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9667889 | Enzyme models: design and selection. | There are two approaches to the discovery of enzyme mimics, that is identifying molecules that are able to bind substrate(s) and then catalyse reactions. The first approach, often inspired by enzymes themselves, utilises chemical knowledge and experience to design the catalyst. The other approach is to create a library... |
9667886 | Molecular recognition of anions by synthetic receptors. | Over the past year, several significant developments have been made in the field of anion binding. The fundamental principles of molecular recognition are increasingly being better understood, and of particular interest are reports of several synthetic anion receptors able to perform their task in complex natural media... |
9667896 | Recognition of neutral species with synthetic receptors. | The design of synthetic receptors for neutral molecules is an area of intense current interest. The area has grown from early work on cyclodextrin or single crown ether complexation to encompass a wide array of receptor shapes and structures. Furthermore, the range of substrate selectivities has increased from simple a... |
9667895 | Computational approaches to molecular recognition. | Recent advances in the computation of free energies have facilitated the understanding of host-guest and protein-ligand recognition. Rigorous perturbation methods have been assessed and expanded, and more approximate techniques have been developed that allow faster treatment of diverse systems. |
9704297 | Graphical visualization of mean hydration from molecular dynamics simulations. | How does one characterize water solvating a complex solute? Specific hydration of proteins and nucleic acids plays a key role in many biological processes. However, traditional pairwise descriptions of solvent structure (radial distribution functions, etc.) are incapable of adequately describing the hydration of these ... |
9648273 | Transfer reactions catalyzed by cyclodextrin glucosyltransferase using 4-thiomaltosyl and C-maltosyl fluorides as artificial donors. | Cyclodextrin glycosyltransferase enzyme from Bacillus circulans catalyzed the effective conversion of 4-thio-alpha-maltosyl fluoride into cyclo-alpha-(1-->4(2))-thiomalto -tetraoside, -pentaoside, -hexaoside and linear hemithiomaltooligosaccharides. However, under the same conditions, C-maltosyl fluoride afforded only ... |
9648262 | Chemoenzymatic synthesis of dendritic sialyl Lewis(x). | Traditional structure activity relationship studies (SAR) have led to the development of numerous sialyl Lewis(x) analogs in the search for potential antiinflammatory agents. However, these methods do not take into account cluster or multivalent effects. Reported herein is the chemoenzymatic synthesis of di-, tetra-, a... |
9648258 | Enzymatic synthesis, isolation, and analysis of novel alpha- and beta-galactosyl-cycloisomalto-octaoses. | Novel branched cycloisomalto-octaoses (CI8s) were enzymatically synthesized by transgalactosylation with alpha-galactosidase from coffee bean and beta-galactosidase preparations from Penicillium multicolor and Bacillus circulans, using melibiose and lactose as donor substrates, and CI8 which is a cyclic homogeneous oli... |
9613811 | Randomness and biospecificity: random copolymers are capable of biospecific molecular recognition in living systems. | Biospecific molecular recognition in living systems is known to be based on the lock and key principle as proposed by Emil Fischer. Based on this concept, biospecific polymers have been produced synthetically by attaching biospecific 'keys' to the polymer chain. We postulate that biospecificity can be achieved by alter... |
9586414 | [Description of a case of Reye's-like syndrome with fatal outcome]. | A Reye Like Syndrome case occurred in a twelve year-old little girl with a previous familiar history is reported. The little patient was admitted in the pediatric ward for fever, vomiting and aspecific respiratory symptoms and developed very quickly a severe metabolic acidosis, alterations of consciousness, hypoxia, ti... |
22358889 | Potential molecular chaperones involved in laminin chain assembly. | To explore potential molecular chaperones involved in the intracellular assembly of laminin chains, bovine aortic endothelial cells were treated with a thiol cleavable divalent cross-linking reagent, dithio-bis-(succinimidylpropionate), and cellular proteins cross-linked to laminin chains were co-immunoprecipitated wit... |
21639178 | Complete enantiomeric separation of phenylthiocarbamoylated amino acids on a tandem column of reversed and chiral stationary phases. | The enantiomeric separation of phenylthiocarbamoyl derivatives of amino acids (PTC-AAs) was studied on a series of reversed phase HPLC columns coupled to the chiral phase HPLC columns. First, the five chiral phases (native, 0.2, 3.3, 7.5 and 16.9 phenylcarbamoylated/β-cyclodextrins, Ph/CD) were newly prepared by modifi... |
21639176 | Determination of accurate electroosmotic mobility and analyte effective mobility values in the presence of charged interacting agents in capillary electrophoresis. | A method for determining the accurate effective mobility value of an analyte in the presence of a charged interacting agent, such as a charged cyclodextrin, a micellar agent, a protein, or a DNA fragment that binds the traditional electroosmotic flow markers, is presented. Part of the capillary is filled with the charg... |
