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Unusual supramolecular assembly and nonlinear optical properties of l-histidinium hydrogen malate

Gomes, E. de Matos; Rodrigues, V. H.; Costa, M. M. R.; Belsley, M. S.; Cardoso, P. J. M.; Gonçalves, C. F.; Proença, F.
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
ENG
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46.44%
A new nonlinear optical material, l-histidinium hydrogen malate, has been synthesized. The crystal structure was determined at 90 K by single-crystal X-ray diffraction in order to analyze its supramolecular structure. A new building block type has been found. The malate anions form head-to-side infinite chains parallel to [100], via O-H...O interactions, instead of the usual head-to-tail infinite chains found in other hydrogen malate salts. The l-histidine cations form chains parallel to [100] via N-H...O hydrogen bonds, with cations of adjacent chains in anti-parallel way. The compound shows a good optical second-harmonic generation capability with an effective second-order susceptibility estimated to be 0.70 of that for potassium dihydrogen phosphate.; http://www.sciencedirect.com/science/article/B6WM2-4JY4145-3/1/a3f1c7be73432d0bb15977e2639292c6

Two New Supramolecular Assemblies Obtained by Reaction Between Saccharin and Long-chain Diamines

CASTELLANO, Eduardo Ernesto; PIRO, Oscar E.; PARAJON-COSTA, Beatriz S.; BARAN, Enrique J.
Fonte: VERLAG Z NATURFORSCH Publicador: VERLAG Z NATURFORSCH
Tipo: Artigo de Revista Científica
ENG
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The crystal Structures of heptamethylenediammonium bis(saccharinate) monohydrate, [H(3)N-(CH(2))(7)-NH(3)](sac)(2)center dot H(2)O (1) 0 (1) and octamethylenediammonium bis(saccharinate) hemihydrate, [H(3)N-(CH(2))(8)-NH(3)](sac)(2)center dot 0.5H(2)O (2), were determined-by single-crystal X-ray diffraction methods. Compound I crystallizes in the triclinic space group P (1) over bar with 2 molecules per unit cell, and 2 in the monoclinic space group P2(1)/a with Z = 4. The saccharinate moiety is planar in both compounds presenting bonding characteristics comparable to those found in other saccharinate salts. The ionic crystals are further stabilized by an extensive H-bonding network, which links the anions and cations into an infinite three-dimensional Supramolecular assembly. The FTIR spectra of the adducts are briefly discussed in comparison with those of the constituent Molecules.; CONICET (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas de Argentina (CONICET); UNILP (Argentina); UNILP (Argentina); FAPESP (Brazil); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Arranjos supramoleculares de drogas em lípides sintéticos e/ ou polieletrólitos: estabidade coloidal e atividade in vitro; Supramolecular assemblies of drugs in synthetic lipid and/ or polyelectrolytes: colloid stability and in vitro activity

Vieira, Débora Braga
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 15/04/2008 PT
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46.87%
Formação, estabilidade coloidal e atividade in vitro contra Candida albicans dos arranjos supramoleculares compostos por drogas, lípides catiônicos e/ ou polieletrólitos foram sistematicamente avaliados através de espalhamento de luz dinâmico para tamanho de partículas, análise de potencial-zeta, espectrofotometria UV-visível, efeitos de droga sobre a transição de fase gel para líquido-cristalina da bicamada catiônica e quantificação de incorporação de droga nos diferentes sistemas. Arranjos supramoleculares de drogas antifúngicas como miconazol ou anfotericina B foram obtidos por solubilização das drogas em fragmentos de bicamada catiônica de brometo de dioctadecildimetilamônio ou como partículas de droga recobertas com uma camada do mesmo lípide catiônico. Como modelo de droga anticancerígena, a cisplatina foi incorporada com sucesso em polieletrólitos de carga oposta: quitosana e carboximetilcelulose. Cisplatina induziu substancial estabilização coloidal e redução de tamanho de partículas de carboximetilcelulose-quitosana, possivelmente atuando como agente de ligação cruzada entre os dois polieletrólitos. Assim também, arranjos supramoleculares de anfotericina B em baixa e em alta proporção molar droga: lípide catiônico foram revestidos com polieletrólitos como carboximetilcelulose...

