residues Val( 1 )-Leu( 10) adopt a helical conformation, which is terminated by formation of a Schellman motif, with Aib(ll) as the site of chiral reversal. The loss of the hydrogen bond at the C-terminus appears to facilitate the chiral reversal at Aib(l 1).
In the final section of this thesis, Chapter 8, successful construction of a synthetic motif containing two distinct elements of secondary structure, a (β-hairpin and a helix, has been described. The design of a 17-residue peptide Boc-Val-Ala-Leu-Aib-Val-Ala-Leu-Gly-Gly-Leu-Phe-Val-DPro-Gly-Leu-Phe-Val-OMe, BH17, is based on a modular approach, in which previously characterized β-hairpin (Leu-Phe-Val-DPro-Gly-Leu-Phe-Val) and helix (Val-Ala-Leu-Aib-Val-Ala-Leu) modules are linked by a Gly-Gly linker. The positioning of the achiral Gly residue at position 8 facilitates termination of the potential helical segment (residues 1-7) by formation of a Schellman motif. Gly(9) is anticipated to be the sole conformationally flexible residue. NMR studies on BH17 indicated the presence of both the helix (residues 1-7) and the β-hairpin (residues 10-17) structures in the sequence, with four major conformational possibilities at the linking segment. Crystal structure determination of BH17 revealed that the two elements of structure are approximately arranged in an orthogonal fashion. The crystal structure validates the original premise that a modular assembly strategy may be viable for the construction of larger synthetic structures.
Chapter 9 summarises the major results of this thesis.
(For formulae, please refer "pdf" format)
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Chiricotto, Mara. "Hydrodynamic effect on β-amyloid peptide aggregation". Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC136/document.
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Un fait marquant et essentiel de la maladie neurodégénérative d’Alzheimer est la formation de plaques amyloïdes dans le cerveau, résultat de l’agrégation des protéines amyloïde-β (Aβ1-40/1-42). Le développement de nouveaux médicaments requiert la compréhension des mécanismes de formation des fibres amyloïdes et la connaissance de la structure et dynamique des oligomères métastables qui sont les vecteurs principaux de la neurotoxicité. Parce que les simulations atomistiques en solvant explicite ne peuvent pas être réalisées sur de grands systèmes pour des temps très longs, nous avons opté pour un modèle protéique gros grain (CG) avec un solvant implicite. Nous nous sommes intéressés dans ces travaux de thèse à clarifier le rôle d’interactions hydrodynamiques(HI) dans la dynamique de formation des agrégats du peptide Aβ(16-22), connu pour former également des fibres amyloïdes. Ces interactions sont essentielles pour modéliser,dans un solvant implicite, les processus se produisant dans des environnements cellulaires très encombrés. Notre approche est basée sur une méthode multi-échelle et multi-physique qui couple les techniques Lattice Boltzmann et de dynamique moléculaire(LBMD). Dans notre système, les interactions médiées par le solvant aqueux sont incluses naturellement. Pour le système moléculaire, nous avons choisi le modèle gros grain à haute résolution OPEP (Optimized Potential for Efficient Protein structure prediction). Pour la première fois, nous avons effectué des simulations quasi tout-atome pour de très grands systèmes contenant des milliers de peptides Aβ ( 16-22). Après avoir correctement réglé le paramètre clé de notre couplage afin d’obtenir la diffusivité expérimentale des monomères et des oligomères du peptide Aβ ( 16-22), nous avons démontré que les HI accélèrent le processus d’agrégation pour des systèmes de taille moyenne (100 Aβ (16-22) peptides) et grande (1000 Aβ (16-22) peptides). Une caractérisation détaillée de la taille des clusters et de l’organisation structurelle des peptides est présentée. Enfin,nous avons examiné comment la concentration affecte la première phase d’agrégation des peptides et leurs structuresThe self-assembly of misfolded amyloid-β (Aβ 1-40/1-42) proteins into insoluble fibrils is strongly linked to the pathogenesis of Alzheimer’s disease (AD). The development of new drugs requires the understanding of the mechanisms leading to fibril formation, and the knowledge of the dynamics and structures of the early metastable oligomers which are the main neurotoxic species. Because atomistic simulations in explicit solvent cannot be performed on very large systems for a significant time scale, we resort to a coarse grained (CG) protein model with an implicit solvent. Our investigation enlightens the role of hydrodynamic interactions (HI) in the kinetics of β-amyloidogenesis, interactions which are essential, when an implicit solvent is used, to model processes occurring in highly crowded like-cell environments, among others.Our approach is based on a multi-scale and multi-physics method that couples Lattice Boltzmann and Molecular Dynamics (LBMD) techniques. In our scheme the solvent- mediated interactions are included naturally. As a first step, we focus on Aβ (16-22) peptide, known to form amyloid fibril alone, and we adopt the high resolution CG OPEP (Optimized Potential for Efficient Protein structure prediction) model, developed in our laboratory. For the first time, we have performed quasi-all-atom simulations for very large systems containing thousands of Aβ (16-22) peptides. After the correct tuning of the key parameters of our coupling in order to obtain the experimental diffusivity of Aβ (16-22) monomer and small oligomers, we have demonstrated that HI speed up the aggregation process of medium (100 peptides) and large (1000 peptides) systems. A detailed characterization of the fluctuating clusters along the trajectories is presented in terms of their sizes and the structural organization of the peptides. Finally, we have investigated how changes in the concentration affect the early aggregation phase of the peptides and their structures
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Newby, Francisco Nicolas. "Structural studies of the Alzheimer's amyloid β peptide". Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607712.