21639174 | A Family of Single-Isomer Chiral Resolving Agents for Capillary Electrophoresis. 2. Hepta-6-sulfato-β-cyclodextrin. | A new, hydrophilic, single-isomer charged cyclodextrin, the sodium salt of hepta-6-sulfato-β-cyclodextrin has been synthesized, characterized, and used for the capillary electrophoretic separation of the enantiomers of numerous noncharged, acidic, basic, and zwitterionic analytes. Hepta-6-sulfato-β-cyclodextrin proved ... |
10477821 | Study of the complexation behaviour of gliclazide with partially methylated beta-cyclodextrin in solution and solid state. | The complexation of Gliclazide (GL) with a partially methylated beta-cyclodextrin was studied. Phase-solubility and (1)H NMR spectroscopy were employed to investigate the complexation behaviour in solution and to demonstrate the complexation in liquid medium with the participation of both azabicyclooctyl and tolyl moie... |
11671996 | Novel Method to Prepare Dihydroxy Permethylated beta-Cyclodextrin Isomeric Intermediates for Bifunctional Enzyme Mimics. | Natural beta-cyclodextrin was treated with 3.5 equiv of tert-butyldimethylsilyl chloride and then with NaH and MeI in the same reaction vessel to give a mixture of oligosilyl-substituted permethylated beta-cyclodextrins. The mixture was treated with NH(4)F and the resulting 6(A),6(D)-(1), 6(A),6(C)-(2), and 6(A),6(B)-(... |
11671987 | A New Generation of "Cholaphanes": Steroid-Derived Macrocyclic Hosts with Enhanced Solubility and Controlled Flexibility. | The macrocyclic "cholaphanes" 3a-c were synthesized from the inexpensive steroid cholic acid. Like earlier relatives they feature substantial cavities with inward-directed hydroxyl groups, suitable for binding polar molecules such as carbohydrates in nonpolar media. New features are the externally directed alkyl chains... |
11671986 | Novel Ring Contraction Reaction for the Synthesis of Functionalized Tetrathiamacrocyclic Ligand Molecules. | Chlorination of [14]aneS(4)-ol (1,4,8,11-tetrathiatetradecan-6-ol) and cis/trans-[14]aneS(4)-diol (cis/trans-1,4,8,11-tetrathiatetradecane-6,13-diol) yields the corresponding dichloro-substituted macrocycles [14]aneS(4)-Cl (1,4,8,11-tetrathiatetradecane 6-chloride) and cis/trans-[14]aneS(4)-Cl(2) (cis/trans-1,4,8,11-te... |
11671972 | Conformation, Inversion Barrier, and Solvent-Induced Conformational Shift in Exo- and Endo/Exo-Calix[4]arenes. | Calixarenes 4a and 4b having hydroxyl groups in endo and exo positions and the ethanediyl-bridged exo-calixarene 5a were synthesized by a stepwise strategy. Single-crystal X-ray structures were obtained for 4a and for the exo-calixarene 3d, showing the molecules to exist in the 1,2-alternate conformation which is also ... |
11671935 | Preparations of Trisubstituted Hydrazines and Pyrazolidines from N-(1-Benzotriazolylalkyl)hydrazines. | Reactions of N,N'-disubstituted hydrazines with benzotriazole and aldehydes give N-(alpha-benzotriazoylalkyl)-N,N'-disubstituted hydrazines which on treatment with organometallic reagents form N-alkyl-N,N'-disubstituted hydrazines in good yields. N-(Benzotriazolylalkyl)-N,N'-disubstituted hydrazines and electron-rich o... |
11671909 | Synthesis, Optical Resolution and Complexation Properties of Inherently Chiral Monoalkylated p-tert-Butyl-(1,2)-calix[4]crown Ethers. | Reaction of mono-O-alkylated calix[4]arenes 2 with tri- to pentaethylene glycol ditosylates and K(2)CO(3) affords asymmetrical (1,2)-calix[4]crown ether derivatives 3 as the main product, along with minor amounts of calix[4]arene dimers 4 and mixed syn-distal di-O-alkylated calix[4]arenes 5. A reaction mechanism for th... |
15739322 | [The use of enthalpy-entropy compensation in the study of retention mechanism of aromatic positional isomers]. | In this paper, the thermodynamic parameters of the separation process of six groups of aromatic positional isomers on nine crown ether polysiloxane, OV-1701 and Carbowax-20M capillary chromatographic columns have been investigated systematically. The Gibbs free energies for every compound at harmonic mean temperature, ... |
9514117 | Synthesis and characterization of supramolecular protein aggregates: self-assembled, molecularly-ordered, tubes from electrostatic complementation of glutamine synthetase dodecamers. | Dodecameric Escherichia coli glutamine synthetase (GS) is formed from identical subunits arranged in face-to-face hexameric rings. In the presence of Zn2+ and other transition metal ions the individual dodecamers 'stack' to form protein tubes. Previous results have suggested that six binuclear intermolecular metal bind... |
9511989 | Oligosaccharide-derivatized dendrimers: defined multivalent inhibitors of the adherence of the cholera toxin B subunit and the heat labile enterotoxin of E. coli to GM1. | Poly(propylene imine) dendrimers having four or eight primary amino groups and a Starburst (PAMAM) dendrimer having eight primary amino groups were used as core molecules, to which phenylisothiocyanate derivatized (PITC) galbeta1-3galNAcbeta1-4[sialic acid alpha2-3]-galbeta1-4glc (oligo-GM1) residues were covalently at... |
9456045 | Capillary electrophoretic separations of enantiomers using cyclodextrin-containing background electrolytes. | The 1996 primary literature papers which deal with the separation of enantiomers using cyclodextrins are reviewed here. Though the majority of the papers still use the neutral native cyclodextrins or the neutral derivatized cyclodextrins as resolving agents, there was a significant increase in number of separations whi... |
