Articoli di riviste sul tema "Interactions directes de surface"
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1
Hoffecker, Ian T., Alan Shaw, Viktoria Sorokina, Ioanna Smyrlaki e Björn Högberg. "Stochastic modeling of antibody binding predicts programmable migration on antigen patterns". Nature Computational Science 2, n. 3 (marzo 2022): 179–92. http://dx.doi.org/10.1038/s43588-022-00218-z.
Abstract (sommario):
AbstractViruses and bacteria commonly exhibit spatial repetition of the surface molecules that directly interface with the host immune system. However, the complex interaction of patterned surfaces with immune molecules containing multiple binding domains is poorly understood. We developed a pipeline for constructing mechanistic models of antibody interactions with patterned antigen substrates. Our framework relies on immobilized DNA origami nanostructures decorated with precisely placed antigens. The results revealed that antigen spacing is a spatial control parameter that can be tuned to influence the antibody residence time and migration speed. The model predicts that gradients in antigen spacing can drive persistent, directed antibody migration in the direction of more stable spacing. These results depict antibody–antigen interactions as a computational system where antigen geometry constrains and potentially directs the antibody movement. We propose that this form of molecular programmability could be exploited during the co-evolution of pathogens and immune systems or in the design of molecular machines.
2
Tao, Feng. "Nanoscale surface chemistry in self- and directed-assembly of organic molecules on solid surfaces and synthesis of nanostructured organic architectures". Pure and Applied Chemistry 80, n. 1 (1 gennaio 2008): 45–57. http://dx.doi.org/10.1351/pac200880010045.
Abstract (sommario):
This article briefly reviews the interplay of weak noncovalent interactions involved in the formation of self-assembled monolayers of organic molecules and the strong chemical binding in directed-assembly of organic molecules on solid surfaces. For a self-assembled monolayer, each molecule involves at least three categories of weak interactions, including molecule-substrate interactions, molecule-molecule interactions in a lamella, and molecule-molecule interactions between two adjacent lamellae. Basically, molecule-substrate interactions play a major role in determining molecular configuration. Molecule-molecule interactions, particularly the interactions of molecular ending functional groups between two adjacent lamellae, such as hydrogen bonds, play a dominant role in determining the molecular packing pattern in a monolayer. These weak interactions may induce or influence molecular chirality. This understanding at the atomic scale allows us to design 2D nanostructured organic materials via precisely manipulating these weak noncovalent interactions. Compared to the self-assembled monolayer formed via weak noncovalent interactions, the structure of directed-assembled monolayer/multilayers formed through strong chemical bonds is significantly dependent on the geometric arrangement and reactivity of active sites on the solid surface. In contrast to the significant role of weak intermolecular interactions in determining molecular packing in a self-assembled monolayer, strong chemical binding between molecules and reactive sites of a substrate plays a major role in determining the molecular packing pattern in a directed-assembly monolayer. Controllable chemical attachment between organic functional groups and reactive sites of the solid surface is crucial for the formation of a highly oriented organic monolayer and the following multilayer.
3
Ma, Lu-Yan, Glenn King e Lawrence Rothfield. "Mapping the MinE Site Involved in Interaction with the MinD Division Site Selection Protein of Escherichia coli". Journal of Bacteriology 185, n. 16 (15 agosto 2003): 4948–55. http://dx.doi.org/10.1128/jb.185.16.4948-4955.2003.
Abstract (sommario):
ABSTRACT Interactions between the MinD and MinE proteins are required for proper placement of the Escherichia coli division septum. The site within MinE that is required for interaction with MinD was mapped by studying the effects of site-directed minE mutations on MinD-MinE interactions in yeast two-hybrid and three-hybrid experiments. This confirmed that the MinE N-terminal domain is responsible for the interaction of MinE with MinD. Mutations that interfered with the interaction defined an extended surface on one face of the α-helical region of the MinE N-terminal domain, consistent with the idea that the MinE-MinD interaction involves formation of a coiled-coil structure by interaction with a complementary helical surface within MinD.
4
Christianson, Dawn R., Andrey S. Dobroff, Bettina Proneth, Amado J. Zurita, Ahmad Salameh, Eleonora Dondossola, Jun Makino et al. "Ligand-directed targeting of lymphatic vessels uncovers mechanistic insights in melanoma metastasis". Proceedings of the National Academy of Sciences 112, n. 8 (6 febbraio 2015): 2521–26. http://dx.doi.org/10.1073/pnas.1424994112.
Abstract (sommario):
Metastasis is the most lethal step of cancer progression in patients with invasive melanoma. In most human cancers, including melanoma, tumor dissemination through the lymphatic vasculature provides a major route for tumor metastasis. Unfortunately, molecular mechanisms that facilitate interactions between melanoma cells and lymphatic vessels are unknown. Here, we developed an unbiased approach based on molecular mimicry to identify specific receptors that mediate lymphatic endothelial–melanoma cell interactions and metastasis. By screening combinatorial peptide libraries directly on afferent lymphatic vessels resected from melanoma patients during sentinel lymphatic mapping and lymph node biopsies, we identified a significant cohort of melanoma and lymphatic surface binding peptide sequences. The screening approach was designed so that lymphatic endothelium binding peptides mimic cell surface proteins on tumor cells. Therefore, relevant metastasis and lymphatic markers were biochemically identified, and a comprehensive molecular profile of the lymphatic endothelium during melanoma metastasis was generated. Our results identified expression of the phosphatase 2 regulatory subunit A, α-isoform (PPP2R1A) on the cell surfaces of both melanoma cells and lymphatic endothelial cells. Validation experiments showed that PPP2R1A is expressed on the cell surfaces of both melanoma and lymphatic endothelial cells in vitro as well as independent melanoma patient samples. More importantly, PPP2R1A-PPP2R1A homodimers occur at the cellular level to mediate cell–cell interactions at the lymphatic–tumor interface. Our results revealed that PPP2R1A is a new biomarker for melanoma metastasis and show, for the first time to our knowledge, an active interaction between the lymphatic vasculature and melanoma cells during tumor progression.
5
Linne, Christine, Daniele Visco, Stefano Angioletti-Uberti, Liedewij Laan e Daniela J. Kraft. "Direct visualization of superselective colloid-surface binding mediated by multivalent interactions". Proceedings of the National Academy of Sciences 118, n. 36 (31 agosto 2021): e2106036118. http://dx.doi.org/10.1073/pnas.2106036118.
Abstract (sommario):
Reliably distinguishing between cells based on minute differences in receptor density is crucial for cell–cell or virus–cell recognition, the initiation of signal transduction, and selective targeting in directed drug delivery. Such sharp differentiation between different surfaces based on their receptor density can only be achieved by multivalent interactions. Several theoretical and experimental works have contributed to our understanding of this “superselectivity.” However, a versatile, controlled experimental model system that allows quantitative measurements on the ligand–receptor level is still missing. Here, we present a multivalent model system based on colloidal particles equipped with surface-mobile DNA linkers that can superselectively target a surface functionalized with the complementary mobile DNA-linkers. Using a combined approach of light microscopy and Foerster resonance energy transfer (FRET), we can directly observe the binding and recruitment of the ligand–receptor pairs in the contact area. We find a nonlinear transition in colloid-surface binding probability with increasing ligand or receptor concentration. In addition, we observe an increased sensitivity with weaker ligand–receptor interactions, and we confirm that the timescale of binding reversibility of individual linkers has a strong influence on superselectivity. These unprecedented insights on the ligand–receptor level provide dynamic information into the multivalent interaction between two fluidic membranes mediated by both mobile receptors and ligands and will enable future work on the role of spatial–temporal ligand–receptor dynamics on colloid-surface binding.
6
Stanković, Igor, Luis Lizardi e Carlos García. "Assembly of nanocube super-structures directed by surface and magnetic interactions". Nanoscale 12, n. 37 (2020): 19390–403. http://dx.doi.org/10.1039/d0nr03485a.
7
Wang, Sheng-Hung, Ying-Ta Wu, Sheng-Chu Kuo e John Yu. "HotLig: A Molecular Surface-Directed Approach to Scoring Protein–Ligand Interactions". Journal of Chemical Information and Modeling 53, n. 8 (agosto 2013): 2181–95. http://dx.doi.org/10.1021/ci400302d.
8
Carpick, Robert W., e Mark A. Eriksson. "Measurements of In-Plane Material Properties with Scanning Probe Microscopy". MRS Bulletin 29, n. 7 (luglio 2004): 472–77. http://dx.doi.org/10.1557/mrs2004.141.