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Liu, Yong-Peng. "Total Synthesis of Microsclerodermin D". Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASF024.
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La microsclerodermine D est un peptide macrocyclique d’origine marine qui comporte six amino acides, dont deux sont disponibles commercialement : la glycine (Gly) et la sarcosine (Sar). Les quatre autres amino acides : l’acide (R)-γ-amino-β-hydroxybutyrique (GABOB), le D-6-chlorotryptophane (6-Cl-Trp), un β-amino acide polyhydroxylé (APTO) et l’acide 3-amino-4-hydroxypyrrolidinoacetique (PyrrAA) seront préparés via de nouvelles voies de synthèse. Notre objectif est de développer une voie de synthèse de la microsclerodermine D modulable et qui permettrait la synthèse d’autres membres de la famille des microsclerodermines et d’analogues. Nos nous intéresserons également à de potentielles études permettant d’évaluer leurs propriétés biologiques et leur potentiel en tant qu’agent anticancéreuxMicrosclerodermin D is a macrocyclic peptide of marine origin which contains six amino acids, of which two are commercially available: glycine (Gly) and sarcosine (Sar). The four other amino acids: (R)-γ-amino-β-hydroxybutyric acid (GABOB), D-6-chlorotryptophan (6-Cl-Trp), a polyhydroxylated β-amino acid (APTO) and 3-amino-4-hydroxypyrrolidinoacetic acid (PyrrAA) will be accessible by new synthetic routes. Our goal is to develop a modular synthetic route to microsclerodermin D that could be applicable for the preparation of other microsclerodermin family members and analogues thereof. We are also looking forward to make some investigations on their biological activities or potential as anticancer drug
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Österlund, Nicklas. "Gas phase studies of the Amyloid-β peptide : Peptide oligomerization and interactions with membrane mimetics". Thesis, Stockholms universitet, Institutionen för biokemi och biofysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-155009.
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The amyloid-β peptide is an amphiphilic peptide that exhibits self-aggregating properties, forming the amyloid fibrils that can be found in the brains of Alzheimer patients. Today it is believed that it is the soluble Aβ oligomers rather than the mature fibrils that are the main neurotoxic species. These small peptide assemblies are known to associate with lipid membranes and form pores that can transport Ca2+ into the cell, which in part could be responsible for their neurotoxic properties. However, most biophysical methods that have been developed to study Aβ target either the monomer or the mature fibrils, and not the low abundance and polydisperse oligomers. In this work, a soft ionization mass spectrometry method that retains non-covalent oligomer interactions in the gas phase has been developed. Using this method, monomeric and oligomeric Aβ (1-40) from dimers up to octamers, except heptamers, were detected in vitro. It was also possible to detect and study the effects of peptide modifications such as methionine-35 oxidation. As mass spectrometry is a non-averaging technique the aggregation kinetics for reduced and oxidized peptides are followed simultaneously, and the results showed that the oxidized form of Aβ(1-40) aggregates slower and forms lower amounts of soluble oligomers than the reduced form. Additionally, Aβ(1-40) interactions with zwitterionic SB3-14 detergent micelles were studied in the gas phase, and it was demonstrated that Aβ-micelle complexes can survive in the mass spectrometer and be identified. Detergent head group charges seem to be essential for peptide-micelle interaction, both in the gas phase and in solution as no structure induction is observed upon addition of the non-ionic detergent DDM. Overall gas phase and solution properties agree well, which is encouraging for future gas phase studies of Aβ interactions with membrane mimetics.
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Klementieva, Oxana. "Influence of Cu(II) and Glycodendrimers on Amyloid-beta-Peptide Aggregation". Doctoral thesis, Universitat Internacional de Catalunya, 2012. http://hdl.handle.net/10803/78910.