9456034 | Methods for the estimation of binding constants by capillary electrophoresis. | Capillary electrophoresis (CE) has developed into a particularly effective means to determine apparent equilibrium constants for molecular association in solution (e.g., to micelles, cyclodextrins, antibiotics, proteins, RNA, DNA, etc.). The various experimental, graphical and mathematical approaches for determining as... |
9449579 | Preparation of (R)-N-methylsalsolinol via reversed-phase high-performance liquid chromatography using beta-cyclodextrin as a mobile-phase additive. | A new preparation method was devised using beta-cyclodextrin as a mobile-phase additive in a reversed-phase high-performance liquid chromatography system. Preparative separation of the biologically active (R)-enantiomer was achieved from racemic N-methylsalsolinol. Beta-cyclodextrin was removed completely in good yield... |
9490114 | [On the supramolecular structure of eye lens crystalline. A study by small-angle x-ray scattering]. | The supramolecular structure of clystallins from bovine and frog eye lens tissues was studied by small-angle X-ray scattering. The measurements were carried out at different orientations of the lens tissue on a diffractometer equipped with a coordinate detector with point collimation of the X-ray beam. The results indi... |
9435856 | Tumor-specific T-bodies: towards clinical application. | Unlike antibodies, T cells are well suited to penetrate and destroy solid tumors. The T-body approach combines antibody recognition and T cells effector function. It is based on T cells expressing chimeric receptors composed of antibody-derived Fv or scFv as their extracellular recognition elements joined to lymphocyte... |
9434920 | Effects of early treatment with immunoglobulin on critical illness polyneuropathy following multiple organ failure and gram-negative sepsis. | <h4>Objective</h4>The evaluation of incidences and relating factors of severe persisting critical illness polyneuropathy (CIP) in survivors of multiple organ failure (MOF).<h4>Design</h4>Prospective study with an entry period of 24 months. Electrophysiological studies for the diagnosis of CIP were performed 1 or 2 days... |
9518195 | [Immunology in the severely injured]. | Immunological complications frequently occur during the clinical course in patients with multiple injuries. The increased release of pro-inflammatory mediators during the immunological response to trauma may lead to the systemic inflammatory response syndrome (SIRS) and furthermore, to multisystem organ failure (MOF), ... |
9431988 | The C-terminal domain V of perlecan promotes beta1 integrin-mediated cell adhesion, binds heparin, nidogen and fibulin-2 and can be modified by glycosaminoglycans. | Domain V of the major basement-membrane proteoglycan perlecan, a domain which consists of three laminin type G (LG) and four epidermal-growth-factor-like (EG) modules, was obtained in recombinant form by transfecting embryonic kidney cells with an episomal expression vector. A major 90-kDa fragment V was obtained toget... |
9421730 | Selection for high levamisole resistance in Haemonchus contortus monitored with an egg-hatch assay. | To investigate the characteristics of selection for levamisole resistance in Haemonchus contortus, the consecutive nematode generations of an in vivo selection were monitored with a newly developed egg-hatch assay. The in vivo selection was started with a population not previously exposed to any anthelmintics (SHS). At... |
9421268 | The X1X2Y sex chromosome system in the fish Hoplias malabaricus. I. G-, C- and chromosome replication banding. | Hoplias malabaricus, a widely distributed neotropical fish (Central America to Argentina), may represent a group of distinct species showing diversified cytotypes with respect to chromosome number, morphology and sex systems. One of these karyotypic forms is characterized by an X1X1X2X2/X1X2Y sex chromosome system, wit... |
9421267 | Non-telomeric chromosome localization of (TTAGGG)n repeats in the genus Eulemur. | The chromosomal distribution of the (TTAGGG)n telomeric repetitive sequences was studied in the Malagasy species Eulemur fulvus fulvus (2n = 60), Eulemur rubriventer (2n = 50), Eulemur coronatus (2n = 46) and Eulemur macaco (2n = 44). These sequences hybridize to the telomeres of all chromosomes of the four species and... |
9421266 | Recent evolution of NOR-bearing and sex chromosomes of the North African rodent Lemniscomys barbarus. | The karyotype and meiotic phases of Lemniscomys barbarus from Morocco were extensively studied with G- and C-banding, Ag-NOR and fluorochrome staining, in situ hybridization with an rDNA probe, and synaptonemal complex analysis. Comparison of the data with those previously published for an Algerian specimen revealed in... |
9421265 | Nature of B chromosomes in the harvest mouse Reithrodontomys megalotis by fluorescence in situ hybridization (FISH). | Using fluorescence in situ hybridization, we examined the characteristics of two types of B chromosomes in harvest mice of the genus Reithrodontomys. B chromosomes were interrogated with rDNA, telomeric repeat, LINE element and centromeric heterochromatin probes. The two types of B chromosomes share the following featu... |