Abstract (sommario):
AbstractScanning probe microscopy (SPM) was originally conceived as a method for measuring atomic-scale surface topography. Over the last two decades, it has blossomed into an array of techniques that can be used to obtain a rich variety of information about nanoscale material properties. With the exception of friction measurements, these techniques have traditionally depended on tip—sample interactions directed normal to the sample's surface. Recently, researchers have explored several effects arising from interactions parallel to surfaces, usually by deliberately applying a modulated lateral displacement. In fact, some parallel motion is ubiquitous to cantilever-based SPM, due to the tilt of the cantilever. Recent studies, performed in contact, noncontact, and intermittent-contact modes, provide new insights into properties such as structural anisotropy, lateral interactions with surface features, nanoscale shear stress and contact mechanics, and in-plane energy dissipation. The understanding gained from interpreting this behavior has consequences for all cantilever-based scanning probe microscopies.
9
Demir Kanmazalp, S., M. Sagher, N. Dege e H. Içbudak. "Synthesis, Hirshfeld Surface, FT-IR Analysis and Single Crystal X-Ray Structure of 2-amino-3-hydroxypyridinium saccharinate". Журнал структурной химии 64, n. 6 (2023): 112678. http://dx.doi.org/10.26902/jsc_id112678.
Abstract (sommario):
The title compound 2-amino-3-hydroxypyridinium saccharinate (AHPSAC) was synthesized and the obtaining single crystal was characterized by elemental analysis, XRD, 1H-NMR and FT-IR spectroscopic analyses. The title compound, AHPSAC, has a non-planar configuration and crystallized in the monoclinic crystal system with Cc space group with the sequent parameters: a = 11.9535 (11) Å, b = 9.1942 (9) Å, c = 13.2391 (12) Å, β = 115.608 (6)˚, V = 1312.1(2) Å3, Z = 4. The asymmetric unit contains one-half of a C5H7N2O molecule and one-half of a C7H4N1O3S1 molecule. The crystal packing is mainly directed by strong hydrogen bonding interactions observed N—H⋯N and N—H⋯O but, in addition, weak interaction such as π⋯π is also sighted. Hirshfeld surface analyses and 2D fingerprint graphs were accomplished to find out diverse bonding interactions in the AHPSAC compound. These results show that most of the contribution to the Hirshfeld surfaces came from O⋯H/ H⋯O (35.2%) contacts.
10
Superfine, R., M. R. Falvo, G. J. Clary, S. Paulson, R. M. Taylor, V. Chi, F. P. Brooks e S. Washburn. "Nanomanipulation for Material Properties, Substrate Interactions and Devices". Microscopy and Microanalysis 4, S2 (luglio 1998): 336–37. http://dx.doi.org/10.1017/s1431927600021802.
Abstract (sommario):
In many cases in experimental science, it is true that the instrument interface becomes a limiting factor in the efficacy of carrying out unusual experiments, or prevents the complete understanding of the acquired data. We are developing an advanced interface for Scanning Probe Microscopy (SPM) which allows intuitive rendering of datasets and natural instrument control, all in real-time. The interface, called the nanoManipulator, combines a high performance graphics engine for real-time data rendering with a haptic interface which places the human operator directly into the “feedback loop” that controls surface manipulations. In practice, the user holds a stylus in hand. By moving the stylus laterally, the user directs the movement of the SPM tip across the sample. The haptic interface enables the user to “feel” the surface by forcing the stylus to move up and down in response to the surface topography.
11
Cole, G. J., D. Schubert e L. Glaser. "Cell-substratum adhesion in chick neural retina depends upon protein-heparan sulfate interactions." Journal of Cell Biology 100, n. 4 (1 aprile 1985): 1192–99. http://dx.doi.org/10.1083/jcb.100.4.1192.
Abstract (sommario):
Embryonic chick neural retina cells in culture release complexes of proteins and glycosaminoglycans, termed adherons, which stimulate cell-substratum adhesion when adsorbed to nonadhesive surfaces. Two distinct retinal cell surface macromolecules, a 170,000-mol-wt glycoprotein and a heparan sulfate proteoglycan; are components of adherons that can independently promote adhesion when coated on inert surfaces. The 170,000-mol-wt polypeptide contains a heparin-binding domain, as indicated by its retention on heparin-agarose columns and its ability to bind [3H]heparin in solution. The attachment of embryonic chick retinal cells to the 170,000-mol-wt protein also depends upon interactions between the protein and the heparan sulfate proteoglycan, since heparan sulfate in solution disrupts adhesion of chick neural retina cells to glass surfaces coated with the 170,000-mol-wt protein. This adhesion is not impaired by chondroitin sulfate or hyaluronic acid, which indicates that inhibition by heparan sulfate is specific. Polyclonal antisera directed against the cell surface heparan sulfate proteoglycan also inhibit attachment of retinal cells to the 170,000-mol-wt protein, which suggests that cell-adheron binding is mediated in part by interactions between cell surface heparan sulfate proteoglycan and 170,000-mol-wt protein contained in the adheron particles. Previous studies have indicated that this type of cell-substratum adhesion is tissue-specific since retina cells do not attach to muscle adherons. Schubert D., M. LaCorbiere, F. G. Klier, and C. Birdwell, 1983, J. Cell Biol. 96:990-998.
12
Watterson, Daniel, Bostjan Kobe e Paul R. Young. "Residues in domain III of the dengue virus envelope glycoprotein involved in cell-surface glycosaminoglycan binding". Journal of General Virology 93, n. 1 (1 gennaio 2012): 72–82. http://dx.doi.org/10.1099/vir.0.037317-0.
Abstract (sommario):
The dengue virus (DENV) envelope (E) protein mediates virus entry into cells via interaction with a range of cell-surface receptor molecules. Cell-surface glycosaminoglycans (GAGs) have been shown to play an early role in this interaction, and charged oligosaccharides such as heparin bind to the E protein. We have examined this interaction using site-directed mutagenesis of a recombinant form of the putative receptor-binding domain III of the DENV-2E protein expressed as an MBP (maltose-binding protein)-fusion protein. Using an ELISA-based GAG-binding assay, cell-based binding analysis and antiviral-activity assays, we have identified two critical residues, K291 and K295, that are involved in GAG interactions. These studies have also demonstrated differential binding between mosquito and human cells.
13
Wu, Ya-Ping, Haiko J. Bloemendal, Emile E. Voest, Ton Logtenberg, Philip G. de Groot, Martijn F. B. G. Gebbink e Hetty C. de Boer. "Fibrin-incorporated vitronectin is involved in platelet adhesion and thrombus formation through homotypic interactions with platelet-associated vitronectin". Blood 104, n. 4 (15 agosto 2004): 1034–41. http://dx.doi.org/10.1182/blood-2003-12-4293.
Abstract (sommario):
AbstractWhen a blood clot is formed, vitronectin (VN) is incorporated. Here we studied the consequence of VN incorporation for platelet interactions under flow. Perfusion of whole blood over a fibrin network, formed from purified fibrinogen, resulted in approximately 20% surface coverage with blood platelets. Incorporation of purified multimeric VN into the fibrin network resulted in a 2-fold increase in surface coverage with platelets and in enhancement of platelet aggregate formation. A human monoclonal antibody (huMab VN18), directed against the multimeric form of VN, inhibited platelet adhesion to the combined fibrin/VN matrix to the level of adhesion on fibrin alone. This inhibition was also shown when whole blood was perfused over a plasma-derived clot. Surprisingly, the inhibitory action of the antibody was not directed toward VN incorporated into the fibrin network but toward VN released from the platelets. We conclude that VN-potentiated platelet-clot interaction requires VN in the clot and multimeric VN bound to the platelet surface. Our results provide evidence that homotypic VN interactions contribute to platelet adhesion and aggregation to a blood clot. This report demonstrates for the first time that self-assembly of VN may provide a physiologically relevant contribution to platelet aggregation on a blood clot.
14
Blouin, Christian, J. Guy Guillemette e Carmichael JA Wallace. "Probing electrostatic interactions in cytochrome c using site-directed chemical modification". Biochemistry and Cell Biology 80, n. 2 (1 aprile 2002): 197–203. http://dx.doi.org/10.1139/o01-238.
Abstract (sommario):
This communication reports the generation of an electrostatic probe using chemical modification of methionine side chains. The alkylation of methionine by iodoacetamide was achieved in a set of Saccharomyces cerevisiae iso-1-cytochrome c mutants, introducing the nontitratable, nondelocalized positive charge of a carboxyamidomethylmethionine sulfonium (CAMMS) ion at five surface and one buried site in the protein. Changes in redox potential and its variation with temperature were used to calculate microscopic effective dielectric constants operating between the probe and the heme iron. Dielectric constants (ε) derived from ΔΔG values were not useful due to entropic effects, but εΔΔH gave results that supported the theory. The effect on biological activity of surface derivatization was interpreted in terms of proteinprotein interactions. The introduction of an electrostatic probe in cytochrome c often resulted in marked effects on activity with one of two physiological partners: cytochrome c reductase, especially if introduced at position 65, and cytochrome c oxidase, if at position 28.Key words: protein engineering, chemical modification, cytochrome c, electron transport, protein electrostatics, redox potential control.