Planejamento, obtenção e caracterização de novas formas sólidas do fármaco antirretroviral lamivudina (3TC); Design, production and characterization of new solid forms of antiretroviral drug lamivudine (3TC)

Clavijo, Juan Carlos Tenorio
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 22/07/2013 PT
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Este trabalho enquadra-se dentro dos objetivos da engenharia de cristais moleculares para a obtenção de novas formas sólidas que possam apresentar propriedades farmacêuticas aprimoradas, especificamente de um dos fármacos mais utilizados e comercializados na terapia antirretroviral, contra o HIV: lamivudina, β-L-2',3'-didesoxi-3'-tiocitidina (3TC). As formas cristalinas apresentadas correspondem aos sais dos ácidos inorgânicos: bromidrato (3TCH+-Br-), difluoridrato de hidrogênio (3TCH+-F-HF) e nitrato de lamivudina (3TCH+-NO3-). Estes novos sais cristalizaram no grupo espacial não-centrossimétrico P21, com um par iônico por unidade assimétrica. Os sais halogenados (3TCH+-Br- e 3TCH+-F-HF) apresentaram arranjos supramoleculares isoestruturais inclusive com o sal anidro do cloridrato de lamivudina (3TCH+-Cl-), reportado em trabalhos anteriores no nosso grupo de pesquisa, e cuja solubilidade no equilíbrio apresentou um aumento em relação à forma farmacêutica da 3TC. A característica principal dos arranjos cristalinos destes sais está relacionada com o ordenamento supramolecular das unidades catiônicas 3TCH+, a qual é constante, observando-se a formação de vacâncias entre elas ao longo do eixo cristalino a...

Supercomplexes of Prokaryotic Aerobic Respiratory Chains-Escherichia coli and Bacillus subtilis supramolecular assemblies

Sousa, Pedro Miguel Ferreira
Fonte: Universidade Nova de Lisboa. Instituto de Tecnologia Química e Biológica. Publicador: Universidade Nova de Lisboa. Instituto de Tecnologia Química e Biológica.
Tipo: Tese de Doutorado
Publicado em /12/2013 ENG
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Dissertation presented to obtain the Ph.D degree in Biochemistry.; Aerobic respiratory chains are composed of a series of membrane complexes that catalyze the electron transfer from reducing substrates to oxygen. The energy released through this process is used to translocate protons across the membranes, thus generating a proton motive force that activates F1FO-ATP synthase to synthesize ATP. The arrangement of these enzymes in the inner mitochondrial membrane is well characterized in mammalian mitochondria, where different sets of supramolecular assemblies, or supercomplexes, involving the majority of the respiratory complexes were described, reinforcing the idea of an operational solid state model wherein the oxidative phosphorylation processes are optimized.(...)

Supramolecular blueprint approach to metal-coordinated capsules

McKinlay, Robert M.; Cave, Gareth W. V.; Atwood, Jerry L.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
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An important problem in designing any large network is the assembly of systems that are resilient to change. From a chemical point of view, an analogy can be used where one requires supramolecular assemblies to maintain their dimensionality combined with limited structural perturbation in response to variation in its intermolecular framework. The identification of hydrogen-bonded framework patterns within experimentally known supramolecular assemblies that are structurally robust to disruption and selective hydrogen substitution are envisioned to act as a supramolecular blueprint or template for metal-ion retroinsertion. Here, we report the formation of a large neutral discrete pseudo-spherical coordination capsule assembled from 6 pyrogallol[4]arene ligands and 24 Cu(II) metal ions. Amazingly, this coordination capsule is structurally analogous to its hydrogen-bonded counterpart. This result shows a robust ability of pyrogallol[4]arene molecules to self-assemble into large hexameric cage structures from either the hydrogen-bonding or metal-ligand coordination process. The identification of robust supramolecular assemblies that conserve their structure in response to interchangeability between hydrogen-bonded networks for metal coordination...

