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91.
Rabuka D Forstner MB Groves JT Bertozzi CR 《Journal of the American Chemical Society》2008,130(18):5947-5953
The controlled addition of structurally defined components to live cell membranes can facilitate the molecular level analysis of cell surface phenomena. Here we demonstrate that cell surfaces can be engineered to display synthetic bioactive polymers at defined densities by exogenous membrane insertion. The polymers were designed to mimic native cell-surface mucin glycoproteins, which are defined by their dense glycosylation patterns and rod-like structures. End-functionalization with a hydrophobic anchor permitted incorporation into the membranes of live cultured cells. We probed the dynamic behavior of cell-bound glycopolymers bearing various hydrophobic anchors and glycan structures using fluorescence correlation spectroscopy (FCS). Their diffusion properties mirrored those of many natural membrane-associated biomolecules. Furthermore, the membrane-bound glycopolymers were internalized into early endosomes similarly to endogenous membrane components and were capable of specific interactions with protein receptors. This system provides a platform to study cell-surface phenomena with a degree of chemical control that cannot be achieved using conventional biological tools. 相似文献
92.
Hungerford G Rei A Ferreira MI Suhling K Tregidgo C 《The journal of physical chemistry. B》2007,111(13):3558-3562
Time-resolved fluorescence anisotropy and fluorescence recovery after photobleaching were applied to study the diffusion of dyes and a fluorescence-labeled enzyme in a sol-gel-derived medium. This type of medium exhibits attractive properties such as robustness, low processing temperature, high porosity, large internal surface area, and can act as protective immobilization media for biologically active molecules. This makes it a suitable candidate for biosensor applications. The glasslike nature and good optical quality allows for light addressable entities to be incorporated and accessed using spectroscopy. This type of matrix, once formed, can be anything from an ordered gel to a robust glassy block depending on the aging process. In this work we apply confocal microscopy and time-resolved fluorescence techniques to study both rotational and lateral diffusion with aging time within a silica sol-gel derived monolith. An enzyme, horseradish peroxidase, was labeled with Alexa Fluor 488 and rotation related to both the enzyme and the probe monitored during the matrix aging process. Diffusion coefficients of between ca. 0.5 x 10(-7) and 4 x 10(-7) cm2 s(-1) were obtained from preliminary FRAP measurements of fluorescein and correlated to differences in the catalytic activity of HRP incorporated in the monolith. 相似文献
93.
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95.
Stanley A. Bajue Choy Lewis Karen Clarke Fitzgerald B. Bramwell Brian O. Patrick Carolyn Pratt Brock 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(6):m207-m211
The title complexes [μ‐(E)‐4,4′‐(ethene‐1,2‐diyl)dipyridine‐κ2N:N′]bis[halotris(4‐methylphenyl)tin(IV)], [Sn2(C7H7)6X2(C12H10N2)], where halo is chloro (X = Cl) and bromo (X = Br) are isostructural. In both crystals, the molecules lie on inversion centers, and there are voids of ca 80 Å3 that could, but apparently do not, accommodate water molecules. The corresponding iodo structure (X = I) is almost, but not quite, isostructural with the other two compounds; when Br is changed to I, the length of the c axis decreases by more than 1 Å and the voids are no longer large enough to accomodate any solvent molecule. The related complex [μ‐(E)‐4,4′‐(ethene‐1,2‐diyl)dipyridine‐κ2N:N′]bis[chlorotriphenyltin(IV)], [Sn2(C6H5)6Cl2(C12H10N2)], crystallizes in a related structure, but the molecules lie on general rather than on special positions. The molecular structures of the four complexes are similar, but the conformation of the phenyl derivative is approximately eclipsed rather than staggered. 相似文献
96.
Kamil Godula David Rabuka Ki Tae Nam Carolyn R. Bertozzi Prof. 《Angewandte Chemie (International ed. in English)》2009,48(27):4973-4976
Click to view : Glycopolymers can be used to display glycans on microarrays in native‐like architectures. The structurally uniform alkyne‐terminated mucin mimetic glycopolymers (see picture; TR=fluorophore) were printed on azide‐functionalized chips by microcontact printing in the presence of a copper catalyst. The surface‐bound glycopolymers bind lectins in a ligand‐specific manner.