15
Dodson, Brian W., e Paul A. Taylor. "Interaction of a 10 eV silicon beam with the Si(111) surface: A molecular dynamics study". Journal of Materials Research 2, n. 6 (dicembre 1987): 805–8. http://dx.doi.org/10.1557/jmr.1987.0805.
Abstract (sommario):
The interaction of a low-energy silicon beam with a silicon substrate has been simulated. The combined effects of vibrational lattice excitation and of covalent binding have been included for the first time by using a molecular dynamics technique and an empirical potential that accurately describes the covalent Si–Si interactions. A 10 eV silicon beam was directed normal to a silicon (111) substrate. Sticking ratio, penetration depth, substrate structure, and vibrational excitation of the substrate are quantitatively determined. The special features of such low-energy beam deposition relative to thermal deposition processes are discussed.
16
Boukerche, H., O. Berthier-Vergnes, E. Tabone, JF Dore, LL Leung e JL McGregor. "Platelet-melanoma cell interaction is mediated by the glycoprotein IIb- IIIa complex". Blood 74, n. 2 (1 agosto 1989): 658–63. http://dx.doi.org/10.1182/blood.v74.2.658.bloodjournal742658.
Abstract (sommario):
A human malignant melanoma cell line (M3Dau) was observed by electron microscopy to interact directly with human platelets and induced platelet aggregation. Fab fragments of a monoclonal antibody MoAb (LYP18), directed against the platelet glycoprotein (GP) IIb-IIIa complex, inhibited platelet-melanoma interactions and platelet-platelet aggregation. M3Dau melanoma cells bind LYP 18 and synthesize IIb-IIIa- like GPs. When the melanoma cells were preincubated with LYP 18, tumor- platelet interaction did not occur, suggesting that the interaction may be mediated by the IIb-IIIa-like GPs present on the melanoma cell surface. Glanzmann's thrombasthenic platelets, lacking GPIIb and IIIa, did not interact with melanoma cells, indicating that the platelet GPIIb-IIIa complex is also necessary for the platelet-melanoma cell interaction. This work demonstrates the importance of the IIb-IIIa-like GPs, present on M3Dau melanoma cells, in mediating tumor-platelet interactions.
17
O'Shea, P. "Intermolecular interactions with/within cell membranes and the trinity of membrane potentials: kinetics and imaging". Biochemical Society Transactions 31, n. 5 (1 ottobre 2003): 990–96. http://dx.doi.org/10.1042/bst0310990.
Abstract (sommario):
The interactions of (macro-)molecules with biological membranes underlies much of cell biology. This paper outlines many of the factors that must be taken into account in order to understand fully the nature of these interactions. These include some roles of the membrane potentials including features of the surface and dipole potentials. Several fluorescence detection technologies directed towards these are outlined that offer high-resolution experimental determination of the intermolecular interactions by measuring small changes of these potentials resulting from specific interactions of many kinds of molecular species. The possibilities for making single-cell spatial imaging measurements of such interactions is also described. Examples are used to indicate the feasibility of identifying and tracking localized interactions on the membrane surface in real-time. Some of this work points to the possibility that the membrane dipole potential spatially varies about the cell surface, particularly within membrane microdomains such as ‘rafts’. Such variation is suggested to underlie the altered behaviour of signalling systems within rafts and offer the means of an additional level of biological control.
18
Tawia Hagan, Daniel Fiifi, Guojie Wang, X. San Liang e Han A. J. Dolman. "A Time-Varying Causality Formalism Based on the Liang–Kleeman Information Flow for Analyzing Directed Interactions in Nonstationary Climate Systems". Journal of Climate 32, n. 21 (7 ottobre 2019): 7521–37. http://dx.doi.org/10.1175/jcli-d-18-0881.1.
Abstract (sommario):
Abstract The interaction between the land surface and the atmosphere is of significant importance in the climate system because it is a key driver of the exchanges of energy and water. Several important relations to heat waves, floods, and droughts exist that are based on the interaction of soil moisture and, for instance, air temperature and humidity. Our ability to separate the elements of this coupling, identify the exact locations where they are strongest, and quantify their strengths is, therefore, of paramount importance to their predictability. A recent rigorous causality formalism based on the Liang–Kleeman (LK) information flow theory has been shown, both theoretically and in real-world applications, to have the necessary asymmetry to infer the directionality and magnitude within geophysical interactions. However, the formalism assumes stationarity in time, whereas the interactions within the land surface and atmosphere are generally nonstationary; furthermore, it requires a sufficiently long time series to ensure statistical sufficiency. In this study, we remedy this difficulty by using the square root Kalman filter to estimate the causality based on the LK formalism to derive a time-varying form. Results show that the new formalism has similar properties compared to its time-invariant form. It is shown that it is also able to capture the time-varying causality structure within soil moisture–air temperature coupling. An advantage is that it does not require very long time series to make an accurate estimation. Applying a wavelet transform to the results also reveals the full range of temporal scales of the interactions.
19
Wilson, L., e J. W. Head. "Heat transfer in volcano–ice interactions on Earth". Annals of Glaciology 45 (2007): 83–86. http://dx.doi.org/10.3189/172756407782282507.
Abstract (sommario):
AbstractThe very high temperature contrast between magma/ lava and water ice commonly leads to the assumption that significant melting will take place immediately upon magma/ lava ice contact, yet observations of active flows show little evidence of voluminous melting upon contact. We use analytical thermal models to reassess the efficiency with which heat can be transferred from magma to ice in three situations: lava flows erupted on top of glacial ice, sill intrusions beneath glacial ice evolving into subglacial lava flows and dyke intrusions into the interiors of glaciers. We find that the maximum ratios of thickness of ice that can be melted to the thickness of magmatic heat source are likely to be ∽2–5 for subaerial lava flows encroaching onto glaciers, ∽6–7 for subglacial lava flows and ∽10 for dykes intruded into glacial ice. Rates of ice melt production are not linear functions of time and flow thickness, however, and this may account for the observations of minimal immediate water release from beneath advancing lava flows. Field observations during future eruptions should be directed at measuring the temperature of released water.
20
Knudson, C. B. "Hyaluronan receptor-directed assembly of chondrocyte pericellular matrix." Journal of Cell Biology 120, n. 3 (1 febbraio 1993): 825–34. http://dx.doi.org/10.1083/jcb.120.3.825.
Abstract (sommario):
Initial assembly of extracellular matrix occurs within a zone immediately adjacent to the chondrocyte cell surface termed the cell-associated or pericellular matrix. Assembly within the pericellular matrix compartment requires specific cell-matrix interactions to occur, that are mediated via membrane receptors. The focus of this study is to elucidate the mechanisms of assembly and retention of the cartilage pericellular matrix proteoglycan aggregates important for matrix organization. Assembly of newly synthesized chondrocyte pericellular matrices was inhibited by the addition to hyaluronan hexasaccharides, competitive inhibitors of the binding of hyaluronan to its cell surface receptor. Fully assembled chondrocyte pericellular matrices were displaced using hyaluronan hexasaccharides as well. When exogenous hyaluronan was added to matrix-free chondrocytes in combination with aggrecan, a pericellular matrix equivalent in size to an endogenous matrix formed within 30 min of incubation. Addition of hyaluronan and aggrecan to glutaraldehyde-fixed chondrocytes resulted in matrix assembly comparable to live chondrocytes. These matrices could be inhibited from assembling by the addition of excess hyaluronan hexasaccharides or displaced once assembled by subsequent incubation with hyaluronan hexasaccharides. The results indicate that the aggrecanrich chondrocyte pericellular matrix is not only on a scaffolding of hyaluronan, but actually anchored to the cell surface via the interaction between hyaluronan and hyaluronan receptors.
21
Boukerche, H., O. Berthier-Vergnes, E. Tabone, JF Dore, LL Leung e JL McGregor. "Platelet-melanoma cell interaction is mediated by the glycoprotein IIb- IIIa complex". Blood 74, n. 2 (1 agosto 1989): 658–63. http://dx.doi.org/10.1182/blood.v74.2.658.658.