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La malaltia d’Alzheimer es caracteritza per l’acumulació de plaques extracel.lulars amiloides, formades pels anomenats pèptids amiloides (Aβ40). L’homeòstasi del coure (Cu) es veu afectada en l’etiologia de la malaltia d’Alzheimer, encara que el seu rol és un fet controvertit.
Per a l’estudi de la influència del Cu(II) en l’agregació del pèptid amiloide, la morfologia i l’estructura secundària dels agregats amiloides formats en presència de Cu(II) s’han utilitzat AFM, TEM, SEM, SAXS, FTIR i espectrometria de fluorescència. A més, els efectes tòxics d’aquests agregats s’han estudiat en cèl.lules neuronals. Els resultats obtinguts mostren que aquests agregats són amorfos i presenten una toxicitat més alta que les fibres. Per a l’estudi dels dendrímers de maltosa com a possibles moduladors de l’agregació i de la toxicitat del pèptide amiloide. S’ha confirmat que aquests dendrimers no són tòxics en cèl.lules neuronals i que són capaços de modular l’agregació i toxicitat del pèptid amiloide. Aquests resultats permeten considerar als dendrimers de maltosa com a possibles eines per a reduir la toxicitat dels pèptids amilodies.Senile plaques of Alzheimer’s disease patients are composed primarily of the amyloid-β-peptide (Aβ). Recent studies implicate Cu(II) in the aetiology of AD. The role of Cu(II) in ADis currently highly disputed. Influence of Cu(II) on Aβ aggregation and amyloidogenic properties of glycodendrimers were investigated in this thesis. AFM, TEM, SEM, SAXS, FTIR and fluorescence spectroscopy were used to study a morphology and a secondary structure of Aβ-Cu(II) aggregates. The toxic effects of Aβ40-Cu(II) amorphous aggregates was confirmed for neuronal cell lines. It was shown that maltose glycodendrimers can be efficiently used to modulate Alzheimer’s amyloid peptide aggregation and inhibit cell toxicity by facilitating the clustering of amyloid fibrils. These results show that glycodendrimers are promising non-toxic agents in the search for anti-amyloidogenic compounds. It was also suggested that fibril clumping may be anti-amyloid toxicity strategy.
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Guivernau, Almazán Biuse 1988. "Modulation of Amyloid-β peptide aggregation and neurotoxicity in Alzheimer's disease". Doctoral thesis, Universitat Pompeu Fabra, 2016. http://hdl.handle.net/10803/585932.
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Aggregation of the amyloid-β (Aβ) peptide to form oligomers and amyloid fibrils is a central event in the pathogenesis of Alzheimer’s disease (AD). This thesis aims to provide a better understanding of Aβ toxicity and the impact of changes in Aβ aggregation, both relevant to AD. We have found that Aβ nitrotyrosination inhibits fibril formation, which favours the stabilization of small oligomers. We show that nitro-Aβ oligomers strongly bind to dendrites, altering N-methyl-D-aspartate receptor (NMDAR) physiological function and leading to neuronal dysfunction and cell death. Furthermore, we propose a model for Aβ fibril assembly, according to which fibril elongation is interrupted upon nitrotyrosination, due to the destabilization of interprotofibrillar contacts. Additionally, using a genome-wide screen in Saccharomyces cerevisiae, we have identified novel modulators of Aβ toxicity that are potential targets for the development of new AD therapeutic approaches.L’agregació del pèptid b-amiloide (Aβ) en forma d’oligòmers i fibres és un esdeveniment central en la patogènesi de la malaltia d’Alzheimer. Aquesta tesi pretén aprofundir en els coneixements actuals sobre la toxicitat causada per l’Aβ així com en l’impacte que tenen els canvis en l’agregació d’aquest, tots dos rellevants per la malaltia d’Alzheimer. Els nostres resultats indiquen que la nitrotirosinació de l’Aβ inhibeix la formació de fibres, afavorint l’estabilització d’oligòmers. Demostrem que els oligòmers d’Aβ nitrat s’uneixen a les dendrites, alterant la funció fisiològica dels receptors d’N-metil- D-aspartat (NMDAR) i provocant disfuncions neuronals i la mort cel·lular. A més, proposem un model d’assemblatge per a les fibres d’Aβ, segons el qual la nitrotirosinació interromp l’elongació de la fibra a causa de la desestabilització dels contactes entre protofibres. Addicionalment, utilitzant un cribratge genòmic en Saccharomyces cerevisiae, hem identificat nous moduladors de la toxicitat causada per Aβ, que podrien ser clau per al desenvolupament de noves estratègies terapèutiques de la malaltia Alzheimer.