Substrate-Dependent Morphology of Supramolecular Assemblies: Fibrillin and Type-VI Collagen Microfibrils

Sherratt, Michael J.; Holmes, David F.; Shuttleworth, C. Adrian; Kielty, Cay M.
Fonte: Biophysical Society Publicador: Biophysical Society
Tipo: Artigo de Revista Científica
Publicado em /05/2004 EN
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Substrate hydrophobicity/hydrophilicity has previously been shown to affect the morphology and biological function of isolated proteins. We have employed atomic force microscopy to investigate substrate dependent morphologies of two biochemically distinct native supramolecular assemblies: fibrillin and type-VI collagen microfibrils. These morphologically heterogeneous microfibrillar systems are found in many vertebrate tissues where they perform structural and cell-signaling roles. Fibrillin microfibrils adsorbed to a hydrophilic mica substrate adopted a diffuse morphology. Fibrillin microfibrils adsorbed to mica coated with poly-l-lysine or to borosilicate glass substrates had a more compact morphology and a directional asymmetry to the bead, which was not present on mica alone. Intermediate morphologies were observed along a substrate gradient. The classical double-beaded appearance of type-VI collagen microfibrils was evident on mica coated with poly-l-lysine and on glass. On hydrophilic mica, morphology was severely disrupted and there was a major conformational reorganization along the whole collagen microfibril repeat. These observations of substrate dependent conformation have important implications for the interpretation of data from in vitro protein interaction assays and cellular signaling studies. Furthermore...

Diatom Adhesive Mucilage Contains Distinct Supramolecular Assemblies of a Single Modular Protein

Dugdale, T. M.; Dagastine, R.; Chiovitti, A.; Wetherbee, R.
Fonte: Biophysical Society Publicador: Biophysical Society
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
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A previous study used atomic force microscopy saw-tooth retraction curves to characterize the adhesive mucilage pads of the diatom Toxarium undulatum. The major mucilage component consisted of adhesive nanofibers (ANFs) made up of modular proteins arranged into cohesive units, each containing a set number of modular proteins aligned in parallel. This study shows that T. undulatum adhesive mucilage is a biocomposite containing four additional adhesive components, including single modular proteins that are likely to be the structural units from which the ANFs are assembled. Two further distinct supramolecular assemblies were observed to coexist with ANFs (ANFs II and III), along with a continuum of single modular proteins through oligomers made up of varying numbers of modular proteins arranged in parallel. All components of the adhesive biocomposite produce a characteristic force spectrum with the same interpeak distance (35.3 ± 0.3 (mean ± SE) nm), suggesting they are derived from discrete supramolecular assemblies of the same modular protein, but they are distinguishable from one another based on the rupture force, persistence length, and interpeak force measured from their saw-tooth curves.

Molecular and Supramolecular Structural Studies on Human Tropoelastin Sequences

Ostuni, Angela; Bochicchio, Brigida; Armentano, Maria F.; Bisaccia, Faustino; Tamburro, Antonio M.
Fonte: The Biophysical Society Publicador: The Biophysical Society
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
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One of the unusual properties of elastin is its ability to coacervate, which has been proposed to play an important role in the alignment of monomeric elastin for cross-linking into the polymeric elastin matrix. The temperature at which this transition takes place depends on several factors including protein concentration, ionic strength, and pH. Previously, polypeptide sequences encoded by different exons of the human tropoelastin gene have been analyzed for their ability to coacervate and to self-assemble. Few of them were indeed able to coacervate and only one, that encoded by exon 30 (EX30), gave amyloid fibers. In this article, we report on two chemically synthesized peptides—a decapeptide and an octadecapeptide—whose sequences are contained in the longer EX30 peptide and on a polypeptide (EX1–7) of 125 amino-acid residues corresponding to the sequence coded by the exons 1–7 and on a polypeptide (EX2–7) of 99 amino-acid residues encoded by exons 2–7 of human tropoelastin obtained by recombinant DNA techniques. Molecular and supramolecular structural characterization of these peptides showed that a minimum sequence of ∼20 amino acids is needed to form amyloid fibers in the exon 30-derived peptides. The N-terminal region of mature tropoelastin (EX2–7) gives rise to a coacervate and forms elastinlike fibers...