9421264 | The prevalence of a YY synaptonemal complex over XY synapsis in an XYY man with exclusive XYY spermatocytes. | An infertile XYY man was studied by synaptonemal complex analysis of microspread spermatocytes and by quantitation of germ cells in semithin sections. All the 74 spermatocytes micrographed have an XYY constitution, and the biopsy shows a homogeneous arrest of spermatogenesis at the spermatocyte/young spermatid stages. ... |
9421263 | Using PRINS for gene mapping in polytene chromosomes. | We have adapted the primed in situ labelling (PRINS) protocol for gene mapping in polytene chromosomes of two dipteran species. The method was used to localize the genes for the Balbiani ring (BR) 2.1 and the iron-regulatory protein 1A (IRP1A) in polytene salivary gland chromosomes of Chironomus tentans, and Drosophila... |
9421262 | Sequential G-banding FISH on human sperm chromosomes. | A method that allows the performance of double-colour chromosome painting (FISH) on previously G-banded human sperm metaphases has been developed. Sperm chromosomes were obtained by using the fusion technique between zona-free hamster oocytes and human spermatozoa. Single- and double-colour chromosome painting was perf... |
9421261 | Karyotype analysis of Helianthus annuus using Giemsa banding and fluorescence in situ hybridization. | The karyotype of H. annuus was analysed by computer-aided image processing with respect to the chromosome length, arm ratio, occurrence and chromosomal position of intercalary heterochromatin and the location of 18S/25S and 5S ribosomal RNA genes. The karyotype was subdivided into a group of four acrocentric chromosome... |
9421260 | Development-dependent inheritance of 5-azacytidine-induced epimutations in triticale: analysis of rDNA expression patterns. | Genomic imprinting of rye origin rDNA sequences in triticale is modulated by DNA methylation responsible for ontogenic expression patterns of those sequences. Considering the dynamic nature of these phenomena, we evaluated the influence of plant development on the inheritance of modified rye rDNA expression patterns. D... |
9421186 | Effects of sphingomyelin and phosphatidylcholine degradation on cyclodextrin-mediated cholesterol efflux in cultured fibroblasts. | The hydrolysis of plasma membrane sphingomyelin is known to dramatically alter cellular cholesterol homeostasis in different ways, whereas the degradation of plasma membrane phosphatidylcholine has much less or no effects on cell cholesterol homeostasis [Pörn, Ares, Slotte, J. Lipid Res. 34 (1993) 1385-1392]. In this s... |
9416422 | The influence of molecular conformation upon the self-assembly of cyclohexane diamide diacids. | <h4>Background</h4>Information regarding the self-association of small peptide motifs can be used in the design of peptide microstructures. Previous work in our laboratories illustrated the self-association of certain diamide diacids into microcapsules. In this report a series of cyclohexane diamide diacids are investi... |
9409761 | Lateral self-assembly of E-cadherin directed by cooperative calcium binding. | We report the Ca2+ binding characteristics of recombinant Ecad12, a construct spanning the first two repeats of epithelial cadherin, and demonstrate the links between Ca2+ binding and dimer formation. Sedimentation equilibrium and dynamic light scattering experiments show that weak dimerization of Ecad12 occurs in the ... |
9407553 | Histone H2A significantly enhances in vitro DNA transfection. | <h4>Background</h4>Gene transfer is a potential treatment modality of genetic disease. Efficient, practical methods of DNA transfection are currently under investigation.<h4>Materials and methods</h4>A beta-galactosidase reporter plasmid interacted electrostatically with histones, poly-L-Lys, poly-L-Arg, and a combinat... |
9407548 | Tumor antigens discovery: perspectives for cancer therapy. | The adoptive transfer of cytotoxic T lymphocytes (CTLs) derived from tumor-infiltrating lymphocytes (TIL) along with interleukin 2 (IL-2) into autologous patients with cancer resulted in the objective regression of tumor, indicating that these CTLs recognized cancer rejection antigens on tumor cells. To understand the ... |
9404072 | Structural property and in vitro self-assembly of shark type I collagen. | The main structure of shark type I collagen is similar to that of land mammals, with a partial difference in amino acid sequence and post-translational modification. By static light scattering, the weight-average molecular weight of shark collagen (7.52 x 10(5)) suggests the presence of some aggregated molecules, oligo... |
9402556 | A simple method, using 2-hydroxypropyl-beta-cyclodextrin, of administering alpha-chloralose at room temperature. | Effective long term stable anaesthesia is a goal of many drug regimens employed in neuroscience in which procedures carried out are not practical in awake animals. A particular problem is the study of nociceptive mechanisms where good anaesthesia is essential. Similarly studies of cardiovascular or cerebrovascular mech... |
9401924 | Structure and supramolecular packing features of the dipeptide Arg-Val acetate. | The title compound crystallizes in the zwitterionic form. The crystal forms a supramolecular structure with the peptide molecules organized in head-to-tail columns in the b direction. The arginine side-chains and acetate ions interact with neighbor peptides in the c direction. Infinite hydrophobic columns are present i... |