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Lindberg, Hanna. "Engineering of Affibody molecules targeting the Alzheimer’s-related amyloid β peptide". Doctoral thesis, KTH, Proteinteknologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-173864.
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Moore, Claire E. J. "Investigation into glucagon like peptide-1 signalling in pancreatic β-cells". Thesis, University of Leicester, 2008. http://hdl.handle.net/2381/29965.
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Glucagon like peptide-1 (GLP-1) is a GS-coupled receptor agonist that exerts multiple effects on pancreatic beta-cells, including the stimulation of insulin gene expression and secretion, growth and survival. A number of kinases are activated in response to GLP-1R activation, including extracellular regulated kinases (Erk1/2), phosphatidylinositol 3-kinase (PI3K), protein kinase B (PKB) and mammalian target of rapamycin mTOR, all of which contribute in regulating various aspects of beta-cell function. However, the mechanism by which GLP-1 activates these signalling pathways in pancreatic beta-cells is not fully understood. Therefore, the objectives of this thesis were to investigate how GLP-1 signals to Erk1/2. PI3K/PKB and mTOR. It has previously been reported that GLP-1 stimulated Erk1/2 activation is dependent on the influx of Ca2+ specifically through L-Type VGCC. In this thesis I provide evidence that this increase in Ca2+ activates the Ca2+ dependent phosphatase, calcineurin which in turn activates IKK leading to the activation of the MEK kinase, Tp12. Ca2+ entry through L-Type VGCC also plays a key role in stimulating insulin secretion which I show is responsible for glucose stimulated PI3K activation and PKB phosphorylation. In contrast, GLP-1 can activate PI3K independent of insulin secretion which is unable to couple to PKB. Interestingly, GLP-1 is able to potentiate glucose stimulated mTOR activation via a PI3K leading to the phosphorylation of rpS6 on Ser240/244. Moreover, GLP-1 can stimulate the phosphorylation of rpS6 on Ser235/236 which is not dependent on mTOR activation or the two currently known S6Ks, S6K1/2 or p90RSK.
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Höger, Geralin. "Self-Organization of β-Peptide Nucleic Acid Helices for Membrane Scaffolding". Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2019. http://hdl.handle.net/21.11130/00-1735-0000-0003-C187-A.
Pełny tekst źródłaKsiążki na temat "Β Peptide"
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Haq, Mohammad Raies Ul. β-Casomorphins: A1 Milk, Milk Peptides and Human Health. Springer, 2020.
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Reuter, Bernhard. Generalisierte Markov-Modellierung: Modellierung irreversibler β-Amyloid-Peptid-Dynamik unter Mikrowelleneinfluss. Springer Spektrum, 2020.
Znajdź pełny tekst źródłaCzęści książek na temat "Β Peptide"
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Quigley, Elena, i Bradley L. Nilsson. "β-Sheet and β-Hairpin Peptide Nanomaterials". W Peptide Bionanomaterials, 53–86. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-29360-3_2.
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Hölzemann, Günter, i Michael Krug. "Analysis of β-turn mimetics". W Peptide Chemistry 1992, 512–14. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1474-5_149.
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Etienne, Marcus A., Nadia J. Edwin, Jed P. Aucoin, Paul S. Russo, Robin L. McCarley i Robert P. Hammer. "β-Amyloid Protein Aggregation". W Peptide Characterization and Application Protocols, 203–25. Totowa, NJ: Humana Press, 2007. http://dx.doi.org/10.1007/978-1-59745-430-8_7.
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Ono, Hideo, i Setsuo Harada. "Chapter 6. Discovery of new β-Lactam and β-Lactam like Antibiotics from Bacteria". W Biochemistry of Peptide Antibiotics, redaktorzy Horst Kleinkauf i Hans von Döhren, 131–58. Berlin, Boston: De Gruyter, 1990. http://dx.doi.org/10.1515/9783110886139-007.
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Inaba, Hiroshi, i Kazunori Matsuura. "Functional Peptide Nanocapsules Self-Assembled from β-Annulus Peptides". W Methods in Molecular Biology, 101–21. New York, NY: Springer US, 2020. http://dx.doi.org/10.1007/978-1-0716-0928-6_7.
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Okamoto, Yoshiko, Norio Nishi, Eiko Muta i Shoshi Ota. "Function mechanism of Formosan grey mullet protamine-mugiline β M6". W Peptide Chemistry 1992, 700–702. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1474-5_199.
