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Molecular Recognition (molecular + recognition)
Terms modified by Molecular Recognition Selected AbstractsA Theoretical ab initio Study of the Capacity of Several Binding Units for the Molecular Recognition of AnionsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 1 2005Carolina Garau Abstract Noncovalent bonding between anions and the ,-cloud of electron-deficient aromatic rings has recently attracted considerable attention. Complexes of bromide with different electron-deficient aromatic rings and with other binding units based on hydrogen bonding (urea, thiourea and squaramide) have been studied and compared using high level B3LYP/6-31++G** ab initio and Molecular Interaction Potential with polarization (MIPp) calculations. Our findings reveal that electron-deficient aromatic rings are excellent candidates for constructing anion receptors and that the interaction strength can be modulated by the nature of the ring. Supporting experimental evidence has been obtained from X-ray structures retrieved from the Cambridge Structural Database. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Molecular Recognition by Synthetic Multifunctional Pores in Practice: Are Structural Studies Really Helpful?,ADVANCED FUNCTIONAL MATERIALS, Issue 2 2006Y. Baudry Abstract This account summarizes five years of research devoted to the development of the concept of synthetic multifunctional pores. The objective is to complement a comprehensive graphical summary of molecular recognition with a survey of structural studies on the same topic. The relevance of the latter for research focusing on creation and application of supramolecular functional materials is discussed briefly in a subjective manner. [source] Molecular Recognition of a Peptide by the Nickel(II) Complex of 1,4,7,10-Tetraazacyclododecane-2,9-dioneHELVETICA CHIMICA ACTA, Issue 3 2003Jian Gao The nickel(II) complex of the macrocycle 1,4,7,10-tetraazacyclododecane-2,9-dione (dota) was found to be efficient in the recognition of the dipeptide, glycyl-glycine (Gly-Gly) in aqueous solution. This (dota)NiII complex serves as a targeting molecule to form a stable ternary complex with the dipeptide at pH,8.3 in aqueous solution. The recognition constant (log K=19.20) and the recognition mechanism were investigated based on the potentiometric method. The single-crystal of a six-coordinated (dota)2NiII complex is also reported. [source] Chemical Interactions at Metal/Molecule Interfaces in Molecular Junctions,A Pathway Towards Molecular Recognition,ADVANCED MATERIALS, Issue 3 2009Mila Manolova A 4-aminothiophenol self-assembled monolayer (see image) is prepared on top of a Au(111) crystal, which is subsequently metallized by a nearly closed Pd overlayer of monoatomic height. Analysis of its structural setup and electronic properties reveals that the monolayer consists of a minimum of two molecular layers, and strong chemical interactions between the metal overlayer and the amino groups are found to play a decisive role in determining the overall electronic, and thus the transport properties, of the layer/metal contact. [source] Past, present and future of atomic force microscopy in life sciences and medicineJOURNAL OF MOLECULAR RECOGNITION, Issue 6 2007Pierre Parot Abstract To introduce this special issue of the Journal of Molecular Recognition dedicated to the applications of atomic force microscopy (AFM) in life sciences, this paper presents a short summary of the history of AFM in biology. Based on contributions from the first international conference of AFM in biological sciences and medicine (AFM BioMed Barcelona, 19,21 April 2007), we present and discuss recent progress made using AFM for studying cells and cellular interactions, probing single molecules, imaging biosurfaces at high resolution and investigating model membranes and their interactions. Future prospects in these different fields are also highlighted. Copyright © 2007 John Wiley & Sons, Ltd. [source] Molecular Recognition in Partially Folded States of a Transporter Protein: Temperature-dependent Specificity of Bovine Serum AlbuminPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2008Debapriya Banerjee The specificity of molecular recognition of a transporter protein bovine serum albumin (BSA) in its different partially folded states has been studied. In order to avoid complications due to chemical denaturation, we have prepared thermally induced partially folded states of the protein. The partially folded