9351838 | Intramolecular synapsis of duplex DNA by vaccinia topoisomerase. | Complexes formed by vaccinia topoisomerase I on plasmid DNA were visualized by electron microscopy. The enzyme formed intramolecular loop structures in which non-contiguous DNA segments were synapsed within filamentous protein stems. At high enzyme concentrations the DNA appeared to be zipped up within the protein fila... |
9400365 | Model of a quinary structure between Krebs TCA cycle enzymes: a model for the metabolon. | The enzymes which are responsible for catalyzing sequential reactions in several metabolic pathways have been proposed to be highly organized in supramolecular complexes termed metabolons. However, the in situ existence of these weak complexes is difficult to demonstrate because many of them are dissociated during isol... |
9371763 | Functional analysis of DNA bending and unwinding by the high mobility group domain of LEF-1. | LEF-1 (lymphoid enhancer-binding factor 1) is a cell type-specific member of the family of high mobility group (HMG) domain proteins that recognizes a specific nucleotide sequence in the T cell receptor (TCR) alpha enhancer. In this study, we extend the analysis of the DNA-binding properties of LEF-1 and examine their ... |
9371761 | Isolation and bacterial expression of a sesquiterpene synthase cDNA clone from peppermint (Mentha x piperita, L.) that produces the aphid alarm pheromone (E)-beta-farnesene. | (E)-beta-Farnesene is a sesquiterpene semiochemical that is used extensively by both plants and insects for communication. This acyclic olefin is found in the essential oil of peppermint (Mentha x piperita) and can be synthesized from farnesyl diphosphate by a cell-free extract of peppermint secretory gland cells. A cD... |
9395337 | Supramolecular assemblies from lysosomal matrix proteins and complex lipids. | Most lysosomal hydrolases are soluble enzymes. Lamp-II (lysosome-associated membrane protein-II) is a major constituent of the lysosomal membrane. We studied the aggregation of a series of lysosomal molecules. The aggregation-sensitive lysosomal marker enzymes were optimally aggregated at intralysosomal pH. A similar p... |
9395319 | Helix stability in barstar peptides. | The complex between the ribonuclease barnase and barstar, its intracellular inhibitor, is a very good model for studying protein folding and molecular recognition. We have studied the stability of different peptides that cover the barstar alpha-helix2 involved in the binding to barnase. A linear correlation between the... |
9395093 | An electrospray ionisation mass spectrometry (ESI-MS) study to probe the metal ion binding site in the DNA binding domain of the yeast transcriptional activator GAL4. | Electrospray ionisation mass spectrometry (ESI-MS) is used to detect metal ions and their stoichiometry of binding in the DNA binding domain of GAL4. In this analysis, the mass spectra of the apo- and metallo-proteins differ by both mass and charge, precluding the possibility of random adduct formation. Deuterium excha... |
9392424 | Use of cyclodextrins for manipulating cellular cholesterol content. | Previous studies from this laboratory have demonstrated that exposure of tissue culture cells to cyclodextrins results in rapid cholesterol depletion. In the present study, we have developed experimental systems for using solutions of cyclodextrins, either 2-hydroxypropyl beta-cyclodextrin or methylated beta-cyclodextr... |
9385643 | Anatomy of a conformational transition of beta-strand 6 in soybean beta-amylase caused by substrate (or inhibitor) binding to the catalytical site. | A computational study of the five soybean beta-amylase X-ray structure reported so far revealed a peculiar conformational transition after substrate (or inhibitor) binding, which affects a segment of the beta-strand 6 (residues 341-343) in the (beta/alpha)8 molecular scaffold. Backbone distortions that involve consider... |
9385636 | Green fluorescent protein as a signal for protein-protein interactions. | Green fluorescent protein (GFP) is autofluorescent. This property has made GFP useful in monitoring in vivo activities such as gene expression and protein localization. We find that GFP can be used in vitro to reveal and characterize protein-protein interactions. The interaction between the S-peptide and S-protein frag... |
9385633 | TESS: a geometric hashing algorithm for deriving 3D coordinate templates for searching structural databases. Application to enzyme active sites. | It is well established that sequence templates such as those in the PROSITE and PRINTS databases are powerful tools for predicting the biological function and tertiary structure for newly derived protein sequences. The number of X-ray and NMR protein structures is increasing rapidly and it is apparent that a 3D equival... |
9385632 | Crystal structure of cyclophilin A complexed with a binding site peptide from the HIV-1 capsid protein. | The cellular protein, cyclophilin A (CypA), is incorporated into the virion of the type 1 human immunodeficiency virus (HIV-1) via a direct interaction with the capsid domain of the viral Gag polyprotein. We demonstrate that the capsid sequence 87His-Ala-Gly-Pro-Ile-Ala92 (87HAGPIA92) encompasses the primary cyclophili... |
9385446 | A study of supramolecular organization of glycogenolytic enzymes in vertebrate muscle tissue. | Under conditions preventing the direct binding of phosphorylase kinase to glycogen, we detected the formation of the compound ternary complex of glycogen, phosphorylase and phosphorylase kinase. The complex formation occurs in two stages: (i) the formation of phosphorylase-glycogen complex controlled by ATP, (ii) the b... |