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Shimohigashi, Yasuyuki, Hiroshi Matsumoto, Toshihide Iwata, Yukio Takano, Ryo Saito, Hiro-o. Kamiya i Motonori Ohno. "β-Amyloid fragment can be a specific ligand of substance P receptor". W Peptide Chemistry 1992, 366–68. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1474-5_106.
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Rossi, Filomena, Laura Zaccaro, Benedetto Di Blasio, Vincenzo Pavone, Ornella Maglio, Michele Saviano, Carlo Pedone i in. "β-Cyclodextrins as potent bioactive peptide delivery systems". W Peptides 1992, 577–78. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-1470-7_260.
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Liu, Enchi, i J. Michael Ryan. "Active Immunization Against the Amyloid-β Peptide". W Methods in Pharmacology and Toxicology, 19–35. New York, NY: Springer New York, 2016. http://dx.doi.org/10.1007/978-1-4939-3560-4_2.
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Gelman, Michael A., i Samuel H. Gellman. "Using Constrained β-Amino Acid Residues to Control β-Peptide Shape and Function". W Enantioselective Synthesis of β-Amino Acids, 527–91. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2005. http://dx.doi.org/10.1002/0471698482.ch22.
Pełny tekst źródłaStreszczenia konferencji na temat "Β Peptide"
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Lovas, Sándor, i Charles R. Watts. "Misfolding and Oligomerization of Amyloid β(1-40)". W The 24th American Peptide Symposium. Prompt Scientific Publishing, 2015. http://dx.doi.org/10.17952/24aps.2015.217.
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Lomakin, Aleksey, David B. Teplow, Daniel A. Kirschner i George B. Benedek. "Nucleation and Growth of Amyloid β-Protein Fibrils: Detection of Nuclei and Quantitation of Rate Constants". W Photon Correlation and Scattering. Washington, D.C.: Optica Publishing Group, 1996. http://dx.doi.org/10.1364/pcs.1996.sab.3.
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Alzheimer's disease is a progressive, neurodegenerative disorder characterized by amyloid deposition in senile plaques in the cerebral parenchyma and vasculature.(1) These plaques are composed primarily of fibers of the amyloid β-protein, Aβ. A number of studies have provided information on the structure of fibrils formed both in vivo and in vitro, and on factors affecting fiber formation. Synthetic Aβ peptides also form fibers which are ultrastructurally indistinguishable from those isolated from the brain. These peptides have been utilized to examine how a variety of parameters, including temperature, pH, solvent composition, peptide concentration, and peptide sequence, influence the final structure of Aβ aggregates. What is substantially less understood, however, is the kinetics of Aβ fibril growth.
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Kissoon, Nicola N., Andre´s D. Gutierrez, Anant K. Paravastu i Ongi Englander. "Preparation and Integration of Beta Amyloid Protein Nanofibers With Microfabricated Electrodes". W ASME 2010 International Mechanical Engineering Congress and Exposition. ASMEDC, 2010. http://dx.doi.org/10.1115/imece2010-38360.
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Micro and nano fabricated bio-systems and bio-devices can be produced once compatible processes for the integration of biomaterials and micro and nano systems are developed. Here, we demonstrate the integration of Alzheimer’s β-amyloid peptide nanofibers with metalized electrodes. The metalized electrodes and Alzheimer’s β-amyloid peptide nanofiber solutions are prepared separately. Metalized electrodes, composed of either chrome/gold or aluminum, with multiple electrodes are prepared using standard photolithography processes. Meanwhile, the Alzheimer’s β-amyloid peptide nanofiber solutions are prepared via the hydration of β-amyloid powder at various concentrations. The self-assembly of the β-amyloid nanofibers, to achieve well-dispersed networks, is optimized through periodic sonication and readdition of aliquots over timed intervals. The β-amyloid peptide solution can be successfully deposited onto the metalized electrodes to yield dense yet well-dispersed nanofiber arrays.
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Nilsson, Bradley L., Danielle M. Raymond i Jade J. Welch. "Rippled β-Sheet Fibrils from Coassembled Enantiomeric Amphipathic Peptides as Potential Microbicide Biomaterials". W The 24th American Peptide Symposium. Prompt Scientific Publishing, 2015. http://dx.doi.org/10.17952/24aps.2015.033.
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Lasota, Anika, Oliwia Fraczak, Adriana Muchowska, Aleksandra Misicka, Michal Nowakowski, Maciej Maciejczyk, Andrzej Ejchart i Aleksandra Olma. "Structure-Activity Relationships of Constrained Dermorphin Analogues Containing an α-Alkyl-β-Substituted Alanines". W The 24th American Peptide Symposium. Prompt Scientific Publishing, 2015. http://dx.doi.org/10.17952/24aps.2015.073.