Exploiting genomic patterns to discover new supramolecular protein assemblies

Beeby, Morgan; Bobik, Thomas A; Yeates, Todd O
Fonte: Wiley Subscription Services, Inc., A Wiley Company Publicador: Wiley Subscription Services, Inc., A Wiley Company
Tipo: Artigo de Revista Científica
EN
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Bacterial microcompartments are supramolecular protein assemblies that function as bacterial organelles by compartmentalizing particular enzymes and metabolic intermediates. The outer shells of these microcompartments are assembled from multiple paralogous structural proteins. Because the paralogs are required to assemble together, their genes are often transcribed together from the same operon, giving rise to a distinctive genomic pattern: multiple, typically small, paralogous proteins encoded in close proximity on the bacterial chromosome. To investigate the generality of this pattern in supramolecular assemblies, we employed a comparative genomics approach to search for protein families that show the same kind of genomic pattern as that exhibited by bacterial microcompartments. The results indicate that a variety of large supramolecular assemblies fit the pattern, including bacterial gas vesicles, bacterial pili, and small heat-shock protein complexes. The search also retrieved several widely distributed protein families of presently unknown function. The proteins from one of these families were characterized experimentally and found to show a behavior indicative of supramolecular assembly. We conclude that cotranscribed paralogs are a common feature of diverse supramolecular assemblies...

Electrostatic Control of Peptide Side-Chain Reactivity using Amphiphilic Homopolymer-based Supramolecular Assemblies

Wang, Feng; Gomez-Escudero, Andrea; Ramireddy, Rajasekhar R.; Murage, Gladys; Thayumanavan, S.; Vachet, Richard W.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
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46.87%
Supramolecular assemblies formed by amphiphilic homopolymers with negatively charged groups in the hydrophilic segment have been designed to enable high labeling selectivity towards reactive side chain functional groups in peptides. The negatively-charged interiors of the supramolecular assemblies are found to block the reactivity of protonated amines that would otherwise be reactive in aqueous solution, while maintaining the reactivity of non-protonated amines. Simple changes to the pH of the assemblies’ interiors allow control over the reactivity of different functional groups in a manner that is dependent on the pKa of a given peptide functional group. The labeling studies carried out in positively charged supramolecular assemblies and free buffer solution show that, even when the amine is protonated, labeling selectivity exists only when complementary electrostatic interactions are present, thereby demonstrating the electrostatically controlled nature of these reactions.

Luminescence color switching of supramolecular assemblies of discrete molecular decanuclear gold(I) sulfido complexes

Hau, Franky Ka-Wah; Lee, Terence Kwok-Ming; Cheng, Eddie Chung-Chin; Au, Vonika Ka-Man; Yam, Vivian Wing-Wah
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
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Polynuclear gold(I) complexes have attracted enormous attention over the past decades owing to their intriguing luminescence behavior and their interesting structural and bonding properties, especially with regard to their propensity to form noncovalent short gold–gold contacts. Most works in polynuclear gold(I) clusters involve structural studies in the solid state, with less attention focused on supramolecular assembly in solution. Herein, discrete decanuclear gold(I) μ3-sulfido complexes with long alkyl chains are found to form supramolecular assemblies with different luminescence and morphologies that are tunable by solvent modulation. This has demonstrated the importance of the control and manipulation of intercluster assembly in influencing the photophysical properties and morphologies of the clusters. Such findings have not been previously reported in discrete molecular gold(I) systems.

Macromolecularly crowded in vitro microenvironments accelerate the production of extracellular matrix-rich supramolecular assemblies

Kumar, Pramod; Satyam, Abhigyan; Fan, Xingliang; Collin, Estelle; Rochev, Yury; Rodriguez, Brian J.; Gorelov, Alexander; Dillon, Simon; Joshi, Lokesh; Raghunath, Michael; Pandit, Abhay; Zeugolis, Dimitrios I.
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
EN_US
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46.52%
Therapeutic strategies based on the principles of tissue engineering by self-assembly put forward the notion that functional regeneration can be achieved by utilising the inherent capacity of cells to create highly sophisticated supramolecular assemblies. However, in dilute ex vivo microenvironments, prolonged culture time is required to develop an extracellular matrix-rich implantable device. Herein, we assessed the influence of macromolecular crowding, a biophysical phenomenon that regulates intra- and extra-cellular activities in multicellular organisms, in human corneal fibroblast culture. In the presence of macromolecules, abundant extracellular matrix deposition was evidenced as fast as 48 h in culture, even at low serum concentration. Temperature responsive copolymers allowed the detachment of dense and cohesive supramolecularly assembled living substitutes within 6 days in culture. Morphological, histological, gene and protein analysis assays demonstrated maintenance of tissue-specific function. Macromolecular crowding opens new avenues for a more rational design in engineering of clinically relevant tissue modules in vitro.