states have been structurally characterized by circular dichroism and differential thermal analysis techniques. The change in the globular structure of the protein as a consequence of thermal unfolding has also been characterized by dynamic light scattering. Steady state, picosecond-resolved fluorescence and polarization gated spectroscopies on the ligands (DCM, LDS 750) in the protein reveal the dynamics of the binding sites and the specificity of ligand binding of BSA. Picosecond resolved Förster resonance energy transfer studies on the donor DCM and acceptor LDS 750 confirm that the specificity of ligand binding in the binding site is maintained up to 70°C. At 75°C, the protein loses its specificity of recognition at the aforesaid site. [source] Molecular Recognition of a Transition State,ANGEWANDTE CHEMIE, Issue 28 2010Xiaoguang Bao Dr. Drin schneller als draußen: Die Konformationsumkehr von Cyclohexan verläuft im Innern von molekularen Körben (siehe Bild) schneller als in freiem Lösungsmittel oder in einem Vakuum. Grund ist eine günstigere nichtkovalente Bindung, und damit eine Stabilisierung der Übergangszustands der eingeschlossenen Verbindung. [source] Probing the Molecular Recognition of a DNA,RNA Hybrid Duplex,ANGEWANDTE CHEMIE, Issue 18 2010Richard Verquerer und verquerer! Ein Biarylpyrimidin-Ligand (siehe Bild: N,blau, H,cyan, S,gelb) zeigt eine ausgeprägte Struktur- und Sequenzselektivität für den Poly(dA),Poly(rU)-Hybriddoppelstrang. Bei einer unerwarteten Bindungsform kann dieser Ligand durch Interkalation mit zehn Basenpaaren wechselwirken. Eine starke Korrelation zwischen Hybriddoppelstrang- und DNA-Tripelstrang-Bindung zeigt neue Wege des Ligandendesigns auf. [source] Book Review: Protein,Ligand Interactions,From Molecular Recognition to Drug Design Methods.CHEMBIOCHEM, Issue 11 2003Edited by Hans-Joachim Böhm, Gisbert Schneider No abstract is available for this article. [source] Molecular Recognition of Organic Guest Vapor by Solid Adamantylcalix[4]arene.CHEMINFORM, Issue 33 2004V. V. Gorbatchuk No abstract is available for this article. [source] The Structure of the Sugar Residue in Glycated Human Serum Albumin and Its Molecular Recognition by Phenylboronate.CHEMINFORM, Issue 32 2003Jan Rohovec No abstract is available for this article. [source] ChemInform Abstract: Design of Homooxacalix[3]arene,Porphyrin Heterocapsules which Provide Novel Cavities for Molecular Recognition.CHEMINFORM, Issue 6 2001Atsushi Ikeda Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Self-Assembly of Calix[6]arene,Diazapyrenium Pseudorotaxanes: Interplay of Molecular Recognition and Ion-Pairing EffectsCHEMISTRY - A EUROPEAN JOURNAL, Issue 11 2010Monica Semeraro Abstract The calix[6]arene wheel CX forms pseudorotaxane species with the diazapyrenium-based axle 1,2PF6 in CH2Cl2 solution. The macrocyclic component is a heteroditopic receptor, which can complex the electron-acceptor moiety of the axle inside its cavity and the counterions with the ureidic groups on the upper rim. The self-assembled supramolecular species is a complex structure, which involves three components,the wheel, the axle and its counterions,that can mutually interact and affect. The stoichiometry of the resulting supramolecular complex depends on the nature and concentration of the counterions. Namely, it is observed that in dilute solution and with low-coordinating anions the axle takes two wheels, whereas with highly coordinating anions or in concentrated solutions the complex has a 1:1 stoichiometry. [source] Molecular Recognition and Crystal Energy Landscapes: An X-ray and Computational Study of Caffeine and Other MethylxanthinesCHEMISTRY - A EUROPEAN JOURNAL, Issue 1 2005Lucia Carlucci Dr. Abstract We introduce a new approach to crystal-packing analysis, based on the study of mutual recognition modes of entire molecules or of molecular moieties, rather than a search for selected atom,atom contacts, and on the study of crystal energy landscapes over many computer-generated polymorphs, rather than a quest for the one most stable crystal structure. The computational tools for this task are a polymorph generator and the PIXEL density sums method for the calculation of intermolecular energies. From this perspective, the molecular recognition, crystal packing, and solid-state phase behavior of caffeine and several methylxanthines (purine-2,6-diones) have been analyzed. Many possible crystal structures for anhydrous caffeine have been generated by computer simulation, and the most stable among