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Manandhar, Bikash, William Silvers, Amit Kumar, Su-Tang Lo, Xiankai Sun i Jung-Mo Ahn. "Pancreatic β-Cell Imaging with High Affinity Peptide Ligands to the GLP-1 Receptor". W The 24th American Peptide Symposium. Prompt Scientific Publishing, 2015. http://dx.doi.org/10.17952/24aps.2015.154.
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Bacon-Baguley, Theresa, Suzanne Kendra-Franczak i Daniel Walz. "THROMBOSPONDIN SPECIFICALLY INTERACTS WITH AMINO ACID SEQUENCES WITHIN THE A α- AND B β- CHAINS OF FIBRINOGEN". W XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643822.
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Thrombospondin (TSP) is responsible for the secretion-dependent phase of platelet aggregation. The mechanism of this action is believed to be through the binding of TSP to fibrinogen, resulting in the stabilization of the platelet aggregate. It has been established that the binding of fibrinogen to the platelet surface is dependent upon peptide sequences present, respectively, in the Aa- and y-chains. We have hypothesized that the binding of TSP to fibrinogen is also dependent upon unique fibrinogen peptide sequences. To test this hypothesis we have examined the interaction of TSP and f.ih.r.inogen. using..a.-blat-b.inding assaLy of reduced fibrinogen, the separated fibrinogen chains, selected fibrinogen domains or peptides generated from cyanogen bromide cleaved chains. Iodinated TSP bound specifically to the Aα - and Bβ - chains. Binding to these chains was calcium independent, mutually exclusive and could be blocked either by preincubation of TSP with 9.4 μ M fibrinogen or by preincubation of fibrinogen with 1.1 nM thrombospondin. TSP bound to the D and DD plasmin fragment of fibrinogen; TSP interacted exclusively with the B-chain component of the DD fragment. The cyanogen bromide fragments of the separated Aα - and Bβ -chains were resolved through a combination of gel filtration and reverse-phase chromatography. TSP was found to bind to a single peptide within these fibrinogen chains. These studies demonstrate that thrombospondin interacts with at least two distinct sites on fibrinogen, and these sites differ from those already described for fibrinogen binding to platelets.
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Makwana, Kamlesh Madhusudan, i Radhakrishnan Mahalakshmi. "Structure Stabilizing Role of Aromatic Interactions is Decided by Spatial Arrangement of Aromatic Pairs: A Case Study with Designed Peptide β-Hairpins". W The 24th American Peptide Symposium. Prompt Scientific Publishing, 2015. http://dx.doi.org/10.17952/24aps.2015.220.
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Rotolo, Jim A., Erin Gallagher, Lila Ghamsari, Siok Leong, Ricardo Ramirez, Mark Koester, Gene Merutka i Barry J. Kappel. "Abstract 964: β-catenin antagonist peptide attenuates Wnt-dependent oncogenic activity". W Proceedings: AACR Annual Meeting 2021; April 10-15, 2021 and May 17-21, 2021; Philadelphia, PA. American Association for Cancer Research, 2021. http://dx.doi.org/10.1158/1538-7445.am2021-964.
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Ebo, Chinyere B., Carly Schmidgall, Christina Lipscombe, Harsh Patel, Qian Chen, Robert Barsotti i Lindon H. Young. "Myristoylated PKC β II Peptide Inhibitor Exerts Dose-Dependent Inhibition of N-Formyl-L-Methionyl-L-Leucyl-L-Phenylalanine (fMLP) Induced Leukocyte Superoxide Release". W The 24th American Peptide Symposium. Prompt Scientific Publishing, 2015. http://dx.doi.org/10.17952/24aps.2015.147.
Pełny tekst źródłaRaporty organizacyjne na temat "Β Peptide"
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Altstein, Miriam, i Ronald J. Nachman. Rational Design of Insect Control Agent Prototypes Based on Pyrokinin/PBAN Neuropeptide Antagonists. United States Department of Agriculture, sierpień 2013. http://dx.doi.org/10.32747/2013.7593398.bard.