Electrospinning and characterization of supramolecular poly(4-vinyl pyridine)-small molecule complexes

Wang, Xiaoxiao
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
EN
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46.55%
La chimie supramoléculaire est basée sur l'assemblage non covalent de blocs simples, des petites molécules aux polymères, pour synthétiser des matériaux fonctionnels ou complexes. La poly(4-vinylpyridine) (P4VP) est l'une des composantes supramoléculaires les plus utilisées en raison de sa chaîne latérale composée d’une pyridine pouvant interagir avec de nombreuses espèces, telles que les petites molécules monofonctionnelles et bifonctionnelles, grâce à divers types d'interactions. Dans cette thèse, des assemblages supramoléculaires de P4VP interagissant par liaisons hydrogène avec de petites molécules sont étudiés, en ayant comme objectifs de faciliter l'électrofilage de polymères et de mieux comprendre et d'optimiser la photoréponse des matériaux contenant des dérivés d'azobenzène. Une nouvelle approche est proposée afin d'élargir l'applicabilité de l'électrofilage, une technique courante pour produire des nanofibres. À cet effet, un complexe entre la P4VP et un agent de réticulation bifonctionnel capable de former deux liaisons hydrogène, le 4,4'-biphénol (BiOH), a été préparé pour faciliter le processus d’électrofilage des solutions de P4VP. Pour mieux comprendre ce complexe, une nouvelle méthode de spectroscopie infrarouge (IR) a d'abord été développée pour quantifier l'étendue de la complexation. Elle permet de déterminer un paramètre clé...

Macromolecularly crowded in vitro microenvironments accelerate the production of extracellular matrix-rich supramolecular assemblies

Kumar, Pramod; Satyam, Abhigyan; Fan, Xingliang; Collin, Estelle; Rochev, Yury; Rodriguez, Brian J.; Gorelov, Alexander; Dillon, Simon; Joshi, Lokesh; Raghunath, Michael; Pandit, Abhay; Zeugolis, Dimitrios I.
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 04/03/2015 EN
Relevância na Pesquisa
46.52%
Therapeutic strategies based on the principles of tissue engineering by self-assembly put forward the notion that functional regeneration can be achieved by utilising the inherent capacity of cells to create highly sophisticated supramolecular assemblies. However, in dilute ex vivo microenvironments, prolonged culture time is required to develop an extracellular matrix-rich implantable device. Herein, we assessed the influence of macromolecular crowding, a biophysical phenomenon that regulates intra- and extra-cellular activities in multicellular organisms, in human corneal fibroblast culture. In the presence of macromolecules, abundant extracellular matrix deposition was evidenced as fast as 48 h in culture, even at low serum concentration. Temperature responsive copolymers allowed the detachment of dense and cohesive supramolecularly assembled living substitutes within 6 days in culture. Morphological, histological, gene and protein analysis assays demonstrated maintenance of tissue-specific function. Macromolecular crowding opens new avenues for a more rational design in engineering of clinically relevant tissue modules in vitro.

Peptides and Gd Complexes Containing Colloidal Assemblies as Tumor-Specific Contrast Agents in MRI: Physicochemical Characterization

Vaccaro, Mauro; Accardo, Antonella; D'Errico, Gerardino; Schillén, Karin; Radulescu, Aurel; Tesauro, Diego; Morelli, Giancarlo; Paduano, Luigi
Fonte: The Biophysical Society Publicador: The Biophysical Society
Tipo: Artigo de Revista Científica
EN
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46.52%
The aggregation behavior of an amphiphilic supramolecular system, with potential application as a tumor-specific magnetic resonance imaging contrast agent, has been studied in detail by dynamic light scattering, small-angle neutron scattering and cryotransmission electron microscopy. The system was constituted of mixed aggregates formed by an anionic unimer containing the DTPAGlu, a chelating agent for the paramagnetic Gd3+ ion, and an uncharged unimer containing the bioactive peptide CCK8, capable of directing the assembly toward tumor cells. Mixed aggregates formed by both unimers, and in the case of the DTPAGlu unimer with the chelating agent as free base or as Gd3+ complex, have been investigated. A number of interesting features of the aggregation behavior were revealed: at physiological pH, micelles and bilayer structures were present, whereas upon decreasing solution pH or increasing ionic strength, the formation of bilayer structures was favored. On the basis of the above observations, the aggregating mechanism has been elucidated by considering the screening effect on intra- and interaggregate electrostatic repulsions.