them is a thermodynamic, ordered equivalent of the disordered phase, revealed by powder X-ray crystallography. Molecular recognition energies between two caffeine molecules or between caffeine and water have been calculated, and the results reveal the largely predominant mode to be the stacking of parallel caffeine molecules, an intermediately favorable caffeine,water interaction, and many other equivalent energy minima for lateral interactions of much less stabilization power. This last indetermination helps to explain why caffeine does not crystallize easily into an ordered anhydrous structure. In contrast, the mono- and dimethylxanthines (theophylline, theobromine, and the 1,7-isomer, for which we present a single-crystal X-ray study and a lattice energy landscape) do crystallize in anhydrous form thanks to the formation of lateral hydrogen bonds. [source] Foreword Preface to the JMR Special Issue on ,Dynamic Aspects of Molecular Recognition'JOURNAL OF MOLECULAR RECOGNITION, Issue 2 2010Olivier Michielin No abstract is available for this article. [source] Molecular recognition of sugars by lanthanide (III) complexes of a conjugate of N, N -bis[2-[bis[2-(1, 1-dimethylethoxy)-2-oxoethyl]amino]ethyl]glycine and phenylboronic acidCONTRAST MEDIA & MOLECULAR IMAGING, Issue 4 2007Elisa Battistini Abstract A novel conjugate of phenylboronic acid and an Ln(DTPA) derivative, in which the central acetate pendant arm was replaced by the methylamide of L -lysine, was synthesized and characterized. The results of a fit of variable 17O NMR data and a 1H NMRD profile show that the water residence lifetime of the Gd(III) complex (150,ns) is shorter than that of the parent compound Gd(DTPA)2, (303,ns). Furthermore, the data suggest that several water molecules in the second coordination sphere of Gd(III) contribute to the relaxivity of the conjugate. The Ln(III) complexes of this conjugate are highly suitable for molecular recognition of sugars. The interaction with various sugars was investigated by 11B NMR spectroscopy. Thanks to the thiourea function that links the phenylboronic acid targeting vector with the DTPA derivative, the interactions are stronger than that of phenylboronic acid itself. In particular, the interaction with N -propylfructosamine, a model for the glucose residue in glycated human serum albumin (HSA), is very strong. Unfortunately, the complex also shows a rather strong interaction with hexose-free HSA (KA,=,705,±,300). Copyright © 2007 John Wiley & Sons, Ltd. [source] Hexaazamacrocycle Containing Pyridine and Its Dicopper Complex as Receptors for Dicarboxylate AnionsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 22 2005Feng Li Abstract The host,guest binding interactions of the hexaazamacrocycle [26]py2N4, in its tetraprotonated form H4[26]py2N44+ as well as in its dicopper(II) complex [Cu2([26]py2N4)(H2O)4]4+, with dicarboxylate anions of different stereoelectronicrequirements, such as oxalate (ox2,), malonate (mal2,), succinate (suc2,), fumarate (fu2,) and maleate (ma2,), were evaluated. The association constants were determined using potentiometric methods in aqueous solution, at 298.0 K and 0.10 mol·dm,3 KCl. These values for the tetraprotonated ditopic receptor with the dicarboxylate anions revealed that the main species in solution corresponds to the formation of {H4[26]py2N4(A)}2+ (pH , 4,9), A being the substrate anion. The values determined are not especially high, but the receptor exhibits selectivity for the malonate anion. The study of the cascade complexes revealed several species in solution, involving mononuclear and dinuclear complexes, mainly protonated and hydrolysed species, as well as the expected complexes [Cu2([26]py2N4)(A)(H2O)x]2+ or [Cu2([26]py2N4)(A)2(H2O)y]. Ox2, and mal2, form cascade complexes with only one anion, which will necessarily bridge the two copper atoms because of the symmetrical arrangement of the dinuclear complex. The two other studied anions, suc2, and ma2,, form species involving two substrate anions, although species with only one suc2, anion were also found. UV/Vis and EPR spectroscopy have shown that the dicopper complex can operate as a sensor to detect and quantitatively determine oxalate spectrophotometrically because of the red shift of the maximum of the visible band observed by addition of ox2, to an aqueous solution of the dinuclear copper complex. However the selectivity of [Cu2([26]py2N4)(H2O)4]4+ as a receptor for ox2, in the studied series is not sufficiently high to detect ox2, spectrophotometrically