9384530 | RNA aptamers to the peptidyl transferase inhibitor chloramphenicol. | <h4>Background</h4>The problem of how macromolecules adopt specific shapes to recognize small molecules in their environment is readily addressed through in vitro selections (the SELEX protocol). RNA-antibiotic interactions are particularly attractive systems for study because they provide an opportunity to expand our ... |
9384529 | Structural basis of DNA folding and recognition in an AMP-DNA aptamer complex: distinct architectures but common recognition motifs for DNA and RNA aptamers complexed to AMP. | <h4>Background</h4>Structural studies by nuclear magnetic resonance (NMR) of RNA and DNA aptamer complexes identified through in vitro selection and amplification have provided a wealth of information on RNA and DNA tertiary structure and molecular recognition in solution. The RNA and DNA aptamers that target ATP (and ... |
9383745 | Fractal analysis of beta-cyclodextrin-indomethacin particles compacted by ultrasound. | An association between indomethacin and beta-cyclodextrin (beta-CD) was obtained by compacting a 1:2 molar physical mixture by ultrasound. The product prepared by this technique was compared with the initial physical mixture and with materials having the same composition but prepared by a simple compaction and kneading... |
9383727 | Binding of substituted acetic acids to alpha-cyclodextrin in aqueous solution. | Complex binding constants of 23 aliphatic acids with alpha-cyclodextrin in aqueous solution were measured by potentiometry, solubility, or competitive spectrophotometry at 25 degrees C. All systems formed 1:1 acid:cyclodextrin complexes, and some of them also formed 1:2 complexes. The conjugate acids formed stronger co... |
9382804 | Chromatin containing CENP-A and alpha-satellite DNA is a major component of the inner kinetochore plate. | The pathway of molecular interactions leading to kinetochore assembly on mammalian chromosomes is unknown. Kinetochores could be specified by structural features of centromeric satellite DNA [1-3] or by specific DNA sequences, analogous to budding yeast centromeres, interspersed in centromeric satellite DNA arrays [4,5... |
9384502 | Heterologous expression of rat epitope-tagged histamine H2 receptors in insect Sf9 cells. | 1. Rat histamine H2 receptors were epitope-tagged with six histidine residues at the C-terminus to allow immunological detection of the receptor. Recombinant baculoviruses containing the epitope-tagged H2 receptor were prepared and were used to infect insect Sf9 cells. 2. The His-tagged H2 receptors expressed in insect... |
9374862 | The molecular basis of Celmer's rules: the stereochemistry of the condensation step in chain extension on the erythromycin polyketide synthase. | Modular polyketide synthases (PKSs), for example, the 6-deoxyerythronolide B synthase (DEBS) responsible for synthesis of the aglycone core of the macrolide antibiotic erythromycin, generate an impressive diversity of asymmetric centers in their polyketide products. However, as noted by Celmer, macrolides have the same... |
9371367 | Pharmacokinetics of itraconazole (oral solution) in two groups of human immunodeficiency virus-infected adults with oral candidiasis. | The pharmacokinetics of itraconazole formulated in a hydroxypropyl-beta-cyclodextrin oral solution was determined for two groups of human immunodeficiency virus (HIV)-infected adults with oral candidiasis (group A, 12 patients with CD4+ T-cell count of >200/mm3 and no AIDS, and group B, 11 patients with CD4+ T-cell cou... |
9371343 | Semiquantitation of cooperativity in binding of vancomycin-group antibiotics to vancomycin-susceptible and -resistant organisms. | The association of vancomycin group antibiotics with the growing bacterial cell wall was investigated by using the cell wall precursor analog di-N-acetyl-Lys-D-Ala-D-Ala in competition binding experiments. The affinities of the antibiotics for the -D-Ala-D-Ala-containing cell wall precursors of Bacillus subtilis ATCC 6... |
9370469 | Pressure effects on the proximal heme pocket in myoglobin probed by Raman and near-infrared absorption spectroscopy. | The influence of high pressure on the heme protein conformation of myoglobin in different ligation states is studied using Raman spectroscopy over the temperature range from 30 to 295 K. Photostationary experiments monitoring the oxidation state marker bands demonstrate the change of rebinding rate with pressure. While... |
9370428 | A 5-nanosecond molecular dynamics trajectory for B-DNA: analysis of structure, motions, and solvation. | We report the results of four new molecular dynamics (MD) simulations on the DNA duplex of sequence d(CGCGAATTCGCG)2, including explicit consideration of solvent water, and a sufficient number of Na+ counterions to provide electroneutrality to the system. Our simulations are configured particularly to characterize the ... |
9370422 | Protein attraction in membranes induced by lipid fluctuations. | The nonspecific lipid-mediated attraction between two proteins embedded in a bilayer membrane have been investigated for a model system using Monte Carlo simulations. We found two types of attraction with different regimes. A depletion-induced attraction in the range r < sigmaL, where sigmaL is the diameter of a lipid ... |