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The general objective of this study was to develop rationally designed mimetic antagonists (and agonists) of the PK/PBAN Np class with enhanced bio-stability and bioavailability as prototypes for effective and environmentally friendly pest insect management agents. The PK/PBAN family is a multifunctional group of Nps that mediates key functions in insects (sex pheromone biosynthesis, cuticular melanization, myotropic activity, diapause and pupal development) and is, therefore, of high scientific and applied interest. The objectives of the current study were: (i) to identify an antagonist biophores (ii) to develop an arsenal of amphiphilic topically active PK/PBAN antagonists with an array of different time-release profiles based on the previously developed prototype analog; (iii) to develop rationally designed non-peptide SMLs based on the antagonist biophore determined in (i) and evaluate them in cloned receptor microplate binding assays and by pheromonotropic, melanotropic and pupariation in vivo assays. (iv) to clone PK/PBAN receptors (PK/PBAN-Rs) for further understanding of receptor-ligand interactions; (v) to develop microplate binding assays for screening the above SMLs. In the course of the granting period A series of amphiphilic PK/PBAN analogs based on a linear lead antagonist from the previous BARD grant was synthesized that incorporated a diverse array of hydrophobic groups (HR-Suc-A[dF]PRLa). Others were synthesized via the attachment of polyethylene glycol (PEG) polymers. A hydrophobic, biostablePK/PBAN/DH analog DH-2Abf-K prevented the onset of the protective state of diapause in H. zea pupae [EC50=7 pmol/larva] following injection into the preceding larval stage. It effectively induces the crop pest to commit a form of ‘ecological suicide’. Evaluation of a set of amphiphilic PK analogs with a diverse array of hydrophobic groups of the formula HR-Suc-FTPRLa led to the identification of analog T-63 (HR=Decyl) that increased the extent of diapause termination by a factor of 70% when applied topically to newly emerged pupae. Another biostablePK analog PK-Oic-1 featured anti-feedant and aphicidal properties that matched the potency of some commercial aphicides. Native PK showed no significant activity. The aphicidal effects were blocked by a new PEGylated PK antagonist analog PK-dF-PEG4, suggesting that the activity is mediated by a PK/PBAN receptor and therefore indicative of a novel and selective mode-of-action. Using a novel transPro mimetic motif (dihydroimidazole; ‘Jones’) developed in previous BARD-sponsored work, the first antagonist for the diapause hormone (DH), DH-Jo, was developed and shown to block over 50% of H. zea pupal diapause termination activity of native DH. This novel antagonist development strategy may be applicable to other invertebrate and vertebrate hormones that feature a transPro in the active core. The research identifies a critical component of the antagonist biophore for this PK/PBAN receptor subtype, i.e. a trans-oriented Pro. Additional work led to the molecular cloning and functional characterization of the DH receptor from H. zea, allowing for the discovery of three other DH antagonist analogs: Drosophila ETH, a β-AA analog, and a dF analog. The receptor experiments identified an agonist (DH-2Abf-dA) with a maximal response greater than native DH. ‘Deconvolution’ of a rationally-designed nonpeptide heterocyclic combinatorial library with a cyclic bis-guanidino (BG) scaffold led to discovery of several members that elicited activity in a pupariation acceleration assay, and one that also showed activity in an H. zea diapause termination assay, eliciting a maximal response of 90%. Molecular cloning and functional characterization of a CAP2b antidiuretic receptor from the kissing bug (R. prolixus) as well as the first CAP2b and PK receptors from a tick was also achieved. Notably, the PK/PBAN-like receptor from the cattle fever tick is unique among known PK/PBAN and CAP2b receptors in that it can interact with both ligand types, providing further evidence for an evolutionary relationship between these two NP families. In the course of the granting period we also managed to clone the PK/PBAN-R of H. peltigera, to express it and the S. littoralis-R Sf-9 cells and to evaluate their interaction with a variety of PK/PBAN ligands. In addition, three functional microplate assays in a HTS format have been developed: a cell-membrane competitive ligand binding assay; a Ca flux assay and a whole cell cAMP ELISA. The Ca flux assay has been used for receptor characterization due to its extremely high sensitivity. Computer homology studies were carried out to predict both receptor’s SAR and based on this analysis 8 mutants have been generated. The bioavailability of small linear antagonistic peptides has been evaluated and was found to be highly effective as sex pheromone biosynthesis inhibitors. The activity of 11 new amphiphilic analogs has also been evaluated. Unfortunately, due to a problem with the Heliothis moth colony we were unable to select those with pheromonotropic antagonistic activity and further check their bioavailability. Six peptides exhibited some melanotropic antagonistic activity but due to the low inhibitory effect the peptides were not further tested for bioavailability in S. littoralis larvae. Despite the fact that no new antagonistic peptides were discovered in the course of this granting period the results contribute to a better understanding of the interaction of the PK/PBAN family of Nps with their receptors, provided several HT assays for screening of libraries of various origin for presence of PK/PBAN-Ragonists and antagonists and provided important practical information for the further design of new, peptide-based insecticide prototypes aimed at the disruption of key neuroendocrine physiological functions in pest insects.