in the presence of the other anions. Molecular dynamics simulations indicated that the H4[26]py2N44+ receptor provides a large and flexible cavity to accommodate the studied anions. Molecular recognition is based in electrostatic interactions rather than in multiple hydrogen-bonding interactions acting cooperatively. By contrast, the [Cu2([26]py2N4)]4+ receptor has a well-shaped cavity with adequate size to uptake these anions as bridging ligands with formation of four Cu,O bonds. The ox2, anion is encapsulated within the cascade complex while the remaining anions are located above the N6 macrocyclic plane, suggesting a selective coordination behaviour of this receptor. In spite of our molecular simulation being carried out in gas phase, the modelling results are consistent with the solution studies. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Mechanism of Selective and Unselective Enclathration by a Host Compound Possessing Open, Flexible Host FrameworksEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 13 2003Kazunori Nakano Abstract Molecular recognition of o -, m -, and p -xylenes (oX, mX, and pX) through enclathration of cholic acid (CA) is described. All of the xylenes give lattice inclusion crystals with CA, and crystallographic studies reveal that they are included in different open host frameworks. In particular, oX has two polymorphs, depending on the recrystallization temperatures. Competitive recrystallization from mixtures of xylenes resulted in selective enclathrations and the formation of racemic mixed crystals. In the presence of an equimolar amount of oX, CA selectively includes mX or pX in the host frameworks, which are identical to those obtained from the pure mX or pX, respectively. The low affinity of oX is explained in terms of a lower stability of CA·oX than of the other two complexes, as judged from the low PCcavity, the volume ratio of the guest compound to the host cavity. Meanwhile, mixtures of mX and pX yield inclusion crystals that accommodate both of the guests. These have the same open host framework as obtained from pure mX, and the guest components are disordered statically in the host cavity. The ratios of the xylene mixtures in the single crystals are similar to those in the original recrystallization mixtures, and also in the bulk crystals, indicating that CA forms mixed crystals of mX and pX. This non-selectivity is attributed to the similar stabilities of CA·mX and CA·pX, according to the moderate PCcavity. The inclusion behavior of CA from mixtures of xylenes is quite similar to chiral recognition by diastereomer-salt methods. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Supramolecular Architectures: Selective Formation of Bi-Component Arrays Through H-Bonding of Multivalent Molecular Modules (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 8 2009Mater. Molecular recognition occurs at dynamic interfaces too! The cover shows a donor,acceptor,donor hydrogen-bond moiety, incorporated in a tailor-made monovalent molecular module (in blue), that is able to recognize both complementary monovalent (in red) and tetravalent (in green) molecular modules at interfaces. This finding, described by P. Samori and co-workers on page 1207, paves the way towards the formation of robust multicomponent 2D functional nanostructures with tunable size and geometries. [source] Molecular recognition: Identifying compounds and their targetsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue S37 2001Prabhavathi B. Fernandes Ph.D. Abstract As a result of gene sequencing and proteomic efforts, thousands of new genes and proteins are now available as potential drug targets. The milieu of these proteins is complex and interactive; thousands of proteins activate, inhibit, and control each other's actions. The effect of blocking or activating a protein in a cell is far-reaching, and can affect whole, as well as adjacent pathways. This network of pathways is dynamic and a cellular response can change depending on the stimulus. In this section, the identification and role of individual proteins within the context of networked pathways, and the regulation of the activity of these proteins is discussed. Diverse chemical libraries, combinatorial libraries, natural products, as well as unnatural natural products that are derived from combinatorial biology (Chiu [2001] Proc. Natl. Acad. Sci. USA. 98:8548,8553), provide the chemical diversity in the search for new drugs to block new targets. Identifying new compounds that can become drugs is a long, expensive, and arduous task and potential targets must be carefully defined so as not to waste valuable resources. Equally important is the selection of compounds to be future drug candidates. Target selectivity in no way guarantees clinical efficacy, as the compound must meet pharmaceutical requirements, such as solubility, absorption, tissue distribution, and lack of toxicity. Thus matching biological diversity with chemical diversity involves something more than tight interactions, it involves interactions of the compounds with a variety host factors that can modulate its activity. J. Cell. Biochem. Suppl. 