9367341 | Targeting of substrates to the 26S proteasome. | The ubiquitin-proteasome pathway is the principal mechanism for the turnover of short-lived proteins in eukaryotic cells. In this pathway, the covalent ligation of ubiquitin to the substrate is a signal for recognition by the 26S proteasome. Recent studies indicate that targeting of substrates of the ubiquitin pathway ... |
9362483 | Several cooperating binding sites mediate the interaction of a lysosomal enzyme with phosphotransferase. | Lysosomal targeting of soluble lysosomal hydrolases is mediated by mannose 6-phosphate receptors, which recognize and bind mannose 6-phosphate residues in the oligosaccharide chains of proteins destined for delivery to lysosomes. This recognition marker is generated by the sequential action of two enzymes, the first of... |
9362482 | Domain structure and intramolecular regulation of dynamin GTPase. | Dynamin is a 100 kDa GTPase required for receptor-mediated endocytosis, functioning as the key regulator of the late stages of clathrin-coated vesicle budding. It is specifically targeted to clathrin-coated pits where it self-assembles into 'collars' required for detachment of coated vesicles from the plasma membrane. ... |
9362477 | Converting blood coagulation factor IXa into factor Xa: dramatic increase in amidolytic activity identifies important active site determinants. | The coagulation factors IXa (fIXa) and Xa (fXa) share extensive structural and functional homology; both cleave natural substrates effectively only with a cofactor at a phospholipid surface. However, the amidolytic activity of fIXa is 10(4)-fold lower than that of fXa. To identify determinants of this poor reactivity, ... |
9360948 | Gly-Pro-Arg confers stability similar to Gly-Pro-Hyp in the collagen triple-helix of host-guest peptides. | A set of host-guest peptides of the form Ac(Gly-Pro-Hyp)3-Gly-X-Y-(Gly-Pro-Hyp)4-Gly-Gly-NH2 has been designed to evaluate the propensity of different Gly-X-Y triplets for the triple-helix conformation (Shah, N. K., Ramshaw, J. A. M., Kirkpatrick, A., Shah, C., and Brodsky, B. (1996) Biochemistry 35, 10262-10268). All ... |
9362073 | Characterization of cell-matrix adhesion requirements for the formation of fascin microspikes. | Cell adhesion to thrombospondin-1 (TSP-1) correlates with assembly of cell-substratum contact structures that contain fascin microspikes. In this analysis, cell-matrix requirements for assembly of fascin microspikes were examined in detail. In six cell lines, cell spreading on a TSP-1 substratum correlated with express... |
9358153 | Functional recognition of fragmented operator sites by R17/MS2 coat protein, a translational repressor. | The R17/MS2 coat protein serves as a translational repressor of replicase by binding to a 19 nt RNA hairpin containing the Shine-Dalgarno sequence and the initiation codon of the replicase gene. We have explored the structural features of the RNA operator site that are necessary for efficient translational repression b... |
9358151 | Oligonucleotide dendrimers: synthesis and use as polylabelled DNA probes. | Oligonucleotide dendrimers were synthesized using a novel phosphoramidite synthon, tris-2,2,2-[3-(4,4'-dimethoxytrityloxy) propyloxymethyl]ethyl- N , N -diisopropylaminocyanethoxy phosphoramidite. Label, incorporated using [gamma-32P]ATP and polynucleotide kinase, was increased in proportion to the number of 5'-ends. T... |
9356504 | Deciphering a neural code for vision. | Deciphering the information that eyes, ears, and other sensory organs transmit to the brain is important for understanding the neural basis of behavior. Recordings from single sensory nerve cells have yielded useful insights, but single neurons generally do not mediate behavior; networks of neurons do. Monitoring the a... |
9356443 | RNA-peptide fusions for the in vitro selection of peptides and proteins. | Covalent fusions between an mRNA and the peptide or protein that it encodes can be generated by in vitro translation of synthetic mRNAs that carry puromycin, a peptidyl acceptor antibiotic, at their 3' end. The stable linkage between the informational (nucleic acid) and functional (peptide) domains of the resulting joi... |
9358853 | Localization of B-DNA and Z-DNA in terminally differentiating fiber cells in the adult lens. | We examined histochemically and immunohistochemically the distribution of B- and Z-DNA in the epithelium and terminally differentiating dog lens fiber cells. On the basis of anti-DNA antibody reactivity, qualitative and quantitative data on B- and Z-DNA in cells were determined. Anti-B-DNA immunoreactivity gradually de... |
9358444 | High relaxivity linear Gd(DTPA)-polymer conjugates: the role of hydrophobic interactions. | A series of linear copolymers of DTPA-class Gd3+ conjugates, linked by alpha, omega-alkyldiamides with a varying number (n) of methylenes separating the amide function, were synthesized. Surprisingly, their relaxivities at all fields increased with increasing n. At MRI fields and 35 degrees C, the relaxivities of the n... |
9351965 | New light on TRP and TRPL. | Store-operated Ca2+ entry, a mode of Ca2+ influx activated by depletion of Ca2+ from the internal stores, has been detected in a wide variety of cell types and may be the primary mechanism for Ca2+ entry in nonexcitable cells. Nevertheless, until recently, no candidate store-operated channel (SOC) had been identified m... |