Abstract (sommario):
Abstract A human malignant melanoma cell line (M3Dau) was observed by electron microscopy to interact directly with human platelets and induced platelet aggregation. Fab fragments of a monoclonal antibody MoAb (LYP18), directed against the platelet glycoprotein (GP) IIb-IIIa complex, inhibited platelet-melanoma interactions and platelet-platelet aggregation. M3Dau melanoma cells bind LYP 18 and synthesize IIb-IIIa- like GPs. When the melanoma cells were preincubated with LYP 18, tumor- platelet interaction did not occur, suggesting that the interaction may be mediated by the IIb-IIIa-like GPs present on the melanoma cell surface. Glanzmann's thrombasthenic platelets, lacking GPIIb and IIIa, did not interact with melanoma cells, indicating that the platelet GPIIb-IIIa complex is also necessary for the platelet-melanoma cell interaction. This work demonstrates the importance of the IIb-IIIa-like GPs, present on M3Dau melanoma cells, in mediating tumor-platelet interactions.
22
Edwards, D. N., P. Towb e S. A. Wasserman. "An activity-dependent network of interactions links the Rel protein Dorsal with its cytoplasmic regulators". Development 124, n. 19 (1 ottobre 1997): 3855–64. http://dx.doi.org/10.1242/dev.124.19.3855.
Abstract (sommario):
A signaling pathway active on the ventral side of the Drosophila embryo defines dorsoventral polarity. A cell surface signal relayed by Toll, Tube and Pelle releases the Rel-related protein Dorsal from its cytoplasmic inhibitor Cactus; free Dorsal translocates into nuclei and directs expression of ventral fates. Using the yeast two-hybrid system and immunoprecipitation experiments, we define scaffolding and anchoring interactions among the pathway components. We show that Dorsal binds specifically to Tube, Pelle and Cactus, and that the protein kinase activity of Pelle differentially regulates its interactions with Dorsal and Tube. We also identify Drosophila Filamin as a potential adaptor linking the interaction network, via Tube, to the transmembrane receptor Toll.
23
Wen-Chung Wang, H. Schachter, B. Elasir, Z. S. Wu e S. Onishi. "Acoustoelectric Interactions in Thin-Film Semiconductors Induced by Two Contra-Directed Surface Acoustic Waves". IEEE Transactions on Sonics and Ultrasonics 32, n. 5 (settembre 1985): 645–62. http://dx.doi.org/10.1109/t-su.1985.31648.
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Mackie, Duncan I., Natalie R. Nielsen, Matthew Harris, Smriti Singh, Reema B. Davis, Danica Dy, Graham Ladds e Kathleen M. Caron. "RAMP3 determines rapid recycling of atypical chemokine receptor-3 for guided angiogenesis". Proceedings of the National Academy of Sciences 116, n. 48 (11 novembre 2019): 24093–99. http://dx.doi.org/10.1073/pnas.1905561116.
Abstract (sommario):
Receptor-activity–modifying proteins (RAMPs) are single transmembrane-spanning proteins which serve as molecular chaperones and allosteric modulators of G-protein–coupled receptors (GPCRs) and their signaling pathways. Although RAMPs have been previously studied in the context of their effects on Family B GPCRs, the coevolution of RAMPs with many GPCR families suggests an expanded repertoire of potential interactions. Using bioluminescence resonance energy transfer-based and cell-surface expression approaches, we comprehensively screen for RAMP interactions within the chemokine receptor family and identify robust interactions between RAMPs and nearly all chemokine receptors. Most notably, we identify robust RAMP interaction with atypical chemokine receptors (ACKRs), which function to establish chemotactic gradients for directed cell migration. Specifically, RAMP3 association with atypical chemokine receptor 3 (ACKR3) diminishes adrenomedullin (AM) ligand availability without changing G-protein coupling. Instead, RAMP3 is required for the rapid recycling of ACKR3 to the plasma membrane through Rab4-positive vesicles following either AM or SDF-1/CXCL12 binding, thereby enabling formation of dynamic spatiotemporal chemotactic gradients. Consequently, genetic deletion of either ACKR3 or RAMP3 in mice abolishes directed cell migration of retinal angiogenesis. Thus, RAMP association with chemokine receptor family members represents a molecular interaction to control receptor signaling and trafficking properties.
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Singh, Satya Pal. "Spinodal Theory: A Common Rupturing Mechanism in Spinodal Dewetting and Surface Directed Phase Separation (Some Technological Aspects: Spatial Correlations and the Significance of Dipole-Quadrupole Interaction in Spinodal Dewetting)". Advances in Condensed Matter Physics 2011 (2011): 1–14. http://dx.doi.org/10.1155/2011/526397.
Abstract (sommario):
The emerging structures in spinodal dewetting of thin nano films and spinodal decomposition of binary mixtures are found to be similar with certain differences attributed to the nonlinearities inherent in the wetting forces. This paper deals with the technological aspects of the spinodal processes by giving a brief account of the theory and to correlate the two phenomena termed as spinodal dewetting of thin nanofilms and surface-directed phase separation. The MC simulation micrographs at early stage of spinodal dewetting of a (linear) polymer film confined between two hard walls (using FENE potential between the beads on same chain and Morse potential between inter and intra chain beads) show similarities with surface-directed phase separation (using metropolis algorithm) in creation of holes. The spinodal dewetting is also criticized on the basis of global minimization of free energy emerging from dipole-quadrupole interactions. A novel molecular scale-driving mechanism coming from asymmetric interface formation in spinodal processes is also proposed. It can be believed that the modeling done with the films under confinement of two walls works as a classical mathematical ansatz to the dipole-quadrupole interaction coming from quantum origins and giving rise to lateral interactions in the process reflecting a colossal behavior in thin nano films though weak in nature.
26
Burleigh, A. L., F. B. Horak e F. Malouin. "Modification of postural responses and step initiation: evidence for goal-directed postural interactions". Journal of Neurophysiology 72, n. 6 (1 dicembre 1994): 2892–902. http://dx.doi.org/10.1152/jn.1994.72.6.2892.
Abstract (sommario):
1. In this study, the interaction between anticipatory postural adjustments for step initiation and automatic postural responses to an external perturbation were investigated by having subjects initiate a voluntary forward step while perturbed by a backward surface translation, which caused forward sway of the body. The postural adjustments for step initiation act to move the body center of mass (COM) forward, whereas the automatic postural responses act to move the COM backward to restore stance equilibrium. Because the postural behaviors are in opposition, we asked whether a temporal hierarchy exists in which automatic postural responses are executed to restore equilibrium and followed by stereotypic postural adjustments for step initiation, or whether the interaction between these two postural behaviors is more dynamic. 2. Lower extremity electromyographs (EMGs), ground reaction forces, and kinematics were recorded from 10 subjects during three conditions: to quantify the anticipatory postural adjustments for step initiation, subjects stepped forward as soon as they felt a proprioceptive cue; to quantify the automatic postural responses to perturbation, subjects maintained stance equilibrium in response to a backward surface translation under both feet; and to quantify the interaction between the postural adjustments for the voluntary step and the automatic responses to the perturbation, subjects were exposed to a backward surface translation and instructed to step forward as soon as they felt the platform begin to move. 3. The anticipatory adjustments for step initiation included tibialis activation [stance limb = 163 +/- 28 (SE) ms; swing limb = 173 +/- 33 ms] and soleus inhibition resulting in center of foot pressure (COP) moving backward and lateral toward the swing limb to propel the COM forward over the stance limb. Subsequently, activation of the swing limb gastrocnemius resulted in heel-off. In contrast, the automatic postural adjustments for maintenance of stance equilibrium during a backward surface translation included activation of soleus and gastrocnemius (104 +/- 23 ms and 115 +/- 14 ms, respectively) resulting in a symmetrical forward displacement of the COP that moved the COM back to its original position with respect to the feet. 4. When a forward step was initiated in response to the translation, the automatic postural responses were reduced in amplitude bilaterally in soleus and in the stance limb gastrocnemius. When present the postural response occurred at the same latency when the goal was to initiate a step as when the goal was to maintain standing.(ABSTRACT TRUNCATED AT 400 WORDS)
27
Cheresh, D. A., M. D. Pierschbacher, M. A. Herzig e K. Mujoo. "Disialogangliosides GD2 and GD3 are involved in the attachment of human melanoma and neuroblastoma cells to extracellular matrix proteins." Journal of Cell Biology 102, n. 3 (1 marzo 1986): 688–96. http://dx.doi.org/10.1083/jcb.102.3.688.