37: 1,6, 2001. © 2002 Wiley-Liss, Inc. [source] Theoretical aspects of virus capsid assemblyJOURNAL OF MOLECULAR RECOGNITION, Issue 6 2005Adam Zlotnick Abstract A virus capsid is constructed from many copies of the same protein(s). Molecular recognition is central to capsid assembly. The capsid protein must polymerize in order to create a three-dimensional protein polymer. More than structure is required to understand this self-assembly reaction: one must understand how the pieces come together in solution. Copyright © 2005 John Wiley & Sons, Ltd. [source] Mapping of senescent cell antigen on brain anion exchanger protein (AE) isoforms using HPLC and fast atom bombardment ionization mass spectrometry (FAB-MS)JOURNAL OF MOLECULAR RECOGNITION, Issue 1 2004Marguerite M. Kay Abstract Molecular recognition of senescent cells involves oxidation of a crucial membrane protein leading to generation of a neoantigen, called ,senescent cell antigen' (SCA), and binding of physiologic autoantibodies. These IgG autoantibodies trigger macrophage removal of the cell prior to its lysis at a time when anion transport has decreased but the membrane is still grossly intact. The neoantigen SCA is generated by oxidation of a major anion transport protein called band 3 or anion exchange protein. In this study, we use IgG physiologic autoantibodies from senescent red cells to isolate SCA from brain, and HPLC and fast atom bombardment ionization mass spectrometry (FAB-MS) to compare brain SCA to band 3. HPLC peptide maps of band 3 and SCA showed substantial homology, suggesting that SCA is a subset of band 3, and includes an estimated ,45% of the band 3 molecule. FAB-MS results indicate that residues matching all three band 3 isoforms (AE1, AE2 and AE3) are detected in SCA fractions. These findings suggest that other isoforms of band 3 may undergo the same aging changes that AE1 on red blood cells undergoes to generate SCA. This provides confirmation that SCA is on non-erythroid cell types. Implications of these studies to the generation of neoantigens by oxidation and their recognition by autoantibodies to them are discussed. Copyright © 2003 John Wiley & Sons, Ltd. [source] Crossbar assembly of antibody-functionalized peptide nanotubes via biomimetic molecular recognition,JOURNAL OF PEPTIDE SCIENCE, Issue 2 2008Linglu Yang Abstract Previously, a large scale assembly of nanowires in a parallel array configuration has been demonstrated, and one type of nanowire could interconnect two electrodes in the high-wire density. However, to assemble nanowires into practical logic-gate configurations in integrated circuits, we need more than the parallel assembly of nanowires. For example, when the assembling nanowires are monopolar semiconductors, logic gates such as AND, OR and NOR are to be assembled necessarily from two types of semiconducting nanowires, n -type and p -type, and some of these nanowires must cross perpendicularly to form a crossbar geometry for the logical operation. In this paper, the crossbar assembly of antibody-functionalized peptide nanotubes was demonstrated by a new biomimetic bottom-up technique. Molecular recognition between antigens and antibodies enabled two types of the antibody-functionalized bionanotubes to place them onto targeted locations on substrates, where their complementary antigens were patterned. When two rectangular pads of antigens, human IgG and mouse IgG, were patterned perpendicularly on an Au substrate by nanolithography and then the antihuman IgG nanotubes and the antimouse IgG nanotubes were incubated on this substrate in solution, these bionanotubes were attached onto corresponding locations to form the crossbar configuration. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd. [source] Specific binding of a biotinylated, metallocarbonyl-labelled dendrimer to immobilized avidin detected by diffuse-reflectance infrared Fourier transform spectroscopyAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 3 2004Bogna Rudolf Abstract Molecular recognition between avidin covalently immobilized at the surface of acrylic resin beads and a transition metallocarbonyl tracer of the biotin ligand was detected using diffuse reflectance infrared Fourier transform spectroscopy. Copyright © 2004 John Wiley & Sons, Ltd. [source] Molecular recognition between Escherichia coli enolase and ribonuclease EACTA CRYSTALLOGRAPHICA SECTION D, Issue 9 2010Salima Nurmohamed In Escherichia coli and many other bacterial species, the glycolytic enzyme enolase is a component of the multi-enzyme RNA degradosome, an assembly that is involved in RNA processing and degradation. Enolase is recruited into the degradosome through interactions with a small recognition motif located within the degradosome-scaffolding domain of RNase E. Here, the crystal structure of enolase bound to its cognate site from RNase E (residues 823,850) at 1.9,Å resolution is presented. The structure suggests that enolase may help to organize an adjacent conserved RNA-binding motif in RNase E. [source] Molecular recognition of aminoglycoside antibiotics by ribosomal RNA and resistance enzymes: An analysis of x-ray crystal structuresBIOPOLYMERS, Issue 1 2003Quentin Vicens Abstract The potential of RNA molecules to be used as therapeutic targets by small inhibitors is now well established. In this fascinating wide-open field, aminoglycoside antibiotics constitute the most studied family of RNA binding drugs. Within the last three years, several x-ray crystal structures were solved for aminoglycosides complexed to one of their main natural targets in the bacterial cell, the decoding aminoacyl,tRNA site (A site). Other crystallographic structures have revealed the binding modes of aminoglycosides to the three existing types of resistance-associated enzymes. The present review summarizes the various aspects of the molecular recognition of aminoglycosides by these natural RNA or protein receptors. The analysis and the comparisons of the detailed interactions offer insights that are helpful in designing new generations of antibiotics. © 2003 Wiley Periodicals, Inc. Biopolymers, 2003 [source] Allosteric Tuning of the Intra-Cavity Binding Properties of a Calix[6]arene through External Binding to a ZnII Center Coordinated to Amino Side ChainsCHEMISTRY - A EUROPEAN JOURNAL, Issue 7 2007Ulrich Darbost Dr. Abstract Molecular recognition by calix[6]arene-based receptors bearing three primary alkylamino side chain arms (1) is described. Complexation of ZnII ion provides the dinuclear ,-hydroxo complex , XRD characterization of which, together with solution studies, provided evidence of its hosting of neutral polar organic guests G. Treatment of this complex with a carboxylic acid or a sulfonamide (XH) results in the formation of mononuclear species , one of which (X = Cl) has been characterized by XRD. A dicationic complex is obtained upon treatment of with a mixture of an alkylamine and a strong acid. Each of these ZnII complexes features a tetrahedral metal ion bound to the three amino arms of ligand 1 and to an exogenous ligand (either HO,, X,, or RNH2) sitting outside of the cavity. As a result, the metal ion structures the calixarene core, constraining it in a cone conformation suitable for guest hosting. The receptor properties of these compounds have been explored in detail and are compared with those of the trisammonium receptor , based on the same calixarene core, as well as those of the trisimidazole-based dicationic Zn funnel complexes. This study reveals very different host properties, in spite of the common hydrophobic, ,-basic, and hydrogen-bonding acceptor properties of the calixarene cores. A harder external ligand produces a less polarized receptor that is consequently particularly sensitive to the hydrogen-bonding ability of its guest. The less electron-rich the apical ligand, and a fortiori the trisammonium host, the more sensitive the receptor to the dipole moment of the guest. All this stands in contrast with the funnel Zn complexes, in which the coordination link plays a dominant role. It is also shown that the asymmetry of an exo -coordinated enantiopure amino ligand is sensed by the guest. This supramolecular system nicely illustrates how the receptor properties of a hydrophobic cavity can be allosterically tuned by the environment. [source] Helix Formation in Synthetic Polymers by Hydrogen Bonding with Native Saccharides in Protic