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61.
62.
Conditional glycosylation in eukaryotic cells using a biocompatible chemical inducer of dimerization
Czlapinski JL Schelle MW Miller LW Laughlin ST Kohler JJ Cornish VW Bertozzi CR 《Journal of the American Chemical Society》2008,130(40):13186-13187
Chemical inducers of dimerization (CIDs) are cell-permeable small molecules capable of dimerizing two protein targets. The most widely used CID, the natural product rapamycin and its relatives, is immunosuppressive due to interactions with endogenous targets and thus has limited utility in vivo. Here we report a new biocompatible CID, Tmp-SLF, which dimerizes E. coli DHFR and FKBP and has no endogenous mammalian targets that would lead to unwanted in vivo side effects. We employed Tmp-SLF to modulate gene expression in a yeast three-hybrid assay. Finally, we engineered the Golgi-resident glycosyltransferase FucT7 for tunable control by Tmp-SLF in mammalian cells. 相似文献
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Gao H Leary J Carroll KS Bertozzi CR Chen H 《Journal of the American Society for Mass Spectrometry》2007,18(2):167-178
ESI-FTICR MS was utilized to characterize a 4Fe-4S containing protein Mycobacterium tuberculosis APS reductase. This enzyme catalyzes the reduction of APS to sulfite and AMP with reducing equivalents from the protein cofactor, thioredoxin. Under nondenaturing conditions, a distribution of the apoprotein, a 2Fe-2S intermediate, and the 4Fe-4S holoprotein were observed. Accurate mass measurements indicated an oxidation state of +2 for the 4Fe-4S cluster, with no disulfide bond in the holoenzyme. Gas-phase stability of the 4Fe-4S cluster was investigated using both in-source and collision induced dissociation, which provided information regarding the relative gas-phase binding strength of iron towards protein ligands and inorganic sulfides. Noncovalent complexes of the holoprotein with several ligands, including APS, thioredoxin, and AMP, were also investigated. Calculated values of dissociation constants for the complexes indicate that AMP binds with a higher affinity to the enzyme intermediate than to the free enzyme. The implications of the binary and ternary complexes observed by gas-phase noncovalent interactions in the mechanism of APS reduction are discussed. 相似文献
65.
The successful integration of living cells into synthetic devices requires precise control over cell patterning. Here we describe a versatile platform that can accomplish this goal through DNA hybridization. Living cells functionalized with exogenous cell-surface DNA strands bind to cognate sequences of DNA printed on glass slides. Attachment via these "cell-adhesion barcodes" is rapid and specific, with close-packed arrays of cells forming within minutes. The biophysical properties of the system are characterized, and the technique is used to form complex cellular patterns with single-cell line widths and self-assembled cellular microarrays. Key advantages of DNA-directed cell binding include the ability to immobilize both adherent and non-adherent cells, to capture cells selectively from a mixed population, to tune the binding properties of the cells, and to reuse substrates prepared with widely available DNA printing technologies. 相似文献
66.
Elliot C. Woods Nathan A. Yee Jeff Shen Prof. Carolyn R. Bertozzi 《Angewandte Chemie (International ed. in English)》2015,54(52):15782-15788
Synthetic glycopolymers that emulate cell‐surface mucins have been used to elucidate the role of mucin overexpression in cancer. However, because they are internalized within hours, these glycopolymers could not be employed to probe processes that occur on longer time scales. In this work, we tested a panel of glycopolymers bearing a variety of lipids to identify those that persist on cell membranes. Strikingly, we found that cholesterylamine (CholA) anchored glycopolymers are internalized into vesicles that serve as depots for delivery back to the cell surface, allowing for the display of cell‐surface glycopolymers for at least ten days, even while the cells are dividing. As with native mucins, the cell‐surface display of CholA‐anchored glycopolymers influenced the focal adhesion distribution. Furthermore, we show that these mimetics enhance the survival of nonmalignant cells in a zebrafish model of metastasis. CholA‐anchored glycopolymers therefore expand the application of glycocalyx engineering in glycobiology. 相似文献
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BACKGROUND: Sialic acid is a component of many tumor-associated oligosaccharide antigens. The repertoire of sialic acids presented by cells can be expanded to include unnatural variants by intercepting the sialic acid biosynthetic pathway with unnatural precursors. We explored whether unnatural cell surface sialosides produced by metabolism can act as neo-antigens and modulate the immunogenicity of cells. RESULTS: Immunization of rabbits with synthetic conjugates of an unnatural sialic acid bound to keyhole limpet hemocyanin produced significant titers of antibodies that were specific for the structurally altered sialic acid. The antibodies recognized cells that were fed the unnatural biosynthetic precursor, and were capable of directing complement-mediated lysis. CONCLUSIONS: Structural alteration of sialic acids replaces a tolerized self-antigen with an antigenic determinant. Incorporation of unnatural sialosides into cell surface glycoconjugates through biosynthetic means can alter the immunoreactivity of cells, providing new possibilities for tumor immunotherapy. 相似文献
69.
Self-propelled particles with soft-core interactions: patterns, stability, and collapse 总被引:1,自引:0,他引:1
Understanding collective properties of driven particle systems is significant for naturally occurring aggregates and because the knowledge gained can be used as building blocks for the design of artificial ones. We model self-propelling biological or artificial individuals interacting through pairwise attractive and repulsive forces. For the first time, we are able to predict stability and morphology of organization starting from the shape of the two-body interaction. We present a coherent theory, based on fundamental statistical mechanics, for all possible phases of collective motion. 相似文献
70.
Slifer K Amarian M Auerbach L Averett T Berthot J Bertin P Bertozzi B Black T Brash E Brown D Burtin E Calarco J Cates G Chai Z Chen JP Choi S Chudakov E Ciofi Degli Atti C Cisbani E de Jager CW Deur A DiSalvo R Dieterich S Djawotho P Finn M Fissum K Fonvieille H Frullani S Gao H Gao J Garibaldi F Gasparian A Gilad S Gilman R Glamazdin A Glashausser C Glöckle W Golak J Goldberg E Gomez J Gorbenko V Hansen JO Hersman B Holmes R Huber GM Hughes E Humensky B Incerti S Iodice M Jensen S Jiang X 《Physical review letters》2008,101(2):022303
We present a measurement of the spin-dependent cross sections for the 3He over -->(e over -->,e')X reaction in the quasielastic and resonance regions at a four-momentum transfer 0.1< or =Q2< or =0.9 GeV2. The spin-structure functions have been extracted and used to evaluate the nuclear Burkhardt-Cottingham and extended Gerasimov-Drell-Hearn sum rules for the first time. The data are also compared to an impulse approximation calculation and an exact three-body Faddeev calculation in the quasielastic region. 相似文献