Redesigning Channel-Forming Peptides: Amino Acid Substitutions that Enhance Rates of Supramolecular Self-Assembly and Raise Ion Transport Activity

Shank, Lalida P.; Broughman, James R.; Takeguchi, Wade; Cook, Gabriel; Robbins, Ashley S.; Hahn, Lindsey; Radke, Gary; Iwamoto, Takeo; Schultz, Bruce D.; Tomich, John M.
Fonte: Biophysical Society Publicador: Biophysical Society
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.51%
Three series of 22-residue peptides derived from the transmembrane M2 segment of the glycine receptor α1-subunit (M2GlyR) have been designed, synthesized, and tested to determine the plasticity of a channel-forming sequence and to define whether channel pores with enhanced conductive properties could be created. Sixteen sequences were examined for aqueous solubility, solution-association tendency, secondary structure, and half-maximal concentration for supramolecular assembly, channel activity, and ion transport properties across epithelial monolayers. All peptides interact strongly with membranes: associating with, inserting across, and assembling to form homooligomeric bundles when in micromolar concentrations. Single and double amino acid replacements involving arginine and/or aromatic amino acids within the final five C-terminal residues of the peptide cause dramatic effects on the concentration dependence, yielding a range of K1/2 values from 36 ± 5 to 390 ± 220 μM for transport activity. New water/lipid interfacial boundaries were established for the transmembrane segment using charged or aromatic amino acids, thus limiting the peptides' ability to move perpendicularly to the plane of the bilayer. Formation of discrete water/lipid interfacial boundaries appears to be necessary for efficient supramolecular assembly and high anion transport activity. A peptide sequence is identified that may show efficacy in channel replacement therapy for channelopathies such as cystic fibrosis.

Hofmeister effects in supramolecular and biological systems

Lo Nostro, Pierandrea; Ninham, Barry; Milani, Silvia; Lo Nostro, Antonella; Pesavento, Giovanna; Baglioni, Piero
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.44%
Specific ion effects, representative of near-universal Hofmeister phenomena, are illustrated in three different systems. These are the formation of supramolecular assemblies from cyclodextrins, the optical rotation of l-serine, and the growth rate of two

Molecular Recognition in Host-Guest Ionophore-Siderophore Assemblies

Tristani, Esther Marie
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação Formato: 29967873 bytes; application/pdf
Publicado em //2010 EN_US
Relevância na Pesquisa
47.03%

This work examines the characterization of supramolecular assemblies and, more specifically, host-guest complexes involved in molecular recognition events. The supramolecular assemblies studied take root from metal ion delivery in biological uptake pathways, specifically the delivery of iron to microbial cells. These assemblies are studied in an effort to further understand the nature of molecular recognition events, specifically the nature and strength of interactions between a host and a guest, and possible applications of these systems.

The development of a mass spectral method by which to characterize supramolecular assemblies involving the cation binding hosts 18-crown-6, benzo-18-crown-6, dicyclohexano-18-crown-6, and dibenzo-18-crown-6 macrocycles, and the linear ionophore lasalocid with cationic guests, including substituted protonated amines and the iron siderophore ferrioxamine B is presented. Methodology was developed using ESI-MS to successfully quantitate host-guest interactions in binary and complex mixtures. Binding constants were obtained in the range of log Ka = 3 - 5 and correspond to similar systems previously studied in the literature. The studies presented here further our understanding of the molecular recognition events that must occur between a siderophore and a receptor and provide an improved method by which to measure the strength of their interaction.

The effects of redox hosts on host-guest complex formation with ferrioxamine B and the characterization of the host-guest complexes formed and the strength of the interactions between them were studied using cyclic voltammetry...

Self-assembly of supramolecular platinum complexes with bis-4-pyridyl cavitands

Jude, Hershel; Sinclair, David; Das, Neeladri; Sherburn, Michael; Stang, Peter J
Fonte: American Chemical Society Publicador: American Chemical Society
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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The design and self-assembly of six new supramolecular complexes (four triangles and two 2+2 assemblies) are described. These assemblies incorporate two new bispyridyl cavitand building blocks and were prepared in excellent yields (85-95%). The assemblies and building blocks were characterized with multinuclear NMR spectroscopy, electrospray ionization mass spectrometry, and elemental analysis. Isotopically resolved mass spectrometry along with NMR data confirms the existence of the six assemblies.