MediaCHEMISTRY - A EUROPEAN JOURNAL, Issue 30 2006Minoru Waki Abstract Water-soluble poly(m -ethynylpyridine)s were designed to realize saccharide recognition in protic media. UV/Vis, 1H NMR, and fluorescence measurements revealed that the polymer forms a helical higher order structure by solvophobic interactions between the ethynylpyridine units in the protic medium. The resulting pore in the helix behaves like a binding pocket in proteins, by taking advantage of inwardly directed hydrogen-bonding functional groups of the polymers. Molecular recognition of native saccharides by the polymers was investigated by circular dichroism (CD). The chirality of the saccharide was transferred to the helical sense of the polymers, accompanied by the appearance of induced CDs (ICDs) in the absorptive region of the polymers. In MeOH/water (10/1), mannose and allose showed intense ICDs, and the apparent association constant between the polymer and D -mannose was 14,M,1. [source] Chiral Recognition by Resorcin[4]arene Receptors: Intrinsic Kinetics and DynamicsCHEMISTRY - A EUROPEAN JOURNAL, Issue 17 2004Andrea Tafi Prof. Abstract Molecular recognition of representative amino acids (A) by a chiral amido[4]resorcinarene receptor (1L) was investigated in the gas phase by ESI-FT-ICR mass spectrometry. The ligand displacement reaction between noncovalent diastereomeric [1L,H,A]+ complexes and the 2-aminobutane enantiomers (B) exhibits a distinct enantioselectivity with regard to both the leaving amino acid A and the amine reactant B. The emerging selectivity picture, discussed in the light of molecular mechanics and molecular dynamics calculations, points to chiral recognition by 1L, as determined by the effects of the host asymmetric frame on the structure, stability, and rearrangement dynamics of the diastereomeric [1L,H,A]+ complexes and the orientation of the amine reactant B in encounters with [1L,H,A]+. The results contribute to the development of a dynamic model of chiral recognition of biomolecules by enzyme mimics in the unsolvated state. La spettrometria di massa ESI-FT-ICR è stata impiegata per lo studio del riconoscimento chirale di alcuni amminoacidi rappresentativi (A) da parte di un ammido[4]resorcinarene chirale (1L). La reazione di rilascio dell,amminoacido A dai complessi diastereomerici non covalenti [1L,H,A]+ a seguito dell,attacco degli enantiomeri del 2-amminobutano (B) mostra una distinta enantioselettività sia per quanto riguarda la molecula uscente A che per quanto riguarda il reagente B. Il quadro di reattività ottenuto, discusso alla luce di calcoli di meccanica e dinamica molecolare, indica che il riconoscimento chirale da parte di 1L è determinato dall,effetto della struttura asimmetrica dell, ammido[4]resorcinarene sulla struttura, la stabilità, e la dinamica di riarrangiamento dei suoi complessi diastereomerici [1L,H,A]+ e dall, orientamento dell,ammina reagente B nel complesso di collisione con [1L,H,A]+. I risultati ottenuti contribuiscono allo sviluppo di un modello dinamico per il riconoscimento chirale di biomolecole da parte di enzimi artificiali allo stato non solvatato. [source] Molecular recognition in solid-state crystallization: Colored chiral adduct formations of 1,1,-Bi-2-naphthol derivatives and benzoquinone with a third componentCHIRALITY, Issue 7 2002Yoshitane Imai Abstract Molecular recognition in solid-state crystallization involving derivatives of 1,1,-bi-2-naphthol and benzoquinone was studied. No adduct crystal was formed when crystals of biphenyl were further added as a third component to a grinding mixture of crystals of chiral 1,1,-bi-2-naphthol and benzoquinone, which by itself did not form an adduct. This contrasts with the case in which further addition of naphthalene crystals to the same mixture produced a new red crystal. Adduct formations using chiral 6,6,-dibromo-1,1,-bi-2-naphthol in place of 1,1,-bi-2-naphthol were also studied. In this case, adducts were produced either with or without biphenyl as a third compound, but the colors of the adducts differed significantly in the two cases: red and bluish-black. The same three-component adduct crystals were produced from solid-grinding and solution crystallization and the structure was determined by X-ray diffractometry. Based on the crystal structures, theoretical calculations were carried out to compare the mechanism of colorations in the binary and the ternary complexes. Chirality 14:604,609, 2002. © 2002 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||||||||||||||||||||