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Altstein, Miriam, i Ronald Nachman. Rationally designed insect neuropeptide agonists and antagonists: application for the characterization of the pyrokinin/Pban mechanisms of action in insects. United States Department of Agriculture, październik 2006. http://dx.doi.org/10.32747/2006.7587235.bard.
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The general objective of this BARD project focused on rationally designed insect neuropeptide (NP) agonists and antagonists, their application for the characterization of the mechanisms of action of the pyrokinin/PBAN (PK-PBAN) family and the development of biostable, bioavailable versions that can provide the basis for development of novel, environmentally-friendly pest insect control agents. The specific objectives of the study, as originally proposed, were to: (i) Test stimulatory potencies of rationally designed backbone cyclic (BBC) peptides on pheromonotropic, melanotropic, myotropic and pupariation activities; (ii) Test the inhibitory potencies of the BBC compounds on the above activities evoked either by synthetic peptides (PBAN, LPK, myotropin and pheromonotropin) or by the natural endogenous mechanism; (iii) Determine the bioavailability of the most potent BBC compounds that will be found in (ii); (iv) Design, synthesize and examine novel PK/PBAN analogs with enhanced bioavailability and receptor binding; (v) Design and synthesize ‘magic bullet’ analogs and examine their ability to selectively kill cells expressing the PK/PBAN receptor. To achieve these goals the agonistic and antagonistic activities/properties of rationally designed linear and BBC neuropeptide (NP) were thoroughly studied and the information obtained was further used for the design and synthesis of improved compounds toward the design of an insecticide prototype. The study revealed important information on the structure activity relationship (SAR) of agonistic/antagonistic peptides, including definitive identification of the orientation of the Pro residue as trans for agonist activity in 4 PK/PBANbioassays (pheromonotropic, pupariation, melanotropic, & hindgut contractile) and a PK-related CAP₂b bioassay (diuretic); indications that led to the identification of a novel scaffold to develop biostbiostable, bioavailable peptidomimetic PK/PBANagonists/antagonists. The work led to the development of an arsenal of PK/PBAN antagonists with a variety of selectivity profiles; whether between different PKbioassays, or within the same bioassay between different natural elicitors. Examples include selective and non-selective BBC and novel amphiphilic PK pheromonotropic and melanotropic antagonists some of which are capable of penetrating the moth cuticle in efficacious quantities. One of the latter analog group demonstrated unprecedented versatility in its ability to antagonize a broad spectrum of pheromonotropic elicitors. A novel, transPro mimetic motif was proposed & used to develop a strong, selective PK agonist of the melanotropic bioassay in moths. The first antagonist (pure) of PK-related CAP₂b diuresis in flies was developed using a cisPro mimetic motif; an indication that while a transPro orientation is associated with receptor agonism, a cisPro orientation is linked with an antagonist interaction. A novel, biostablePK analog, incorporating β-amino acids at key peptidase-susceptible sites, exhibited in vivo pheromonotropic activity that by far exceeded that of PBAN when applied topically. Direct analysis of neural tissue by state-of-the-art MALDI-TOF/TOF mass spectrometry was used to identify specific PK/PK-related peptides native to eight arthropod pest species [house (M. domestica), stable (S. calcitrans), horn (H. irritans) & flesh (N. bullata) flies; Southern cattle fever tick (B. microplus), European tick (I. ricinus), yellow fever mosquito (A. aegypti), & Southern Green Stink Bug (N. viridula)]; including the unprecedented identification of mass-identical Leu/Ile residues and the first identification of NPs from a tick or the CNS of Hemiptera. Evidence was obtained for the selection of Neb-PK-2 as the primary pupariation factor of the flesh fly (N. bullata) among native PK/PK-related candidates. The peptidomic techniques were also used to map the location of PK/PK-related NP in the nervous system of the model fly D. melanogaster. Knowledge of specific PK sequences can aid in the future design of species specific (or non-specific) NP agonists/antagonists. In addition, the study led to the first cloning of a PK/PBAN receptor from insect larvae (S. littoralis), providing the basis for SAR analysis for the future design of 2ⁿᵈgeneration selective and/or nonselective agonists/antagonists. Development of a microplate ligand binding assay using the PK/PBAN pheromone gland receptor was also carried out. The assay will enable screening, including high throughput, of various libraries (chemical, molecular & natural product) for the discovery of receptor specific agonists/antagonists. In summary, the body of work achieves several key milestones and brings us significantly closer to the development of novel, environmentally friendly pest insect management agents based on insect PK/PBANNPs capable of disrupting critical NP-regulated functions.