Abstract (sommario):
Human melanoma cells express relatively large amounts of the disialogangliosides GD3 and GD2 on their surface whereas neuroblastoma cells express GD2 as a major ganglioside. Monoclonal antibodies (Mabs) directed specifically to the carbohydrate moiety of GD3 and GD2 inhibit melanoma and neuroblastoma cell attachment to various substrate adhesive proteins, e.g. collagen, vitronectin, laminin, fibronectin, and a heptapeptide, glycyl-L-arginyl-glycyl-L-aspartyl-L-seryl-L-prolyl-L-cysteine, which constitutes the cell attachment site of fibronectin. Cells that are preattached to a fibronectin substrate can also be induced to detach and round up in the presence of purified anti-ganglioside Mab. Moreover, when melanoma cells that contain both GD2 and GD3 are incubated with Mabs directed to both of these molecules an additive inhibition is observed. The specificity of this inhibition is demonstrated since Mabs of various isotypes directed to either protein or carbohydrate epitopes on a number of other major melanoma or neuroblastoma cell surface antigens have no effect on cell attachment. A study of the kinetics involved in this inhibition indicates that significant effects occur during the first 5 min of cell attachment, suggesting an important role for GD2 and GD3 in the initial events of cell-substrate interactions. The role of gangliosides in cell attachment apparently does not directly involve a strong interaction with fibronectin since we could not observe any binding of radiolabeled fibronectin or fragments of the molecule known to contain the cell attachment site to melanoma gangliosides separated on thin-layer chromatograms. An alternative explanation would be that gangliosides may play a role in the electrostatic requirements for cell-substrate interactions. In this regard, controlled periodate oxidation of terminal, unsubstituted sialic acid residues on the cell surface not only specifically destroys the antigenic epitopes on GD2 and GD3 recognized by specific Mabs but also inhibits melanoma cell and neuroblastoma cell attachment. In fact, the periodate-induced ganglioside oxidation and the inhibition of cell attachment are equally dose dependent. These data suggest that cell-substratum interactions may depend in part on the electrostatic environment provided by terminal sialic acid residues of cell surface gangliosides and possibly other anionic glycoconjugates.
28
Gauba, Varun, e Jeffrey D. Hartgerink. "Self-Assembled Heterotrimeric Collagen Triple Helices Directed through Electrostatic Interactions". Journal of the American Chemical Society 129, n. 9 (marzo 2007): 2683–90. http://dx.doi.org/10.1021/ja0683640.
29
Ramirez-Arcos, S., V. Greco, H. Douglas, D. Tessier, D. Fan, J. Szeto, J. Wang e J. R. Dillon. "Conserved Glycines in the C Terminus of MinC Proteins Are Implicated in Their Functionality as Cell Division Inhibitors". Journal of Bacteriology 186, n. 9 (1 maggio 2004): 2841–55. http://dx.doi.org/10.1128/jb.186.9.2841-2855.2004.
Abstract (sommario):
ABSTRACT Alignment of 36 MinC sequences revealed four completely conserved C-terminal glycines. As MinC inhibits cytokinesis in Neisseria gonorrhoeae and Escherichia coli, the functional importance of these glycines in N. gonorrhoeae MinC (MinCNg) and E. coli MinC (MinCEc) was investigated through amino acid substitution by using site-directed mutagenesis. Each mutant was evaluated for its ability to arrest cell division and to interact with itself and MinD. In contrast to overexpression of wild-type MinC, overexpression of mutant proteins in E. coli did not induce filamentation, indicating that they lost functionality. Yeast two-hybrid studies showed that MinCEc interacts with itself and MinDEc; however, no interactions involving MinCNg were detected. Therefore, a recombinant MinC protein, with the N terminus of MinCEc and the C terminus of MinCNg, was designed to test for a MinCNg-MinDNg interaction. Each MinC mutant interacted with either MinC or MinD but not both, indicating the specificity of glycine residues for particular protein-protein interactions. Each glycine was mapped on the C-terminal surfaces (A, B, and C) of the solved Thermotoga maritima MinC structure. We found that MinCEc G161, residing in close proximity to the A surface, is involved in homodimerization, which is essential for MinC function. Glycines corresponding to MinCEc G135, G154, and G171, located within or adjacent to the B-C surface junction, are critical for MinC-MinD interactions. Circular dichroism revealed no gross structural perturbations of the mutant proteins, although the contribution of glycines to protein flexibility and stability cannot be discounted. Using molecular modeling, we propose that exposed conserved MinC glycines interact with exposed residues of the α-7 helix of MinD.
30
Benesh, Emily C., Paul M. Miller, Elise R. Pfaltzgraff, Nathan E. Grega-Larson, Hillary A. Hager, Bong Hwan Sung, Xianghu Qu, H. Scott Baldwin, Alissa M. Weaver e David M. Bader. "Bves and NDRG4 regulate directional epicardial cell migration through autocrine extracellular matrix deposition". Molecular Biology of the Cell 24, n. 22 (15 novembre 2013): 3496–510. http://dx.doi.org/10.1091/mbc.e12-07-0539.
Abstract (sommario):
Directional cell movement is universally required for tissue morphogenesis. Although it is known that cell/matrix interactions are essential for directional movement in heart development, the mechanisms governing these interactions require elucidation. Here we demonstrate that a novel protein/protein interaction between blood vessel epicardial substance (Bves) and N-myc downstream regulated gene 4 (NDRG4) is critical for regulation of epicardial cell directional movement, as disruption of this interaction randomizes migratory patterns. Our studies show that Bves/NDRG4 interaction is required for trafficking of internalized fibronectin through the “autocrine extracellular matrix (ECM) deposition” fibronectin recycling pathway. Of importance, we demonstrate that Bves/NDRG4-mediated fibronectin recycling is indeed essential for epicardial cell directional movement, thus linking these two cell processes. Finally, total internal reflectance fluorescence microscopy shows that Bves/NDRG4 interaction is required for fusion of recycling endosomes with the basal cell surface, providing a molecular mechanism of motility substrate delivery that regulates cell directional movement. This is the first evidence of a molecular function for Bves and NDRG4 proteins within broader subcellular trafficking paradigms. These data identify novel regulators of a critical vesicle-docking step required for autocrine ECM deposition and explain how Bves facilitates cell-microenvironment interactions in the regulation of epicardial cell–directed movement.
31
Abdi, Mahnaz, Paridah Md Tahir, Rawaida Liyana e Ramin Javahershenas. "A Surfactant Directed Microcrystalline Cellulose/Polyaniline Composite with Enhanced Electrochemical Properties". Molecules 23, n. 10 (26 settembre 2018): 2470. http://dx.doi.org/10.3390/molecules23102470.
Abstract (sommario):
In this study a cationic surfactant, cetyltrimethylammonium bromide (CTAB), was used as a soft template for in situ chemical polymerization of aniline on the surface of microcrystalline cellulose (MCC). The morphology of the wire-like and porous nanostructure of the resulting composite was highly dependent on the MCC and CTAB concentrations. The effect of the MCC and CTAB concentrations on the electrochemical and morphological properties of the polyaniline (PAni) nanocomposite was studied. Cyclic voltammograms of modified PAni/MCC/CTAB electrode displayed a high current response and the effect of scan rate on the current response confirmed a diffusion controlled process on the surface of the electrode that makes it suitable for sensor applications. The overlapping characteristic peaks of pure PAni and MCC caused peak broadening at 3263 cm−1 in the IR spectra of PAni/MCC/CTAB nanocomposite that revealed the interaction between NH of PAni and OH group of MCC via electrostatic interactions. The addition of MCC to PAni through chemical polymerization decreased the thermal stability of composite compared to pure PAni. Lower crystallinity was observed in the XRD diffractogram, with 2 theta values of 22.8, 16.5, and 34.6 for PAni/MCC, confirming the formation of PAni on the MCC surface.
32
Sghyar, Riham, Oussama Moussaoui, Nada Kheira Sebbar, Younesse Ait Elmachkouri, Ezaddine Irrou, Tuncer Hökelek, Joel T. Mague, Abdesslam Bentama e El Mestafa El hadrami. "Crystal structure and Hirshfeld surface analysis study of (E)-1-(4-chlorophenyl)-N-(4-ferrocenylphenyl)methanimine". Acta Crystallographica Section E Crystallographic Communications 77, n. 9 (10 agosto 2021): 875–79. http://dx.doi.org/10.1107/s2056989021008033.
Abstract (sommario):
The substituted cyclopentadienyl ring in the title molecule, [Fe(C5H5)(C18H13ClN)], is nearly coplanar with the phenyl-1-(4-chlorophenyl)methanimine substituent, with dihedral angles between the planes of the phenylene ring and the Cp and 4-(chlorophenyl)methanimine units of 7.87 (19) and 9.23 (10)°, respectively. The unsubstituted cyclopentadienyl ring is rotationally disordered, the occupancy ratio for the two orientations refined to a 0.666 (7)/0.334 (7) ratio. In the crystal, the molecules pack in `bilayers' parallel to the ab plane with the ferrocenyl groups on the outer faces and the substituents directed towards the regions between them. The ferrocenyl groups are linked by C—H...π(ring) interactions. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H...H (46.1%), H...C/C... H (35.4%) and H...Cl/Cl...H (13.8%) interactions. Thus C—H...π(ring) and van der Waals interactions are the dominant interactions in the crystal packing.