97.
Pamela V. Chang Xing Chen Chris Smyrniotis Alexander Xenakis Tianshun Hu Carolyn R. Bertozzi Prof. Peng Wu Prof. 《Angewandte Chemie (International ed. in English)》2009,48(22):4030-4033
Sialome sweet sialome : As sialic acids are involved in many host–pathogen recognition events and are markers of embryonic and malignant tissues, there is great interest in methods for the enrichment and identification of sialylated glycoproteins from complex tissues. Now N‐(4‐pentynoyl)mannosamine can be used to metabolically label sialylated glycoproteins in living animals, enabling future identification of new biomarkers.
98.
The boron-atom insertion reaction of nido-9,11-I(2)-7,8-C(2)B(9)H(9)(2-), with the HBCl(2):SMe(2) complex yields closo-4,7-I(2)-1,2-C(2)B(10)H(10), 1, in excellent yield. Although the two boron atoms (B3 and B6) nearest to the carbon atoms in 1 are equally available for attack by nucleophiles, the boron-degradation reaction of 1 with alkoxide ion occurs only at the B6 vertex, yielding regioselectively [(CH(3))(3)NH][nido-2,4-I(2)-7,8-C(2)B(9)H(10)], 2. The molecular structures of 1 and 2 have been determined by X-ray diffraction studies. Crystallographic data are as follows. For 1, monoclinic, space group P2(1)/n, a = 6.9199(19) Angstroms, b = 23.9560(7) Angstroms, c = 7.2870(2) Angstroms, beta = 94.081(4) degrees, V = 1204.9(6) Angstroms(3), Z = 4, rho(calcd) = 2.18 g cm(-3), R = 0.020, R(w) = 0.0610; for 2, orthorhombic, space group Pca2(1), a = 14.1141(7) Angstroms, b = 7.0276(4) Angstroms, c = 16.4602(9) Angstroms, V = 1632.7(15) Angstroms(3), Z = 4, rho(calcd) = 1.81 gcm(-3), R = 0.022, R(w) = 0.0623. 相似文献
99.
Xiong Y Shi L Chen B Mayer MU Lower BH Londer Y Bose S Hochella MF Fredrickson JK Squier TC 《Journal of the American Chemical Society》2006,128(43):13978-13979
The purified outer membrane bacterial protein OmcA binds densely to the surface of hematite (Fe2O3), permitting direct electron transfer to this solid mineral to reduce Fe (III) with an electron flux of about 1013 electrons /cm2/s. In the presence of hematite, there is a substantial increase in the amplitude of internal protein motions that correlate with metal reduction. Binding is highly favorable, with a partition coefficient of approximately 2 x 105 (DeltaGo' = -28 kJ/mol), where approximately 1014 OmcA proteins bind per cm2 to the solid metal surface, indicating the utility of using purified OmcA in the construction of a biofuel cell. 相似文献
100.
Carolyn A. Pugh 《Journal of organometallic chemistry》2006,691(4):680-686
The synthesis of 1,6-diferrocenylhexane-1,6-dione (I), 1-ferrocenylcarbonyl-2-ferrocenylcyclopentene (II) and 1,6-diferrocenylhexane (III) is reported. All three compounds were characterized by 1H NMR, 13C NMR, and infra-red spectroscopy, mass spectrometry, cyclic voltammetry and chronoamperometry. Compounds I and III each exhibit a single two electron transfer, while compound (II) exhibits two single electron transfers. Compounds (I) and (II) were further studied by single crystal X-ray diffraction. In compound (I), both carbonyl groups are in plane with the adjacent ferrocenyl Cp ring. For compound (II) one of the ferrocenyl Cp rings is coplanar with the carbonyl group, the other with the double bond of the cyclopentene ring, but the CO moiety and the double bond are basically perpendicular to each other. 相似文献