9353055 | Differences in coughing and other responses to intrabronchial infection with Bordetella pertussis among strains of rats. | Four strains of rats were each infected intrabronchially with approximately 10(8) CFU of Bordetella pertussis 18-323 encased in fine agarose beads. After 8 days, Sprague-Dawley rats developed the highest incidence of coughing paroxysms, as monitored with voice-activated tape recorders; Brown Norway, Lewis, and Hooded L... |
9353025 | Binding of diarrheagenic Escherichia coli to 32- to 33-kilodalton human intestinal brush border proteins. | We have detected human intestinal brush border proteins to which Escherichia coli strains adhere by means of a blotting-nitrocellulose method in which the binding of radiolabeled bacteria to sodium dodecyl sulfate-polyacrylamide gel electrophoresis-separated intestinal cell membranes was evaluated. The brush border fra... |
9352908 | Promoter-specific repression of fimB expression by the Escherichia coli nucleoid-associated protein H-NS. | The H-NS protein is a major component of the Escherichia coli nucleoid. Mutations in hns, the gene encoding H-NS, have pleiotropic effects on the cell altering both the expression of a variety of unlinked genes and the inversion rate of the DNA element containing the fimA promoter. We investigated the interaction betwe... |
9352902 | Thermosensing properties of mutant aspartate chemoreceptors with methyl-accepting sites replaced singly or multiply by alanine. | The aspartate chemoreceptor Tar has a thermosensing function that is modulated by covalent modification of its four methylation sites (Gln295, Glu302, Gln309, and Glu491). Without posttranslational deamidation, Tar has no thermosensing ability. When Gln295 and Gln309 are deamidated to Glu, the unmethylated and heavily ... |
9352898 | Positive regulation of Shigella flexneri virulence genes by integration host factor. | In Shigella flexneri, expression of the plasmid-encoded virulence genes is regulated via a complex cascade involving DNA topology, specific transactivators, and the nucleoid-associated protein H-NS, which represses transcription under inappropriate environmental conditions. We have investigated the involvement of a sec... |
9348278 | Ca2+ homeostasis in the endoplasmic reticulum: coexistence of high and low [Ca2+] subcompartments in intact HeLa cells. | Two recombinant aequorin isoforms with different Ca2+ affinities, specifically targeted to the endoplasmic reticulum (ER), were used in parallel to investigate free Ca2+ homeostasis in the lumen of this organelle. Here we show that, although identically and homogeneously distributed in the ER system, as revealed by bot... |
9581564 | The N-terminal Arg2, Arg3 and Arg4 of human lactoferrin interact with sulphated molecules but not with the receptor present on Jurkat human lymphoblastic T-cells. | We previously characterized a 105 kDa receptor for human lactoferrin (hLf) on Jurkat human lymphoblastic T-cells. To delineate the role of the basic cluster Arg2-Arg3-Arg4-Arg5 of hLf in the interaction with Jurkat cells, we isolated N-terminally deleted hLf species of molecular mass 80 kDa lacking two, three or four N... |
9581538 | Cucurbitacins are insect steroid hormone antagonists acting at the ecdysteroid receptor. | Two triterpenoids, cucurbitacins B and D, have been isolated from seeds of Iberis umbellata (Cruciferae) and shown to be responsible for the antagonistic activity of a methanolic extract of this species in preventing the 20-hydroxyecdysone (20E)-induced morphological changes in the Drosophila melanogaster BII permanent... |
9343437 | Tissue-specific splicing and functions of the Drosophila transcription factor Grainyhead. | Grainyhead belongs to a recently identified group of transcription factors which share a 250-amino-acid domain required for binding to DNA and a carboxy-terminal dimerization domain. The activities of Grainyhead and other members of the family appear to be modulated so that they can participate in different development... |
9343429 | Protein and DNA contact surfaces that mediate the selective action of the Phox1 homeodomain at the c-fos serum response element. | The human homeodomain protein Phox1 can impart serum-responsive transcriptional activity to the c-fos serum response element (SRE) by interacting with serum response factor (SRF). This activity is shared with other Paired class homeodomains but not with more distantly related homeodomains. To understand the mechanism o... |
9343257 | Cross-clade human immunodeficiency virus (HIV)-specific cytotoxic T-lymphocyte responses in HIV-infected Zambians. | We have examined cross-clade HIV-specific cytotoxic T-lymphocyte (CTL) activity in peripheral blood of eight Zambian individuals infected with non-B-clade human immunodeficiency virus type 1 (HIV-1). Heteroduplex mobility assay and partial sequence analysis of env and gag genes strongly suggests that all the HIV-infect... |
9343255 | Details of the arrangement of the outer capsid of rice dwarf phytoreovirus, as visualized by two-dimensional crystallography. | Two-dimensional crystals were obtained from purified P8, an outer capsid protein of rice dwarf phytoreovirus. A filtered image of the two-dimensional crystal, in combination with the results of biochemical analysis, revealed the unit formation of the capsid protein, a capsomere structure, which appeared to be an approx... |
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