33
Sharma, Pranay, Anshuman Gogoi, Akalesh K. Verma, Antonio Frontera e Manjit K. Bhattacharyya. "Charge-assisted hydrogen bond and nitrile⋯nitrile interaction directed supramolecular associations in Cu(ii) and Mn(ii) coordination complexes: anticancer, hematotoxicity and theoretical studies". New Journal of Chemistry 44, n. 14 (2020): 5473–88. http://dx.doi.org/10.1039/d0nj00075b.
Abstract (sommario):
Charge-assisted H-bonds and nitrile⋯nitrile interactions directed assemblies in Cu(ii) and Mn(ii) complexes have been analyzed by MEP surface and NCI plot index. Anticancer activities and hematotoxictiy have been investigated.
34
Manivasagam, Vignesh K., e Ketul C. Popat. "Improved Hemocompatibility on Superhemophobic Micro–Nano-Structured Titanium Surfaces". Bioengineering 10, n. 1 (29 dicembre 2022): 43. http://dx.doi.org/10.3390/bioengineering10010043.
Abstract (sommario):
Blood-contacting titanium-based implants such as endovascular stents and heart valve casings are prone to blood clotting due to improper interactions at the surface level. In complement, the current clinical demand for cardiovascular implants is at a new apex. Hence, there is a crucial necessity to fabricate an implant with optimal mechanical properties and improved blood compatibility, while simultaneously interacting differentially with cells and other microbial agents. The present study intends to develop a superhydrophobic implant surface with the novel micro–nano topography, developed using a facile thermochemical process. The surface topography, apparent contact angle, and crystal structure are characterized on different surfaces. The hemo/blood compatibility on different surfaces is assessed by evaluating hemolysis, fibrinogen adsorption, cell adhesion and identification, thrombin generation, complement activation, and whole blood clotting kinetics. The results indicate that the super-hemo/hydrophobic micro–nano titanium surface improved hemocompatibility by significantly reducing fibrinogen adsorption, platelet adhesion, and leukocyte adhesion. Thus, the developed surface has high potential to be used as an implant. Further studies are directed towards analyzing the mechanisms causing the improved hemocompatibility of micro/nano surface features under dynamic in vitro and in vivo conditions.
35
Martínez-Cabrera, Miguel A., Mario A. Macías, Francisco Ferreira, Enrique Pandolfi, Javier Barúa e Leopoldo Suescun. "Crystal structure and Hirshfeld surface analysis of lapachol acetate 80 years after its first synthesis". Acta Crystallographica Section E Crystallographic Communications 75, n. 9 (19 agosto 2019): 1362–66. http://dx.doi.org/10.1107/s2056989019011393.
Abstract (sommario):
Lapachol acetate [systematic name: 3-(3-methylbut-2-enyl)-1,4-dioxonaphthalen-2-yl acetate], C17H16O4, was prepared using a modified high-yield procedure and its crystal structure is reported for the first time 80 years after its first synthesis. The full spectroscopic characterization of the molecule is reported. The molecular conformation shows little difference with other lapachol derivatives and lapachol itself. The packing is directed by intermolecular π–π and C—H...O interactions, as described by Hirshfeld surface analysis. The former interactions make the largest contributions to the total packing energy in a ratio of 2:1 with respect to the latter.
36
Seppänen, Allan. "Collagen XVII: A Shared Antigen in Neurodermatological Interactions?" Clinical and Developmental Immunology 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/240570.
Abstract (sommario):
Collagen XVII is a nonfibril-forming transmembrane collagen, which functions as both a matrix protein and a cell-surface receptor. It is particularly copious in the skin, where it is known to be a structural component of hemidesmosomes. In addition, collagen XVII has been found to be present in the central nervous system, thus offering an explanation for the statistical association between bullous pemphigoid, in which autoimmunity is directed against dermal collagen XVII, and neurological diseases. In support of the hypothesis that collagen XVII serves as a shared antigen mediating an immune response between skin and brain, research on animal and human tissue, as well as numerous epidemiological and case studies, is presented.
37
Brasz, C. Frederik, Craig B. Arnold, Howard A. Stone e John R. Lister. "Early-time free-surface flow driven by a deforming boundary". Journal of Fluid Mechanics 767 (24 febbraio 2015): 811–41. http://dx.doi.org/10.1017/jfm.2015.74.
Abstract (sommario):
AbstractWhen a solid boundary deforms rapidly into a quiescent liquid layer, a flow is induced that can lead to jet formation. An asymptotic analytical solution is presented for this flow, driven by a solid boundary deforming with dimensionless vertical velocity $V_{b}(x,t)={\it\epsilon}(1+\cos x)\,f(t)$, where the amplitude ${\it\epsilon}$ is small relative to the wavelength and the time dependence $f(t)$ approaches 0 for large $t$. Initially, the flow is directed outwards from the crest of the deformation and slows with the slowing of the boundary motion. A domain-perturbation method is used to reveal that, when the boundary stops moving, nonlinear interactions with the free surface leave a remnant momentum directed back towards the crest, and this momentum can be a precursor to jet formation. This scenario arises in a laser-induced printing technique in which an expanding blister imparts momentum into a liquid film to form a jet. The analysis provides insight into the physics underlying the interaction between the deforming boundary and free surface, in particular, the dependence of the remnant flow on the thickness of the liquid layer and the deformation amplitude and wavelength. Numerical simulations are used to show the range of validity of the analytical results, and the domain-perturbation solution is extended to an axisymmetric domain with a Gaussian boundary deformation to compare with previous numerical simulations of blister-actuated laser-induced forward transfer.
38
Seguin, M. C., W. R. Ballou e C. A. Nacy. "Interactions of Plasmodium berghei sporozoites and murine Kupffer cells in vitro." Journal of Immunology 143, n. 5 (1 settembre 1989): 1716–22. http://dx.doi.org/10.4049/jimmunol.143.5.1716.
Abstract (sommario):
Abstract Malaria sporozoites must leave the bloodstream and cross a layer of sinusoidal lining cells in order to infect hepatocytes and undergo exoerythrocytic schizogony. To determine whether Kupffer cells (KC) derived from this layer interact with sporozoites, murine KC were isolated from perfused livers of BALB/cJ mice and incubated in vitro with Plasmodium berghei sporozoites. Isolated KC had characteristic macrophage surface Ag and were phagocytic, ingesting both latex particles and Leishmania major amastigotes. In the absence of immune serum, sporozoites associated with fewer than 10% of these KC. By 30 min, 10% of the cell-associated sporozoites were completely ingested, 30% were in the process of being ingested, and 60% were attached to the surface of the cells. Opsonization of sporozoites with monoclonal or polyclonal antibodies directed against P. berghei circumsporozoite protein markedly enhanced sporozoite association with KC. Up to 40% of cells exposed to opsonized sporozoites had parasites inside or attached to their surfaces. Sporozoites attached to or ingested by KC were uniformly destroyed within 240 min in all cultures; there was no evidence of conversion of sporozoites to the exoerythrocytic stage within KC by light microscopy, and there was no evidence of residual sporozoites, either inside or outside of cells, by either light or electron microscopy. These data suggest that under nonimmune conditions, KC play a minor role in resistance to infection by malaria sporozoites. However, when sporozoites are opsonized by circumsporozoite antibodies, phagocytosis by KC may be an important immune mechanism that prevents parasitization of hepatocytes.
39
Litvinov, Rustem I., Marco Mravic, Hua Zhu, John W. Weisel, William F. DeGrado e Joel S. Bennett. "Unique transmembrane domain interactions differentially modulate integrin αvβ3 and αIIbβ3 function". Proceedings of the National Academy of Sciences 116, n. 25 (3 giugno 2019): 12295–300. http://dx.doi.org/10.1073/pnas.1904867116.
Abstract (sommario):
Lateral transmembrane (TM) helix–helix interactions between single-span membrane proteins play an important role in the assembly and signaling of many cell-surface receptors. Often, these helices contain two highly conserved yet distinct interaction motifs, arranged such that the motifs cannot be engaged simultaneously. However, there is sparse experimental evidence that dual-engagement mechanisms play a role in biological signaling. Here, we investigate the function of the two conserved interaction motifs in the TM domain of the integrin β3-subunit. The first motif uses reciprocating “large-large-small” amino acid packing to mediate the interaction of the β3 and αIIb TM domains and maintain the inactive resting conformation of the platelet integrin αIIbβ3. The second motif, S-x3-A-x3-I, is a variant of the classical “G-x3-G” motif. Using site-directed mutagenesis, optical trap-based force spectroscopy, and molecular modeling, we show that S-x3-A-x3-I does not engage αIIb but rather mediates the interaction of the β3 TM domain with the TM domain of the αv-subunit of the integrin αvβ3. Like αIIbβ3, αvβ3 on circulating platelets is inactive, and in the absence of platelet stimulation is unable to interact with components of the subendothelial matrix. However, disrupting any residue in the β3 S-x3-A-x3-I motif by site-directed mutations is sufficient to induce αvβ3 binding to the αvβ3 ligand osteopontin and to the monoclonal antibody WOW-1. Thus, the β3-integrin TM domain is able to engage in two mutually exclusive interactions that produce alternate α-subunit pairing, creating two integrins with distinct biological functions.
40
Saitô, H., R. Kawaminami, M. Tanio, T. Arakawa, S. Yamaguchi e S. Tuzi. "Dynamic aspect of bacteriorhodopsin as viewed from13C NMR: Conformational elucidation, surface dynamics and information transfer from the surface to inner residues". Spectroscopy 16, n. 3-4 (2002): 107–20. http://dx.doi.org/10.1155/2002/190968.
Abstract (sommario):
We demonstrate here how dynamic as well as conformational features of bacteriorhodopsin (bR) in purple membrane (PM) as a typical membrane protein are revealed by extensive13C NMR studies on [3-13C]-, [2-13C]-, [1-13C]Ala or [1-13C]Val-labeled bR and a variety of site-directed mutants. A number of13C NMR peaks were well-resolved for [3‒13C]Ala‒ and [1-13C]Val-bR under the condition of fully hydrated PM at ambient temperature and assigned to individual amino-acid residues, initially by regio-specific manner with reference to the data of the conformation-dependent displacements of peaks from model polypeptides and subsequently by site-specific manner with reference to the specifically reduced peak-intensities of site-directed mutant as compared with those of wild type. It is noticeable that the revealed bR structure at ambient temperature by13C NMR is not static as anticipated from the data of diffraction studies at cryo-temperature but is dynamically heterogeneous undergoing motional fluctuations with various frequencies (102–108Hz) depending upon the domains of interest. We further applied this approach to reveal how charged state of surface residues, especially at the side-chain of exracellular Glu residues (Glu 194 and 204), could be transmitted to the inner part of the helices such as Ala 53, 84, and 215 to alter their local conformations of transmembrane helices near at the Schiff base through side-chain interactions. We also analyzed how information of the protonation at Asp 85 from helix C is initially transmitted to helices B (Val 49) and G (Val 213) though modified helix‒helix interactions through the side-chains of Arg 82.
41
Alekseenko, Irina V., Igor P. Chernov, Sergei V. Kostrov e Eugene D. Sverdlov. "Are Synapse-Like Structures a Possible Way for Crosstalk of Cancer with Its Microenvironment?" Cancers 12, n. 4 (27 marzo 2020): 806. http://dx.doi.org/10.3390/cancers12040806.
Abstract (sommario):
The failure of therapies directed at targets within cancer cells highlight the necessity for a paradigm change in cancer therapy. The attention of researchers has shifted towards the disruption of cancer cell interactions with the tumor microenvironment. A typical example of such a disruption is the immune checkpoint cancer therapy that disrupts interactions between the immune and the cancer cells. The interaction of cancer antigens with T cells occurs in the immunological synapses. This is characterized by several special features, i.e., the proximity of the immune cells and their target cells, strong intercellular adhesion, and secretion of signaling cytokines into the intercellular cleft. Earlier, we hypothesized that the cancer-associated fibroblasts interacting with cancer cells through a synapse-like adhesion might play an important role in cancer tumors. Studies of the interactions between cancer cells and cancer-associated fibroblasts showed that their clusterization on the membrane surface determined their strength and specificity. The hundreds of interacting pairs are involved in the binding that may indicate the formation of synapse-like structures. These interactions may be responsible for successful metastasis of cancer cells, and their identification and disruption may open new therapeutic possibilities.
42
Adelman, B., A. Rizk e E. Hanners. "Plasminogen interactions with platelets in plasma". Blood 72, n. 5 (1 novembre 1988): 1530–35. http://dx.doi.org/10.1182/blood.v72.5.1530.1530.
Abstract (sommario):
Abstract In this report we used a fluorescent flow cytometry-based assay to examine plasminogen binding to platelets in plasma. Our data indicate that platelets activated in platelet-rich plasma (PRP) by adenosine-5′- diphosphate (ADP) or thrombin bind plasminogen to their surface. Fab fragments of the monoclonal antibody LJ-CP8 that are directed against the fibrinogen binding site on the glycoprotein (GP) IIb-IIIa complex inhibit both plasminogen and fibrinogen binding to ADP-stimulated platelets as does 5 mmol/L EDTA. Platelet aggregation and plasminogen and fibrinogen binding are also concurrently inhibited by the Gly-Arg- Asp (RGD) analogue Gly-Arg-Gly-Asp-Ser (GRGDS) when it is added to PRP before ADP stimulation. The scrambled peptide analogue SDGRG has no effect. The monoclonal antibody 6D1, directed against the von Willebrand factor binding site on GPIb, has no effect on plasminogen- platelet binding, nor does antithrombospondin antibody. epsilon- Aminocaproic acid (EACA), however, inhibits plasminogen binding to ADP- activated platelets. These data indicate that plasminogen binds to platelets activated in plasma, that binding occurs on platelet GPIIb/IIIa, and that binding may be mediated via plasminogen association with fibrinogen via lysine binding domains. Finally, we found both plasminogen and fibrinogen on resting platelets in PRP and demonstrated that they are equally displaced by EDTA, LJ-CP8, and 10E5 (an additional anti-GPIIb/IIIa monoclonal antibody). Plasminogen is also equally displaced by EACA. These data suggest that plasminogen is also bound to GPIIb/IIIa on resting platelets, possibly also via interaction with fibrinogen.
43
Adelman, B., A. Rizk e E. Hanners. "Plasminogen interactions with platelets in plasma". Blood 72, n. 5 (1 novembre 1988): 1530–35. http://dx.doi.org/10.1182/blood.v72.5.1530.bloodjournal7251530.
Abstract (sommario):
In this report we used a fluorescent flow cytometry-based assay to examine plasminogen binding to platelets in plasma. Our data indicate that platelets activated in platelet-rich plasma (PRP) by adenosine-5′- diphosphate (ADP) or thrombin bind plasminogen to their surface. Fab fragments of the monoclonal antibody LJ-CP8 that are directed against the fibrinogen binding site on the glycoprotein (GP) IIb-IIIa complex inhibit both plasminogen and fibrinogen binding to ADP-stimulated platelets as does 5 mmol/L EDTA. Platelet aggregation and plasminogen and fibrinogen binding are also concurrently inhibited by the Gly-Arg- Asp (RGD) analogue Gly-Arg-Gly-Asp-Ser (GRGDS) when it is added to PRP before ADP stimulation. The scrambled peptide analogue SDGRG has no effect. The monoclonal antibody 6D1, directed against the von Willebrand factor binding site on GPIb, has no effect on plasminogen- platelet binding, nor does antithrombospondin antibody. epsilon- Aminocaproic acid (EACA), however, inhibits plasminogen binding to ADP- activated platelets. These data indicate that plasminogen binds to platelets activated in plasma, that binding occurs on platelet GPIIb/IIIa, and that binding may be mediated via plasminogen association with fibrinogen via lysine binding domains. Finally, we found both plasminogen and fibrinogen on resting platelets in PRP and demonstrated that they are equally displaced by EDTA, LJ-CP8, and 10E5 (an additional anti-GPIIb/IIIa monoclonal antibody). Plasminogen is also equally displaced by EACA. These data suggest that plasminogen is also bound to GPIIb/IIIa on resting platelets, possibly also via interaction with fibrinogen.
44
Hjelm, Linnea Charlotta, Hanna Lindberg, Stefan Ståhl e John Löfblom. "Construction and Validation of a New Naïve Sequestrin Library for Directed Evolution of Binders against Aggregation-Prone Peptides". International Journal of Molecular Sciences 24, n. 1 (3 gennaio 2023): 836. http://dx.doi.org/10.3390/ijms24010836.
Abstract (sommario):
Affibody molecules are small affinity proteins that have excellent properties for many different applications, ranging from biotechnology to diagnostics and therapy. The relatively flat binding surface is typically resulting in high affinity and specificity when developing binding reagents for globular target proteins. For smaller unstructured peptides, the paratope of affibody molecules makes it more challenging to achieve a sufficiently large binding surface for high-affinity interactions. Here, we describe the development of a new type of protein scaffold based on a dimeric form of affibodies with a secondary structure content and mode of binding that is distinct from conventional affibody molecules. The interaction is characterized by encapsulation of the target peptide in a tunnel-like cavity upon binding. The new scaffold was used for construction of a high-complexity phage-displayed library and selections from the library against the amyloid beta peptide resulted in identification of high-affinity binders that effectively inhibited amyloid aggregation.
45
Carulli, Sonia, Konrad Beck, Guila Dayan, Sophie Boulesteix, Hugues Lortat-Jacob e Patricia Rousselle. "Cell Surface Proteoglycans Syndecan-1 and -4 Bind Overlapping but Distinct Sites in Laminin α3 LG45 Protein Domain". Journal of Biological Chemistry 287, n. 15 (20 febbraio 2012): 12204–16. http://dx.doi.org/10.1074/jbc.m111.300061.
Abstract (sommario):
Keratinocyte migration during epidermal repair depends on interactions between cellular heparan sulfate proteoglycan receptors, syndecan-1 and -4, and the C-terminal globular domains (LG45) of the extracellular matrix protein laminin 332. This study investigates the molecular basis of the binding specificity of the syndecan-1 and -4 receptors expressed by human keratinocytes. We used site-directed mutagenesis to alter a recombinant LG45 protein by substituting the most critical basic residues with glutamine. All proteins were expressed in mammalian cells, purified, and characterized biochemically. We used in vitro binding assays, including surface plasmon resonance, to examine interactions between mutated LG45 and heparan sulfates, syndecan-1 and -4. We identify a major heparin binding domain on the outer edge of a β-strand of LG45 surrounded by a track of converging low affinity residues. This domain harbors distinctive syndecan-1 and -4 binding-specific sequences. This is the first study to demonstrate a binding specificity of two proteoglycans produced by a single cell type. In addition, we found that although syndecan-1 interacts exclusively through its glycosaminoglycan chains, syndecan-4 binding relies on both its core protein and its heparan sulfate chains. These results suggest that LG45 may trigger different signals toward keratinocytes depending on its interaction with syndecan-1 or -4.
46
Tahara, Kazukuni, Keisuke Katayama, Matthew Oliver Blunt, Kohei Iritani, Steven De Feyter e Yoshito Tobe. "Functionalized Surface-Confined Pores: Guest Binding Directed by Lateral Noncovalent Interactions at the Solid–Liquid Interface". ACS Nano 8, n. 8 (8 agosto 2014): 8683–94. http://dx.doi.org/10.1021/nn503815q.
47
SHEPHERD, Craig M., Hans J. VOGEL e D. Peter TIELEMAN. "Interactions of the designed antimicrobial peptide MB21 and truncated dermaseptin S3 with lipid bilayers: molecular-dynamics simulations". Biochemical Journal 370, n. 1 (15 febbraio 2003): 233–43. http://dx.doi.org/10.1042/bj20021255.
Abstract (sommario):
Molecular-dynamics simulations covering 30ns of both a natural and a synthetic antimicrobial peptide in the presence of a zwitterionic lipid bilayer were performed. In both simulations, copies of the peptides were placed in an α-helical conformation on either side of the bilayer about 10Å (1Å = 0.1nm) from the interface, with either the hydrophobic or the positively charged face of the helix directed toward the bilayer surface. The degree of peptide—lipid interaction was dependent on the starting configuration: surface binding and subsequent penetration of the bilayer was observed for the hydrophobically oriented peptides, while the charge-oriented peptides demonstrated at most partial surface binding. Aromatic residues near the N-termini of the peptides appear to play an important role in driving peptide—lipid interactions. A correlation between the extent of peptide—lipid interactions and helical stability was observed in the simulations. Insertion of the peptides into the bilayer caused a dramatic increase in the lateral area per lipid and decrease in the bilayer thickness, resulting in substantial disordering of the lipid chains. Results from the simulations are consistent with early stages of proposed mechanisms for the lytic activity of antimicrobial peptides. In addition to these ‘free’ simulations, 25ns simulations were carried out with the peptides constrained at three different distances relative to the bilayer interface. The constraint forces are in agreement with the extent of peptide—bilayer insertion observed in the free simulations.
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Tailor, Chetankumar S., Ali Nouri e David Kabat. "A Comprehensive Approach to Mapping the Interacting Surfaces of Murine Amphotropic and Feline Subgroup B Leukemia Viruses with Their Cell Surface Receptors". Journal of Virology 74, n. 1 (1 gennaio 2000): 237–44. http://dx.doi.org/10.1128/jvi.74.1.237-244.2000.
Abstract (sommario):
ABSTRACT Because mutations in envelope glycoproteins of retroviruses or in their cell surface receptors can eliminate function by multiple mechanisms, it has been difficult to unambiguously identify sites for their interactions by site-directed mutagenesis. Recently, we developed a gain-of-function approach to overcome this problem. Our strategy relies on the fact that feline leukemia virus subgroup B (FeLV-B) and amphotropic murine leukemia virus (A-MLV) have closely related gp70 surface envelope glycoproteins and use related Na+-dependent phosphate symporters, Pit1 and Pit2, respectively, as their receptors. We previously observed that FeLV-B/A-MLV envelope glycoprotein chimeras spliced between the variable regions VRA and VRB were unable to use Pit1 or Pit2 as a receptor but could efficiently use specific Pit1/Pit2 chimeras. The latter study suggested that the VRA of A-MLV and FeLV-B functionally interact with the presumptive extracellular loops 4 and 5 (ECL4 and -5) of their respective receptors, whereas VRB interacts with ECL2. We also found that FeLV-B gp70 residues F60 and P61 and A-MLV residues Y60 and V61 in the first disulfide-bonded loop of VRA were important for functional interaction with the receptor's ECL4 or -5. We have now extended this approach to identify additional VRA and VRB residues that are involved in receptor recognition. Our studies imply that FeLV-B VRA residues F60 and P61 interact with the Pit1 ECL5 region, whereas VRA residues 66 to 78 interact with Pit1 ECL4. Correspondingly, A-MLV VRA residues Y60 and V61 interact with the Pit2 ECL5 region, whereas residues 66 to 78 interact with Pit2 ECL4. Similar studies that focused on the gp70 VRB implicated residues 129 to 139 as contributing to specific interactions with the receptor ECL2. These results identify three regions of gp70 that interact in a specific manner with distinct portions of their receptors, thereby providing a map of the functionally interacting surfaces.
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Gallington, Leighanne C., In Soo Kim, Wei-Guang Liu, Andrey A. Yakovenko, Ana E. Platero-Prats, Zhanyong Li, Timothy C. Wang et al. "Regioselective Atomic Layer Deposition in Metal–Organic Frameworks Directed by Dispersion Interactions". Journal of the American Chemical Society 138, n. 41 (10 ottobre 2016): 13513–16. http://dx.doi.org/10.1021/jacs.6b08711.
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Gole, James L., e William Laminack. "Nanostructure-directed chemical sensing: The IHSAB principle and the dynamics of acid/base-interface interaction". Beilstein Journal of Nanotechnology 4 (14 gennaio 2013): 20–31. http://dx.doi.org/10.3762/bjnano.4.3.
Abstract (sommario):
Nanostructure-decorated n-type semiconductor interfaces are studied in order to develop chemical sensing with nanostructured materials. We couple the tenets of acid/base chemistry with the majority charge carriers of an extrinsic semiconductor. Nanostructured islands are deposited in a process that does not require self-assembly in order to direct a dominant electron-transduction process that forms the basis for reversible chemical sensing in the absence of chemical-bond formation. Gaseous analyte interactions on a metal-oxide-decorated n-type porous silicon interface show a dynamic electron transduction to and from the interface depending upon the relative strength of the gas and metal oxides. The dynamic interaction of NO with TiO2, SnO2, NiO, Cu x O, and Au x O (x >> 1), in order of decreasing acidity, demonstrates this effect. Interactions with the metal-oxide-decorated interface can be modified by the in situ nitridation of the oxide nanoparticles, enhancing the basicity of the decorated interface. This process changes the interaction of the interface with the analyte. The observed change to the more basic oxinitrides does not represent a simple increase in surface basicity but appears to involve a change in molecular electronic structure, which is well explained by using the recently developed IHSAB model. The optical pumping of a TiO2 and TiO2− x N x decorated interface demonstrates a significant enhancement in the ability to sense NH3 and NO2. Comparisons to traditional metal-oxide sensors are also discussed.